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Zada S, Khan M, Sajjad W, Rafiq M, Sajjad W, Su Z. Isolation and characterization of a cold-active, detergent-stable protease from Serratia sp. TGS1. J Basic Microbiol 2023; 63:1165-1176. [PMID: 37469200 DOI: 10.1002/jobm.202300192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Revised: 06/15/2023] [Accepted: 06/28/2023] [Indexed: 07/21/2023]
Abstract
Psychrophiles are cold-adapted microorganisms living in cold regions and are known to generate cold-active enzymes such as proteases, lipases, and peptidases. These types of enzymes are a major part of the market of the food and textile sector. This study aimed to isolate and characterize the cold-active and detergent-stable, extracellular protease from psychotrophic bacteria Serratia sp. TGS1 (OQ654005). Protease was purified by gel permeation chromatography using Sephadex G-75. The specific activity of the purified protease was 250 U/mg at 15°C, with a purification fold of 5.68 and a percentage yield of 60%. The cold active protease was stable within a temperature range of 5-30°C and a pH range of 6-10. Ca+2 and Mg+2 enhanced its activity while chelators like ethylenediaminetetraacetic acid inhibited cold active protease, showing it as metalloprotease in nature. The enzyme was sensitive to Cu+2 , Zn+2 , and Hg+2 , and the proteolytic activity decreased upon treatment with heavy metals. The molecular weight of the protease was estimated to be 47 kDa using sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. Proteins within a specific range of molecular weight possess desirable properties for industrial enzyme use. By working on a specific range, the researchers intended to examine an enzyme to examine its specific characteristics. The purified protease showed high stability to detergents like SDS, Tween 20, Tween 60, and Triton X. The maximum velocity Vmax and Km values were 59.90 mg/min/mL and 1.53 mg/mL, respectively. The obtained protease exhibited an interesting activity at a broad range of pH (6-10) and stability at low temperatures (5-30°C) and detergents. Such enzymatic features of versatile and potent cold-active enzymes enhance their industrial applications to meet food, dairy, and laundry requirements.
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Affiliation(s)
- Sahib Zada
- Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou, China
| | - Mohsin Khan
- Department of Biological Sciences, Ohio University Athens, Athens, Ohio, USA
| | - Wasim Sajjad
- State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, China
| | - Muhammad Rafiq
- Department of Microbiology, Faculty of Life Sciences and Informatics, Engineering and Management Sciences, Balochistan University of IT, Quetta, Pakistan
| | - Wasim Sajjad
- Department of Biological Sciences, National University of Medical Sciences, Rawalpindi, Pakistan
| | - Zheng Su
- Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou, China
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2
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Dacres H, Weihs F, Wang J, Anderson A, Trowell SC. Bioluminescence resonance energy transfer biosensor for measuring activity of a protease secreted by Pseudomonas fluorescens growing in milk. Anal Chim Acta 2023; 1270:341401. [PMID: 37311608 DOI: 10.1016/j.aca.2023.341401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 05/18/2023] [Accepted: 05/20/2023] [Indexed: 06/15/2023]
Abstract
Bacterial proteases are sporadic contributors to milk spoilage, reducing the quality of ultra-heat treated (UHT) milk and other dairy products. Current methods for measuring bacterial protease activity in milk are insensitive and too slow to be used in routine testing in dairy processing plants. We have designed a novel bioluminescence resonance energy transfer (BRET)-based biosensor to measure the activity of proteases secreted by bacteria in milk. The BRET-based biosensor is highly selective for bacterial protease activity compared with other proteases tested, notably including plasmin, which is abundant in milk. It incorporates a novel peptide linker that is selectively cleaved by P. fluorescens AprX proteases. The peptide linker is flanked by green fluorescent protein (GFP2) at the N-terminus and a variant Renilla luciferase (RLuc2) at the C-terminus. Complete cleavage of the linker by bacterial proteases from Pseudomonas fluorescens strain 65, leads to a 95% decrease in the BRET ratio. We applied an azocasein-based calibration method to the AprX biosensor using standard international enzyme activity units. In a 10-min assay, the detection limit for AprX protease activity in buffer was equivalent to 40 pg/mL (≈0.8 pM, 22 μU/mL) and 100 pg/mL (≈2pM, 54 μU/mL) in 50% (v/v) full fat milk. The EC50 values were 1.1 ± 0.3 ng/mL (87 μU/mL) and 6.8 ± 0.2 ng/mL (540 μU/mL), respectively. The biosensor was approximately 800x more sensitive than the established FITC-Casein method in a 2-h assay, the shortest feasible time for the latter method. The protease biosensor is sensitive and fast enough to be used in production settings. It is suitable for measuring bacterial protease activity in raw and processed milk, to inform efforts to mitigate the effects of heat-stable bacterial proteases and maximise the shelf-life of dairy products.
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Affiliation(s)
- H Dacres
- CSIRO Health & Biosecurity, Food Innovation Centre, 671 Sneydes Road, Werribee, VIC, 3030, Australia
| | - F Weihs
- PPB Technology Pty Ltd, PO Box 265, Erindale Centre, ACT, 2903, Australia; CSIRO Health & Biosecurity, Canberra, ACT, 2601, Australia.
| | - J Wang
- CSIRO Health & Biosecurity, Canberra, ACT, 2601, Australia
| | - A Anderson
- CSIRO Health & Biosecurity, Canberra, ACT, 2601, Australia
| | - S C Trowell
- PPB Technology Pty Ltd, PO Box 265, Erindale Centre, ACT, 2903, Australia; CSIRO Health & Biosecurity, Canberra, ACT, 2601, Australia
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3
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Synergistic inhibition of Pseudomonas fluorescens growth and proteases activities via sodium chlorite-based oxyhalogen. World J Microbiol Biotechnol 2023; 39:33. [PMID: 36469174 PMCID: PMC9722865 DOI: 10.1007/s11274-022-03471-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Accepted: 11/15/2022] [Indexed: 12/07/2022]
Abstract
Pseudomonas fluorescens is considered among the main spoilage microorganisms due to its ability to produce proteases. Food deterioration caused by spoilage microorganisms has a major impact on food quality and the environment. The inactivation of Pseudomonas fluorescens growth and protease production was intensively investigated with the use of Salmide®, A Sodium Chlorite-Based Oxy-halogen Disinfectant. A unique M9 media was also developed to assure sufficient protease productions with different mutants of Pseudomonas fluorescens as a microbioreactor. Mutations were induced by classical whole-cell mutagenesis using N-methyl-N'- nitro-N-nitrosoguanidine (NTG). A dramatic decrease occurred in protease activity when different Salmide concentrations (5, 10, and 15 ppm) were added to the growth culture followed by a complete inhibition concentration (20, 25, 50, and 100 ppm) of Salmide. However, no significant inhibition occurred once it is secreted out of cells. Some mutants were resistant and remains highly stable with high protease production under stressful conditions of Sodium Chlorite-Based Oxy-halogen. The production of the protease showed a linear correlation with the increase in incubation time using a continuous culture bioreactor system and recorded maximum protease activity after 40 h. Our findings would offer alternative antimicrobial procedures for food and industrial sectors.
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Quintieri L, Caputo L, Brasca M, Fanelli F. Recent Advances in the Mechanisms and Regulation of QS in Dairy Spoilage by Pseudomonas spp. Foods 2021; 10:foods10123088. [PMID: 34945641 PMCID: PMC8701193 DOI: 10.3390/foods10123088] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 11/28/2021] [Accepted: 12/08/2021] [Indexed: 11/16/2022] Open
Abstract
Food spoilage is a serious issue dramatically impacting the worldwide need to counteract food insecurity. Despite the very expensive application of low temperatures, the proper conservation of fresh dairy products is continuously threatened at different stages of production and commercialization by psychrotrophic populations mainly belonging to the Pseudomonas genus. These bacteria cause discolouration, loss of structure, and off-flavours, with fatal implications on the quality and shelf-life of products. While the effects of pseudomonad decay have been widely reported, the mechanisms responsible for the activation and regulation of spoilage pathways are still poorly explored. Recently, molecule signals and regulators involved in quorum sensing (QS), such as homoserine lactones, the luxR/luxI system, hdtS, and psoR, have been detected in spoiled products and bacterial spoiler species; this evidence suggests the role of bacterial cross talk in dairy spoilage and paves the way towards the search for novel preservation strategies based on QS inhibition. The aim of this review was to investigate the advancements achieved by the application of omic approaches in deciphering the molecular mechanisms controlled by QS systems in pseudomonads, by focusing on the regulators and metabolic pathways responsible for spoilage of fresh dairy products. In addition, due the ability of pseudomonads to quickly spread in the environment as biofilm communities, which may also include pathogenic and multidrug-resistant (MDR) species, the risk derived from the gaps in clearly defined and regulated sanitization actions is underlined.
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Affiliation(s)
- Laura Quintieri
- Institute of Sciences of Food Production, National Research Council of Italy, 70126 Bari, Italy; (L.C.); (F.F.)
- Correspondence: author:
| | - Leonardo Caputo
- Institute of Sciences of Food Production, National Research Council of Italy, 70126 Bari, Italy; (L.C.); (F.F.)
| | - Milena Brasca
- Institute of Sciences of Food Production, National Research Council of Italy, 20133 Milan, Italy;
| | - Francesca Fanelli
- Institute of Sciences of Food Production, National Research Council of Italy, 70126 Bari, Italy; (L.C.); (F.F.)
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5
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Behzadi P, Baráth Z, Gajdács M. It's Not Easy Being Green: A Narrative Review on the Microbiology, Virulence and Therapeutic Prospects of Multidrug-Resistant Pseudomonas aeruginosa. Antibiotics (Basel) 2021; 10:42. [PMID: 33406652 PMCID: PMC7823828 DOI: 10.3390/antibiotics10010042] [Citation(s) in RCA: 109] [Impact Index Per Article: 36.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 12/29/2020] [Accepted: 12/31/2020] [Indexed: 12/11/2022] Open
Abstract
Pseudomonas aeruginosa is the most frequent cause of infection among non-fermenting Gram-negative bacteria, predominantly affecting immunocompromised patients, but its pathogenic role should not be disregarded in immunocompetent patients. These pathogens present a concerning therapeutic challenge to clinicians, both in community and in hospital settings, due to their increasing prevalence of resistance, and this may lead to prolonged therapy, sequelae, and excess mortality in the affected patient population. The resistance mechanisms of P. aeruginosa may be classified into intrinsic and acquired resistance mechanisms. These mechanisms lead to occurrence of resistant strains against important antibiotics-relevant in the treatment of P. aeruginosa infections-such as β-lactams, quinolones, aminoglycosides, and colistin. The occurrence of a specific resistotype of P. aeruginosa, namely the emergence of carbapenem-resistant but cephalosporin-susceptible (Car-R/Ceph-S) strains, has received substantial attention from clinical microbiologists and infection control specialists; nevertheless, the available literature on this topic is still scarce. The aim of this present review paper is to provide a concise summary on the adaptability, virulence, and antibiotic resistance of P. aeruginosa to a readership of basic scientists and clinicians.
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Affiliation(s)
- Payam Behzadi
- Department of Microbiology, College of Basic Sciences, Shahr-e-Qods Branch, Islamic Azad University, Tehran 37541-374, Iran;
| | - Zoltán Baráth
- Department of Prosthodontics, Faculty of Dentistry, University of Szeged, Tisza Lajos körút 62-64, 6720 Szeged, Hungary;
| | - Márió Gajdács
- Institute of Medical Microbiology, Faculty of Medicine, Semmelweis University, 1089 Budapest, Hungary
- Department of Pharmacodynamics and Biopharmacy, Faculty of Pharmacy, University of Szeged, 6720 Szeged, Hungary
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Maier C, Huptas C, von Neubeck M, Scherer S, Wenning M, Lücking G. Genetic Organization of the aprX-lipA2 Operon Affects the Proteolytic Potential of Pseudomonas Species in Milk. Front Microbiol 2020; 11:1190. [PMID: 32587583 PMCID: PMC7298200 DOI: 10.3389/fmicb.2020.01190] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Accepted: 05/11/2020] [Indexed: 11/30/2022] Open
Abstract
Psychrotolerant Pseudomonas species are a main cause of proteolytic spoilage of ultra-high temperature (UHT) milk products due to the secretion of the heat-resistant metallopeptidase AprX, which is encoded by the first gene of the aprX-lipA2 operon. While the proteolytic property has been characterized for many different Pseudomonas isolates, the underlying aprX-lipA2 gene organization was only described for a few strains so far. In this study, the phylogenomic analysis of 185 Pseudomonas type strains revealed that the presence of aprX is strongly associated to a monophylum composed of 81 species, of which 83% carried the aprX locus. Furthermore, almost all type strains of known milk-relevant species were shown to be members of the three monophyletic groups P. fluorescens, P. gessardii, and P. fragi. In total, 22 different types of aprX-lipA2 genetic organizations were identified in the genus, whereby 31% of the species tested carried the type 1 operon structure consisting of eight genes (aprXIDEF prtAB lipA2). Other genetic structures differed from type 1 mainly in the presence and location of genes coding for two lipases (lipA1 and lipA2) and putative autotransporters (prtA and prtB). The peptidase activity of 129 strains, as determined on skim milk agar and in UHT-milk, correlated largely with different aprX-lipA2 gene compositions. Particularly, isolates harboring the type 1 operon were highly proteolytic, while strains with other operon types, especially ones lacking prtA and prtB, exhibited significantly lower peptidase activities. In conclusion, the phylogenomic position and the aprX-lipA2 gene organization specify the proteolytic potential of Pseudomonas isolates. In addition, however, an interplay of several environmental factors and intrinsic traits influences production and activity of AprX, leading to strain-specific proteolytic phenotypes.
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Affiliation(s)
- Christopher Maier
- ZIEL Institute for Food and Health, Wissenschaftszentrum Weihenstephan, Technische Universität München, Freising, Germany
| | - Christopher Huptas
- Lehrstuhl für Mikrobielle Ökologie, Wissenschaftszentrum Weihenstephan, Technische Universität München, Freising, Germany
| | - Mario von Neubeck
- ZIEL Institute for Food and Health, Wissenschaftszentrum Weihenstephan, Technische Universität München, Freising, Germany
| | - Siegfried Scherer
- ZIEL Institute for Food and Health, Wissenschaftszentrum Weihenstephan, Technische Universität München, Freising, Germany
- Lehrstuhl für Mikrobielle Ökologie, Wissenschaftszentrum Weihenstephan, Technische Universität München, Freising, Germany
| | - Mareike Wenning
- Bavarian Health and Food Safety Authority (LGL), Oberschleißheim, Germany
| | - Genia Lücking
- ZIEL Institute for Food and Health, Wissenschaftszentrum Weihenstephan, Technische Universität München, Freising, Germany
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7
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Paludetti LF, Kelly AL, Gleeson D. Effect of thermoresistant protease of Pseudomonas fluorescens on rennet coagulation properties and proteolysis of milk. J Dairy Sci 2020; 103:4043-4055. [PMID: 32147268 DOI: 10.3168/jds.2019-17771] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Accepted: 12/26/2019] [Indexed: 01/05/2023]
Abstract
This study aimed to investigate the effect of different activity levels of a thermoresistant protease, produced by Pseudomonas fluorescens (ATCC 17556), on the cheesemaking properties of milk and proteolysis levels. Sterilized reconstituted skim milk powder was inoculated with the bacteria, and after incubation, centrifuged to obtain a supernatant-containing protease. Raw milk was collected and inoculated to obtain a protease activity of 0.15, 0.60, and 1.5 U/L of milk (treatments P1, P4, and P10, respectively). One sample was not inoculated (control) and noninoculated supernatant was added to a fifth sample to be used as a negative control. Samples were stored at 4°C for 72 h. After 0, 48, and 72 h, the rennet coagulation properties and proteolysis levels were assessed. The protease produced was thermoresistant, as no significant differences were observed in the activity in the pasteurized (72°C for 15 s) and nonpasteurized supernatants. The chromatograms and electrophoretograms indicated that the protease preferably hydrolyzed κ-casein and β-casein, and levels of proteolysis increased with added protease activity over storage time. The hydrolysis of αS-caseins and major whey proteins increased considerably in P10 milk samples. At 0 h, the increase in the level of protease activity decreased the rennet coagulation time (RCT, min) of the samples, possibly due to synergistic proteolysis of κ-casein into para-κ-casein. However, over prolonged storage, hydrolysis of β-casein and αS-casein increased in P4 and P10 samples. The RCT of P4 samples increased over time and the coagulum became softer, whereas P10 samples did not coagulate after 48 h of storage. In contrast, the RCT of P1 samples decreased over time and a firmer coagulum was obtained, possibly due to a lower rate of hydrolysis of β-casein and αS-casein. Increased levels of protease could result in further hydrolysis of caseins, affecting the processability of milk over storage time.
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Affiliation(s)
- Lizandra F Paludetti
- Teagasc, Animal and Grassland Research and Innovation Centre, Moorepark, Fermoy, County Cork P61 C996, Ireland; School of Food and Nutritional Sciences, University College Cork, County Cork T12 K8AF, Ireland
| | - Alan L Kelly
- School of Food and Nutritional Sciences, University College Cork, County Cork T12 K8AF, Ireland
| | - David Gleeson
- Teagasc, Animal and Grassland Research and Innovation Centre, Moorepark, Fermoy, County Cork P61 C996, Ireland.
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8
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Quintieri L, Fanelli F, Caputo L. Antibiotic Resistant Pseudomonas Spp. Spoilers in Fresh Dairy Products: An Underestimated Risk and the Control Strategies. Foods 2019; 8:E372. [PMID: 31480507 PMCID: PMC6769999 DOI: 10.3390/foods8090372] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 08/22/2019] [Accepted: 08/23/2019] [Indexed: 01/14/2023] Open
Abstract
Microbial multidrug resistance (MDR) is a growing threat to public health mostly because it makes the fight against microorganisms that cause lethal infections ever less effective. Thus, the surveillance on MDR microorganisms has recently been strengthened, taking into account the control of antibiotic abuse as well as the mechanisms underlying the transfer of antibiotic genes (ARGs) among microbiota naturally occurring in the environment. Indeed, ARGs are not only confined to pathogenic bacteria, whose diffusion in the clinical field has aroused serious concerns, but are widespread in saprophytic bacterial communities such as those dominating the food industry. In particular, fresh dairy products can be considered a reservoir of Pseudomonas spp. resistome, potentially transmittable to consumers. Milk and fresh dairy cheeses products represent one of a few "hubs" where commensal or opportunistic pseudomonads frequently cohabit together with food microbiota and hazard pathogens even across their manufacturing processes. Pseudomonas spp., widely studied for food spoilage effects, are instead underestimated for their possible impact on human health. Recent evidences have highlighted that non-pathogenic pseudomonads strains (P. fluorescens, P. putida) are associated with some human diseases, but are still poorly considered in comparison to the pathogen P. aeruginosa. In addition, the presence of ARGs, that can be acquired and transmitted by horizontal genetic transfer, further increases their risk and the need to be deeper investigated. Therefore, this review, starting from the general aspects related to the physiological traits of these spoilage microorganisms from fresh dairy products, aims to shed light on the resistome of cheese-related pseudomonads and their genomic background, current methods and advances in the prediction tools for MDR detection based on genomic sequences, possible implications for human health, and the affordable strategies to counteract MDR spread.
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Affiliation(s)
- Laura Quintieri
- Institute of Sciences of Food Production, National Research Council of Italy, Via G. Amendola 122/O, 70126 Bari, Italy
| | - Francesca Fanelli
- Institute of Sciences of Food Production, National Research Council of Italy, Via G. Amendola 122/O, 70126 Bari, Italy.
| | - Leonardo Caputo
- Institute of Sciences of Food Production, National Research Council of Italy, Via G. Amendola 122/O, 70126 Bari, Italy
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9
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Pseudomonas fluorescens: a potential food spoiler and challenges and advances in its detection. ANN MICROBIOL 2019. [DOI: 10.1007/s13213-019-01501-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
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10
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Zhang C, Bijl E, Svensson B, Hettinga K. The Extracellular Protease AprX fromPseudomonasand its Spoilage Potential for UHT Milk: A Review. Compr Rev Food Sci Food Saf 2019; 18:834-852. [DOI: 10.1111/1541-4337.12452] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 03/06/2019] [Accepted: 03/10/2019] [Indexed: 01/10/2023]
Affiliation(s)
- Chunyue Zhang
- Dairy Science and Technology, Food Quality and Design GroupWageningen Univ. and Research P.O. Box 17 6700 AA Wageningen the Netherlands
| | - Etske Bijl
- Dairy Science and Technology, Food Quality and Design GroupWageningen Univ. and Research P.O. Box 17 6700 AA Wageningen the Netherlands
| | - Birgitta Svensson
- Tetra Pak Processing Systems ABRuben Rausings gata 221 86 Lund Sweden
| | - Kasper Hettinga
- Dairy Science and Technology, Food Quality and Design GroupWageningen Univ. and Research P.O. Box 17 6700 AA Wageningen the Netherlands
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11
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Purification and Characterization of Microbial Protease Produced Extracellularly from Bacillus subtilis FBL-1. BIOTECHNOL BIOPROC E 2018. [DOI: 10.1007/s12257-017-0495-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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12
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Boulkour Touioui S, Zaraî Jaouadi N, Bouacem K, Ben Ayed R, Rekik H, Zenati B, Kourdali S, Boudjella H, Sabaou N, Bejar S, El Hattab M, Badis A, Annane R, Jaouadi B. Biochemical and molecular characterization of a novel metalloprotease from Pseudomonas fluorescens strain TBS09. Int J Biol Macromol 2018; 107:2351-2363. [DOI: 10.1016/j.ijbiomac.2017.10.116] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Revised: 10/14/2017] [Accepted: 10/17/2017] [Indexed: 10/18/2022]
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13
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Machado SG, Baglinière F, Marchand S, Van Coillie E, Vanetti MCD, De Block J, Heyndrickx M. The Biodiversity of the Microbiota Producing Heat-Resistant Enzymes Responsible for Spoilage in Processed Bovine Milk and Dairy Products. Front Microbiol 2017; 8:302. [PMID: 28298906 PMCID: PMC5331058 DOI: 10.3389/fmicb.2017.00302] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 02/14/2017] [Indexed: 12/28/2022] Open
Abstract
Raw bovine milk is highly nutritious as well as pH-neutral, providing the ideal conditions for microbial growth. The microbiota of raw milk is diverse and originates from several sources of contamination including the external udder surface, milking equipment, air, water, feed, grass, feces, and soil. Many bacterial and fungal species can be found in raw milk. The autochthonous microbiota of raw milk immediately after milking generally comprises lactic acid bacteria such as Lactococcus, Lactobacillus, Streptococcus, and Leuconostoc species, which are technologically important for the dairy industry, although they do occasionally cause spoilage of dairy products. Differences in milking practices and storage conditions on each continent, country and region result in variable microbial population structures in raw milk. Raw milk is usually stored at cold temperatures, e.g., about 4°C before processing to reduce the growth of most bacteria. However, psychrotrophic bacteria can proliferate and contribute to spoilage of ultra-high temperature (UHT) treated and sterilized milk and other dairy products with a long shelf life due to their ability to produce extracellular heat resistant enzymes such as peptidases and lipases. Worldwide, species of Pseudomonas, with the ability to produce these spoilage enzymes, are the most common contaminants isolated from cold raw milk although other genera such as Serratia are also reported as important milk spoilers, while for others more research is needed on the heat resistance of the spoilage enzymes produced. The residual activity of extracellular enzymes after high heat treatment may lead to technological problems (off flavors, physico-chemical instability) during the shelf life of milk and dairy products. This review covers the contamination patterns of cold raw milk in several parts of the world, the growth potential of psychrotrophic bacteria, their ability to produce extracellular heat-resistant enzymes and the consequences for dairy products with a long shelf life. This problem is of increasing importance because of the large worldwide trade in fluid milk and milk powder.
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Affiliation(s)
- Solimar G Machado
- Instituto Federal do Norte de Minas Gerais - Campus Salinas Salinas, Brazil
| | | | - Sophie Marchand
- Technology and Food Science Unit, Flanders Research Institute for Agriculture, Fischeries and Food (ILVO) Melle, Belgium
| | - Els Van Coillie
- Technology and Food Science Unit, Flanders Research Institute for Agriculture, Fischeries and Food (ILVO) Melle, Belgium
| | - Maria C D Vanetti
- Department of Microbiology, Universidade Federal de Viçosa Viçosa, Brazil
| | - Jan De Block
- Technology and Food Science Unit, Flanders Research Institute for Agriculture, Fischeries and Food (ILVO) Melle, Belgium
| | - Marc Heyndrickx
- Technology and Food Science Unit, Flanders Research Institute for Agriculture, Fischeries and Food (ILVO)Melle, Belgium; Department of Pathology, Bacteriology and Poultry Diseases, Ghent UniversityMerelbeke, Belgium
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14
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Baglinière F, Salgado RL, Salgado CA, Vanetti MCD. Biochemical Characterization of an Extracellular Heat-Stable Protease fromSerratia liquefaciensIsolated from Raw Milk. J Food Sci 2017; 82:952-959. [DOI: 10.1111/1750-3841.13660] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Revised: 01/04/2017] [Accepted: 01/23/2017] [Indexed: 11/27/2022]
Affiliation(s)
- François Baglinière
- Dept. of Microbiology; Federal Univ. of Viçosa; Viçosa MG 36.570-900 Brazil
- CAPES Foundation; Ministry of Education of Brazil; Brasília DF 70.040-020 Brazil
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15
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Andreani NA, Carraro L, Fasolato L, Balzan S, Lucchini R, Novelli E, Cardazzo B. Characterisation of the Thermostable Protease AprX in Strains of Pseudomonas Fluorescens and Impact on the Shelf-life of Dairy Products: Preliminary Results. Ital J Food Saf 2016; 5:6175. [PMID: 28217561 PMCID: PMC5225826 DOI: 10.4081/ijfs.2016.6175] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Revised: 11/16/2016] [Accepted: 11/19/2016] [Indexed: 01/13/2023] Open
Abstract
Bacterial proteases are involved in food spoilage and shelf-life reduction. Among the bacterial proteases, a predominant role in spoilage of dairy products seems to be played by the thermostable metallo-protease AprX, which is produced by various strains of Pseudomonas fluorescens. Differences in AprX enzyme activity among different strains were highlighted, but the most proteolytic strains were not identified. In this study, the presence of the aprX gene was evaluated in 69 strains isolated from food matrices and 18 reference strains belonging to the P. fluorescens group, which had been previously typed by the multi locus sequence typing method. Subsequently, a subset of reference strains was inoculated in ultra-high temperature milk, and the expression of the aprX gene was evaluated at 22 and 6°C. On the same milk samples, the proteolytic activity was then evaluated through Azocasein and trinitrobenzenesulfonic acid solution assays. Finally, to assess the applicability of the former assay directly on dairy products the proteolityc activity was tested on industrial ricotta samples using the Azocasein assay. These results demonstrate the spread of aprX gene in most strains tested and the applicability of Azocasein assay to monitor the proteolytic activity in dairy products.
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Affiliation(s)
- Nadia Andrea Andreani
- Department of Comparative Biomedicine and Food Science, University of Padua , Legnaro (PD), Italy
| | - Lisa Carraro
- Department of Comparative Biomedicine and Food Science, University of Padua , Legnaro (PD), Italy
| | - Luca Fasolato
- Department of Comparative Biomedicine and Food Science, University of Padua , Legnaro (PD), Italy
| | - Stefania Balzan
- Department of Comparative Biomedicine and Food Science, University of Padua , Legnaro (PD), Italy
| | - Rosaria Lucchini
- Institute for Experimental Veterinary Medicine of Venezie , Legnaro (PD), Italy
| | - Enrico Novelli
- Department of Comparative Biomedicine and Food Science, University of Padua , Legnaro (PD), Italy
| | - Barbara Cardazzo
- Department of Comparative Biomedicine and Food Science, University of Padua , Legnaro (PD), Italy
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16
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Alves MP, Salgado RL, Eller MR, Vidigal PMP, Fernandes de Carvalho A. Characterization of a heat-resistant extracellular protease from Pseudomonas fluorescens 07A shows that low temperature treatments are more effective in deactivating its proteolytic activity. J Dairy Sci 2016; 99:7842-7851. [PMID: 27497896 DOI: 10.3168/jds.2016-11236] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Accepted: 05/11/2016] [Indexed: 01/25/2023]
Abstract
This work discusses the biological and biochemical characterization of an extracellular protease produced by Pseudomonas fluorescens. The enzyme has a molecular weight of 49.486 kDa and hydrolyzes gelatin, casein, and azocasein, but not BSA. Its maximum activity is found at 37°C and pH 7.5, but it retained almost 70% activity at pH 10.0. It was shown to be a metalloprotease inhibited by Cu(2+), Ni(2+), Zn(2+), Hg(2+), Fe(2+), and Mg(2+), but induced by Mn(2+). After incubation at 100°C for 5min, the enzyme presented over 40% activity, but only 14 to 30% when submitted to milder heat treatments. This behavior may cause significant problems under conditions commonly used for the processing and storage of milk and dairy products, particularly UHT milk. A specific peptide sequenced by mass spectrometer analysis allowed the identification of gene that encodes this extracellular protease in the genome of Pseudomonas fluorescens 07A strain. The enzyme has 477 AA and highly conserved Ca(2+)- and Zn(2+)-binding domains, indicating that Ca(2+), the main ion in milk, is also a cofactor. This work contributes to the understanding of the biochemical aspects of enzyme activity and associates them with its sequence and structure. These findings are essential for the full understanding and control of these enzymes and the technological problems they cause in the dairy industry.
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Affiliation(s)
- Maura P Alves
- Inovaleite Laboratory, Department of Food Technology, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil, 36570000
| | - Rafael L Salgado
- Department of Biochemistry and Molecular Biology, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil, 36570000
| | - Monique R Eller
- Department of Food Technology, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil, 36570000
| | - Pedro Marcus P Vidigal
- Núcleo de Análise de Biomoléculas (NuBioMol), Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil, 36570000
| | - Antonio Fernandes de Carvalho
- Inovaleite Laboratory, Department of Food Technology, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil, 36570000.
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17
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Stuknytė M, Decimo M, Colzani M, Silvetti T, Brasca M, Cattaneo S, Aldini G, De Noni I. Extracellular thermostable proteolytic activity of the milk spoilage bacterium Pseudomonas fluorescens PS19 on bovine caseins. J Dairy Sci 2016; 99:4188-4195. [DOI: 10.3168/jds.2016-10894] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Accepted: 02/09/2016] [Indexed: 11/19/2022]
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18
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Identification and characterization of a heat-resistant protease from Serratia liquefaciens isolated from Brazilian cold raw milk. Int J Food Microbiol 2016; 222:65-71. [PMID: 26874224 DOI: 10.1016/j.ijfoodmicro.2016.01.014] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Revised: 01/12/2016] [Accepted: 01/23/2016] [Indexed: 11/24/2022]
Abstract
The cold storage of raw milk before heat treatment in dairy industry promotes the growth of psychrotrophic microorganisms, which are known for their ability to produce heat-resistant proteolytic enzymes. Although Pseudomonas is described as the main causative genus for high proteolytic spoilage potential in dairy products, Serratia liquefaciens secretes proteases and may be found in raw milk samples as well. However, at the present there is no information about the proteolytic spoilage potential of S. liquefaciens in milk after heat-treatment. The main aim of this research was to assess the proteolytic spoilage potential of S. liquefaciens isolated from Brazilian raw milk and to characterize the involved protease. S. liquefaciens was shown to secrete one heat-resistant spoilage metalloprotease of, approximately, 52 kDa encoded by the ser2 gene. The heat-resistance of Ser2 was similar to the aprX encoded metalloprotease produced by Pseudomonas. Although the ser2 gene was detected in all S. liquefaciens isolates tested in this study, the proteolytic activity of the isolates in milk was highly heterogeneous. Since nucleotide and deduced amino acid sequences of ser2 of all tested isolates are identical, this heterogeneity may be attributed to differences in enzyme expression levels or post-translational modifications.
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19
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Baur C, Krewinkel M, Kutzli I, Kranz B, von Neubeck M, Huptas C, Wenning M, Scherer S, Stoeckel M, Hinrichs J, Stressler T, Fischer L. Isolation and characterisation of a heat-resistant peptidase from Pseudomonas panacis withstanding general UHT processes. Int Dairy J 2015. [DOI: 10.1016/j.idairyj.2015.04.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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20
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Matéos A, Guyard-Nicodème M, Baglinière F, Jardin J, Gaucheron F, Dary A, Humbert G, Gaillard JL. Proteolysis of milk proteins by AprX, an extracellular protease identified in Pseudomonas LBSA1 isolated from bulk raw milk, and implications for the stability of UHT milk. Int Dairy J 2015. [DOI: 10.1016/j.idairyj.2015.04.008] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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21
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Chen CM, Liu JJ, Chou CW, Lai CH, Wu LT. RpA, an extracellular protease similar to the metalloprotease of serralysin family, is required for pathogenicity of Ralstonia pickettii. J Appl Microbiol 2015; 119:1101-11. [DOI: 10.1111/jam.12903] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Revised: 07/05/2015] [Accepted: 07/07/2015] [Indexed: 11/25/2022]
Affiliation(s)
- C.-M. Chen
- Division of Infectious Disease; Department of Internal Medicine; Tungs' Taichung MetroHarbor Hospital; Taichung Taiwan
| | - J.-J. Liu
- The Institute of Medical Science and Department of Microbiology; China Medical University; Taichung Taiwan
| | - C.-W. Chou
- Department of Cosmeceutics; College of Pharmacy; China Medical University; Taichung Taiwan
| | - C.-H. Lai
- The Institute of Medical Science and Department of Microbiology; China Medical University; Taichung Taiwan
| | - L.-T. Wu
- The Institute of Medical Science and Department of Microbiology; China Medical University; Taichung Taiwan
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22
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Banerjee G, Mukherjee S, Bhattacharya S, Ray AK. Purification and Characterization of Extracellular Protease and Amylase Produced by the Bacterial Strain, Corynebacterium alkanolyticum ATH3 Isolated from Fish Gut. ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING 2015. [DOI: 10.1007/s13369-015-1809-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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23
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Draft Genome Sequence of Pseudomonas fluorescens SRM1, an Isolate from Spoiled Raw Milk. GENOME ANNOUNCEMENTS 2015; 3:3/2/e00138-15. [PMID: 25792057 PMCID: PMC4395049 DOI: 10.1128/genomea.00138-15] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Pseudomonas fluorescens is considered a major milk spoilage organism due to its psychrotrophic nature and ability to produce heat-stable proteases and lipases. Here, we report the draft genome and annotation of P. fluorescens SRM1 isolated from spoiled raw milk and the presence of an operon encoding spoilage enzymes.
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24
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Ertan H, Cassel C, Verma A, Poljak A, Charlton T, Aldrich-Wright J, Omar SM, Siddiqui KS, Cavicchioli R. A new broad specificity alkaline metalloprotease from a Pseudomonas sp. isolated from refrigerated milk: Role of calcium in improving enzyme productivity. ACTA ACUST UNITED AC 2015. [DOI: 10.1016/j.molcatb.2014.12.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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25
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Martins ML, Pinto UM, Riedel K, Vanetti MC. Milk-deteriorating exoenzymes from Pseudomonas fluorescens 041 isolated from refrigerated raw milk. Braz J Microbiol 2015; 46:207-17. [PMID: 26221110 PMCID: PMC4512081 DOI: 10.1590/s1517-838246120130859] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Accepted: 06/06/2014] [Indexed: 02/01/2023] Open
Abstract
The practice of refrigerating raw milk at the farm has provided a selective advantage for psychrotrophic bacteria that produce heat-stable proteases and lipases causing severe quality problems to the dairy industry. In this work, a protease (AprX) and a lipase (LipM) produced by Pseudomonas fluorescens 041, a highly proteolytic and lipolytic strain isolated from raw milk obtained from a Brazilian farm, have been purified and characterized. Both enzymes were purified as recombinant proteins from Escherichia coli . The AprX metalloprotease exhibited activity in a broad temperature range, including refrigeration, with a maximum activity at 37 °C. It was active in a pH range of 4.0 to 9.0. This protease had maximum activity with the substrates casein and gelatin in the presence of Ca (+2) . The LipM lipase had a maximum activity at 25 °C and a broad pH optimum ranging from 7.0 to 10. It exhibited the highest activity, in the presence of Ca (+2) , on substrates with long-chain fatty acid residues. These results confirm the spoilage potential of strain 041 in milk due to, at least in part, these two enzymes. The work highlights the importance of studies of this kind with strains isolated in Brazil, which has a recent history on the implementation of the cold chain at the dairy farm.
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Affiliation(s)
- Maurilio L. Martins
- Departamento de Ciência e Tecnologia de Alimentos, Instituto Federal do Sudeste de Minas Gerais, Rio Pomba, MG, Brazil
| | - Uelinton M. Pinto
- Departamento de Ciência de Alimentos, Universidade Federal de Ouro Preto, Ouro Preto, MG, Brazil
| | - Katharina Riedel
- Institute of Microbiology, Ernst-Moritz-Arndt University of Greifswald, Germany
| | - Maria C.D. Vanetti
- Departamento de Microbiologia, Universidade Federal deViçosa, Viçosa, MG, Brazil
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26
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Decimo M, Morandi S, Silvetti T, Brasca M. Characterization of Gram-Negative Psychrotrophic Bacteria isolated from Italian Bulk Tank Milk. J Food Sci 2014; 79:M2081-90. [DOI: 10.1111/1750-3841.12645] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2014] [Accepted: 07/24/2014] [Indexed: 11/30/2022]
Affiliation(s)
- Marilù Decimo
- Inst. of Sciences of Food Production; Italian Natl. Research Council; Via Celoria 2 20133 Milan Italy
| | - Stefano Morandi
- Inst. of Sciences of Food Production; Italian Natl. Research Council; Via Celoria 2 20133 Milan Italy
| | - Tiziana Silvetti
- Inst. of Sciences of Food Production; Italian Natl. Research Council; Via Celoria 2 20133 Milan Italy
| | - Milena Brasca
- Inst. of Sciences of Food Production; Italian Natl. Research Council; Via Celoria 2 20133 Milan Italy
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27
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Zhang S, Lv J. Purification and properties of heat-stable extracellular protease from Pseudomonads fluorescens BJ-10. JOURNAL OF FOOD SCIENCE AND TECHNOLOGY 2014; 51:1185-90. [PMID: 24876654 PMCID: PMC4033737 DOI: 10.1007/s13197-012-0620-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Revised: 11/06/2011] [Accepted: 01/13/2012] [Indexed: 10/14/2022]
Abstract
Pseudomonas fluorescens BJ-10, a kind of psychrotrophic bacteria, was isolated from raw milk. It produced an extracellular protease of 47 kDa by SDS-PAGE. The crude proteases were purified by ammonium sulfate fractionation, ion-exchange and gel filtration chromatography. The specific activity of purified protease increased 61.38-fold. The optimum pH and temperature were pH 7.0 and 30 °C, respectively. The purified protease was partially inhibited by DL-dithiothreitol, and the activity increased a little upon Fe(2+) addition. The protease showed typical heat-stable behavior. After treatment at 100 °C for 3 min, more than 94% activity remained. This work might lay the foundation for possible relationship between the heat stable protease and gelation of UHT milk.
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Affiliation(s)
- Shuwen Zhang
- />Key Laboratory of Agro-Food Processing and Quality Control, Ministry of Agriculture, Chinese Academy of Agricultural Sciences, Beijing, 100193 People’s Republic of China
- />Institute of Agro-food Science and Technology, Chinese Academy of Agricultural Sciences(CAAS), Beijing, 100193 People’s Republic of China
| | - Jiaping Lv
- />Key Laboratory of Agro-Food Processing and Quality Control, Ministry of Agriculture, Chinese Academy of Agricultural Sciences, Beijing, 100193 People’s Republic of China
- />Institute of Agro-food Science and Technology, Chinese Academy of Agricultural Sciences(CAAS), Beijing, 100193 People’s Republic of China
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28
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Proteolysis of ultra high temperature-treated casein micelles by AprX enzyme from Pseudomonas fluorescens F induces their destabilisation. Int Dairy J 2013. [DOI: 10.1016/j.idairyj.2013.02.011] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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29
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Bach E, Sant’Anna V, Daroit DJ, Corrêa APF, Segalin J, Brandelli A. Production, one-step purification, and characterization of a keratinolytic protease from Serratia marcescens P3. Process Biochem 2012. [DOI: 10.1016/j.procbio.2012.10.007] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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30
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Lipase and protease double-deletion mutant of Pseudomonas fluorescens suitable for extracellular protein production. Appl Environ Microbiol 2012; 78:8454-62. [PMID: 23042178 DOI: 10.1128/aem.02476-12] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Pseudomonas fluorescens, a widespread Gram-negative bacterium, is an ideal protein manufacturing factory (PMF) because of its safety, robust growth, and high protein production. P. fluorescens possesses a type I secretion system (T1SS), which mediates secretion of a thermostable lipase (TliA) and a protease (PrtA) through its ATP-binding cassette (ABC) transporter. Recombinant proteins in P. fluorescens are attached to the C-terminal signal region of TliA for transport as fusion proteins to the extracellular medium. However, intrinsic TliA from the P. fluorescens genome interferes with detection of the recombinant protein and the secreted recombinant protein is hydrolyzed, due to intrinsic PrtA, resulting in decreased efficiency of the PMF. In this research, the lipase and protease genes of P. fluorescens SIK W1 were deleted using the targeted gene knockout method. Deletion mutant P. fluorescens ΔtliA ΔprtA secreted fusion proteins without TliA or protein degradation. Using wild-type P. fluorescens as an expression host, degradation of the recombinant protein varied depending on the type of culture media and aeration; however, degradation did not occur with the P. fluorescens ΔtliA ΔprtA double mutant irrespective of growth conditions. By homologous expression of tliA and the ABC transporter in a plasmid, TliA secreted from P. fluorescens ΔprtA and P. fluorescens ΔtliA ΔprtA cells was found to be intact, whereas that secreted from the wild-type P. fluorescens and P. fluorescens ΔtliA cells was found to be hydrolyzed. Our results demonstrate that the P. fluorescens ΔtliA ΔprtA deletion mutant is a promising T1SS-mediated PMF that enhances production and detection of recombinant proteins in extracellular media.
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31
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Lewis VG, Ween MP, McDevitt CA. The role of ATP-binding cassette transporters in bacterial pathogenicity. PROTOPLASMA 2012; 249:919-942. [PMID: 22246051 DOI: 10.1007/s00709-011-0360-8] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Accepted: 11/29/2011] [Indexed: 05/31/2023]
Abstract
The ATP-binding cassette transporter superfamily is present in all three domains of life. This ubiquitous class of integral membrane proteins have diverse biological functions, but their fundamental role involves the unidirectional translocation of compounds across cellular membranes in an ATP coupled process. The importance of this class of proteins in eukaryotic systems is well established as typified by their association with genetic diseases and roles in the multi-drug resistance of cancer. In stark contrast, the ABC transporters of prokaryotes have not been exhaustively investigated due to the sheer number of different roles and organisms in which they function. In this review, we examine the breadth of functions associated with microbial ABC transporters in the context of their contribution to bacterial pathogenicity and virulence.
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Affiliation(s)
- Victoria G Lewis
- Research Centre for Infectious Diseases, School of Molecular and Biomedical Science, University of Adelaide, Adelaide, South Australia, 5005, Australia
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32
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Allison SD. A trait-based approach for modelling microbial litter decomposition. Ecol Lett 2012; 15:1058-70. [PMID: 22642621 DOI: 10.1111/j.1461-0248.2012.01807.x] [Citation(s) in RCA: 264] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Revised: 01/15/2012] [Accepted: 04/26/2012] [Indexed: 11/29/2022]
Abstract
Trait-based models are an emerging tool in ecology with the potential to link community dynamics, environmental responses and ecosystem processes. These models represent complex communities by defining taxa with trait combinations derived from prior distributions that may be constrained by trade-offs. Herein I develop a model that links microbial community composition with physiological and enzymatic traits to predict litter decomposition rates. This approach allows for trade-offs among traits that represent alternative microbial strategies for resource acquisition. The model predicts that optimal strategies depend on the level of enzyme production in the whole community, which determines resource availability and decomposition rates. There is also evidence for facilitation and competition among microbial taxa that co-occur on decomposing litter. These interactions vary with community investment in extracellular enzyme production and the magnitude of trade-offs affecting enzyme biochemical traits. The model accounted for 69% of the variation in decomposition rates of 15 Hawaiian litter types and up to 26% of the variation in enzyme activities. By explicitly representing diversity, trait-based models can predict ecosystem processes based on functional trait distributions in a community. The model developed herein illustrates that traits influencing microbial enzyme production are some of the key controls on litter decomposition rates.
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Affiliation(s)
- S D Allison
- Department of Ecology and Evolutionary Biology, Department of Earth System Science, University of California, Irvine, CA 92697, USA.
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33
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Nicolaisen MH, Worm J, Jørgensen NO, Middelboe M, Nybroe O. Proteinase production inPseudomonas fluorescensON2 is affected by carbon sources and allows surface-attached but not planktonic cells to utilize protein for growth in lake water. FEMS Microbiol Ecol 2012; 80:168-78. [DOI: 10.1111/j.1574-6941.2011.01285.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2011] [Revised: 11/30/2011] [Accepted: 12/15/2011] [Indexed: 11/30/2022] Open
Affiliation(s)
- Mette H. Nicolaisen
- Genetics and Microbiology Section; Department of Agriculture and Ecology; University of Copenhagen; Frederiksberg; Denmark
| | - Jakob Worm
- Genetics and Microbiology Section; Department of Agriculture and Ecology; University of Copenhagen; Frederiksberg; Denmark
| | - Niels O.G. Jørgensen
- Genetics and Microbiology Section; Department of Agriculture and Ecology; University of Copenhagen; Frederiksberg; Denmark
| | - Mathias Middelboe
- Marine Biological Section; Department of Biology; University of Copenhagen; Helsingør; Denmark
| | - Ole Nybroe
- Genetics and Microbiology Section; Department of Agriculture and Ecology; University of Copenhagen; Frederiksberg; Denmark
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34
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Role of extracellular protease in nitrogen substrate management during antibiotic fermentation: a process model and experimental validation. Appl Microbiol Biotechnol 2011; 91:1019-28. [DOI: 10.1007/s00253-011-3318-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2011] [Revised: 04/06/2011] [Accepted: 04/07/2011] [Indexed: 11/25/2022]
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35
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Proteolysis of casein micelles by Pseudomonas fluorescens CNRZ 798 contributes to the destabilisation of UHT milk during its storage. ACTA ACUST UNITED AC 2011. [DOI: 10.1007/s13594-011-0019-4] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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36
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van Rooyen J, Belrhali H, Abratt V, Sewell BT. Proteolysis of the type III glutamine synthetase from Bacteroides fragilis causes expedient crystal-packing rearrangements. Acta Crystallogr Sect F Struct Biol Cryst Commun 2011; 67:358-63. [PMID: 21393843 PMCID: PMC3053163 DOI: 10.1107/s1744309110053893] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2010] [Accepted: 12/22/2010] [Indexed: 11/10/2022]
Abstract
This work details the intentional modifications that led to the first structure of a type III glutamine synthetase enzyme (GSIII). This approach followed the serendipitous discovery of digestion caused by an extracellular protease from a contaminating bacterium, Pseudomonas fluorescens. The protease only cleaves the GSIII protein at a single site, leaving the oligomer intact but allowing the protein to crystallize in a different space group. This transition from space group P1 to space group C222(1) is accompanied by improved growth characteristics, more reproducible diffraction and enhanced mechanical stability. The crystallographic analyses presented here provide the structural basis of the altered molecular packing in the full-length and digested crystal forms and suggest modifications for future structural studies.
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Affiliation(s)
- Jason van Rooyen
- Electron Microscope Unit, Department of Molecular and Cell Biology, University of Cape Town, South Africa.
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37
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Linhartová I, Bumba L, Mašín J, Basler M, Osička R, Kamanová J, Procházková K, Adkins I, Hejnová-Holubová J, Sadílková L, Morová J, Sebo P. RTX proteins: a highly diverse family secreted by a common mechanism. FEMS Microbiol Rev 2011; 34:1076-112. [PMID: 20528947 PMCID: PMC3034196 DOI: 10.1111/j.1574-6976.2010.00231.x] [Citation(s) in RCA: 360] [Impact Index Per Article: 27.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Repeats-in-toxin (RTX) exoproteins of Gram-negative bacteria form a steadily growing family of proteins with diverse biological functions. Their common feature is the unique mode of export across the bacterial envelope via the type I secretion system and the characteristic, typically nonapeptide, glycine- and aspartate-rich repeats binding Ca2+ ions. In this review, we summarize the current state of knowledge on the organization of rtx loci and on the biological and biochemical activities of therein encoded proteins. Applying several types of bioinformatic screens on the steadily growing set of sequenced bacterial genomes, over 1000 RTX family members were detected, with the biological functions of most of them remaining to be characterized. Activities of the so far characterized RTX family members are then discussed and classified according to functional categories, ranging from the historically first characterized pore-forming RTX leukotoxins, through the large multifunctional enzymatic toxins, bacteriocins, nodulation proteins, surface layer proteins, up to secreted hydrolytic enzymes exhibiting metalloprotease or lipase activities of industrial interest.
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Affiliation(s)
- Irena Linhartová
- Institute of Microbiology AS CR v.v.i., Academy of Sciences of the Czech Republic, Prague, Czech Republic
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Wang F, Hao J, Yang C, Sun M. Cloning, Expression, and Identification of a Novel Extracellular Cold-Adapted Alkaline Protease Gene of the Marine Bacterium Strain YS-80-122. Appl Biochem Biotechnol 2010; 162:1497-505. [DOI: 10.1007/s12010-010-8927-y] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2009] [Accepted: 02/01/2010] [Indexed: 11/28/2022]
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Pinto UM, Costa ED, Mantovani HC, Vanetti MCD. The proteolytic activity of Pseudomonas Fluorescens 07A isolated from milk is not regulated by quorum sensing signals. Braz J Microbiol 2010; 41:91-6. [PMID: 24031468 PMCID: PMC3768619 DOI: 10.1590/s1517-838220100001000015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2008] [Revised: 03/30/2009] [Accepted: 08/22/2009] [Indexed: 11/24/2022] Open
Abstract
The proteolytic activity of Pseudomonas fluorescens 07A was investigated, and was optimal on tryptone-calcium medium. N-acyl-homoserine lactones (AHLs) were not detected on supernatants of late-exponential and stationary-phase culture broths. Synthetic AHLs or bacterial cell extracts added to the medium did not influence growth or proteolytic activity suggesting that quorum sensing might not regulate protease production in this strain.
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Affiliation(s)
- Uelinton M Pinto
- 363 Wing Hall, Department of Microbiology, Cornell University , Ithaca NY , U.S.A
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40
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Jankiewicz U, Szawłowska U, Sobańska M. Biochemical characterization of an alkaline metallopeptidase secreted by aPseudomonas fluorescensisolated from soil. J Basic Microbiol 2010; 50:125-34. [DOI: 10.1002/jobm.200900054] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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41
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Marchand S, Vandriesche G, Coorevits A, Coudijzer K, De Jonghe V, Dewettinck K, De Vos P, Devreese B, Heyndrickx M, De Block J. Heterogeneity of heat-resistant proteases from milk Pseudomonas species. Int J Food Microbiol 2009; 133:68-77. [PMID: 19481283 DOI: 10.1016/j.ijfoodmicro.2009.04.027] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2009] [Revised: 04/27/2009] [Accepted: 04/29/2009] [Indexed: 11/16/2022]
Abstract
Pseudomonas fragi, Pseudomonas lundensis and members of the Pseudomonas fluorescens group may spoil Ultra High Temperature (UHT) treated milk and dairy products, due to the production of heat-stable proteases in the cold chain of raw milk. Since the aprX gene codes for a heat-resistant protease in P. fluorescens, the presence of this gene has also been investigated in other members of the genus. For this purpose an aprX-screening PCR test has been developed. Twenty-nine representatives of important milk Pseudomonas species and thirty-five reference strains were screened. In 42 out of 55 investigated Pseudomonas strains, the aprX gene was detected, which proves the potential of the aprX-PCR test as a screening tool for potentially proteolytic Pseudomonas strains in milk samples. An extensive study of the obtained aprX-sequences on the DNA and the amino acid level, however, revealed a large heterogeneity within the investigated milk isolates. Although this heterogeneity sets limitations to a general detection method for all proteolytic Pseudomonas strains in milk, it offers a great potential for the development of a multiplex PCR screening test targeting individual aprX-genes. Furthermore, our data illustrated the potential use of the aprX gene as a taxonomic marker, which may help in resolving the current taxonomic deadlock in the P. fluorescens group.
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Affiliation(s)
- Sophie Marchand
- Institute for Agricultural and Fisheries Research, Melle, Belgium.
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Zhang WW, Hu YH, Wang HL, Sun L. Identification and characterization of a virulence-associated protease from a pathogenic Pseudomonas fluorescens strain. Vet Microbiol 2009; 139:183-8. [PMID: 19464828 DOI: 10.1016/j.vetmic.2009.04.026] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2009] [Revised: 04/17/2009] [Accepted: 04/24/2009] [Indexed: 11/17/2022]
Abstract
Pseudomonas fluorescens is an aquaculture pathogen that can infect a number of fish species. The virulence mechanisms of aquatic P. fluorescens remain largely unknown. Many P. fluorescens strains are able to secrete an extracellular protease called AprX, yet no AprX-like proteins have been identified in pathogenic P. fluorescens associated with aquaculture. In this study, a gene encoding an AprX homologue was cloned from TSS, a pathogenic P. fluorescens strain isolated from diseased fish. In TSS, AprX is secreted into the extracellular milieu, and the production of AprX is controlled by growth phase and calcium. Mutation of aprX has multiple effects, which include impaired abilities in interaction with cultured host cells, adherence to host mucus, modulation of host immune response, and dissemination and survival in host tissues and blood. Purified recombinant AprX exhibits apparent proteolytic activity, which is optimal at pH 8.0 and 50 degrees C. The protease activity of recombinant AprX is enhanced by Ca2+ and Zn2+ and reduced by Co2+. Cytotoxicity analyses showed that purified recombinant AprX has profound toxic effect on cultured fish cells. These results demonstrate that AprX is an extracellular metalloprotease that is involved in bacterial virulence.
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Affiliation(s)
- Wei-wei Zhang
- Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, PR China
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43
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Purification and properties of a heat-stable enzyme of Pseudomonas fluorescens Rm12 from raw milk. Eur Food Res Technol 2008. [DOI: 10.1007/s00217-008-0983-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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44
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Dufour D, Nicodème M, Perrin C, Driou A, Brusseaux E, Humbert G, Gaillard JL, Dary A. Molecular typing of industrial strains of Pseudomonas spp. isolated from milk and genetical and biochemical characterization of an extracellular protease produced by one of them. Int J Food Microbiol 2008; 125:188-96. [PMID: 18511140 DOI: 10.1016/j.ijfoodmicro.2008.04.004] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2008] [Revised: 03/27/2008] [Accepted: 04/01/2008] [Indexed: 11/16/2022]
Abstract
P. fluorescens is responsible for the highest depredation of milk because of its capacity to synthesize extracellular lipase and protease which hydrolyze milk fat and proteins. Several P. fluorescens synthesize an extracellular caseinolytic metalloprotease, called AprX. It is important to rapidly detect the presence of a contamination of raw milk by a strain, especially a P. fluorescens strain, having a high potential of depredation. If standard plate count procedures are often employed, they are time consuming and do not permit to rapidly evaluate the potential of depredation. An alternative method consists to search the aprX gene, but such a method remains of low sensitivity and does not allow evaluating the real potential of depredation of the contaminant. After a milk depredation event, three strains of Pseudomonas spp. (F, 2312 and 2313) have been isolated from a dairy plant. Using molecular and phenotypic approaches, these strains were identified as P. fluorescens strains. Their respective extracellular caseinolytic potential was characterized as well as that of several collection strains of P. fluorescens. It appeared that these strains secreted one protease of about 45 kDa, that their extracellular caseinolytic potential was highly variable for one strain to another and that the one of strain F was the highest. The protease secreted by the strain F was purified and its N-terminal sequence established. It shared 100% identity with the domain 14-34 of extracellular alkaline endoprotease sequences which are called AprX for some of them. Its gene was sequenced as well as that of two collection strains of P. fluorescens having a significant lower extracellular caseinolytic potential. The genomic environment of the aprX gene as well as its expression during the strain growth was investigated. It appears that the difference of extracellular caseinolytic potential which has been observed between the three strains does not mainly result from the AprX sequence/structure but it might rather result from the aprX level of expression.
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Affiliation(s)
- Delphine Dufour
- URAFPA, Nancy-Université, INRA, Equipe Protéolyse-Biofonctionnalité des Protéines et des Peptides, Boulevard des Aiguillettes, BP239, 54506 Vandoeuvre-lès-Nancy, France
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Sivaprakasam S, Mahadevan S, Sekar S. Calorimetric on-line monitoring of proteolytic activity of P. aeruginosa cultivated in a bench-scale biocalorimeter. Biochem Eng J 2008. [DOI: 10.1016/j.bej.2007.08.024] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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46
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Enhanced production and characterization of a solvent stable protease from solvent tolerant Pseudomonas aeruginosa PseA. Enzyme Microb Technol 2007. [DOI: 10.1016/j.enzmictec.2007.07.019] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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47
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Liehl P, Blight M, Vodovar N, Boccard F, Lemaitre B. Prevalence of local immune response against oral infection in a Drosophila/Pseudomonas infection model. PLoS Pathog 2006; 2:e56. [PMID: 16789834 PMCID: PMC1475658 DOI: 10.1371/journal.ppat.0020056] [Citation(s) in RCA: 192] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2006] [Accepted: 04/28/2006] [Indexed: 01/22/2023] Open
Abstract
Pathogens have developed multiple strategies that allow them to exploit host resources and resist the immune response. To study how Drosophila flies deal with infectious diseases in a natural context, we investigated the interactions between Drosophila and a newly identified entomopathogen, Pseudomonas entomophila. Flies orally infected with P. entomophila rapidly succumb despite the induction of both local and systemic immune responses, indicating that this bacterium has developed specific strategies to escape the fly immune response. Using a combined genetic approach on both host and pathogen, we showed that P. entomophila virulence is multi-factorial with a clear differentiation between factors that trigger the immune response and those that promote pathogenicity. We demonstrate that AprA, an abundant secreted metalloprotease produced by P. entomophila, is an important virulence factor. Inactivation of aprA attenuated both the capacity to persist in the host and pathogenicity. Interestingly, aprA mutants were able to survive to wild-type levels in immune-deficient Relish flies, indicating that the protease plays an important role in protection against the Drosophila immune response. Our study also reveals that the major contribution to the fly defense against P. entomophila is provided by the local, rather than the systemic immune response. More precisely, our data points to an important role for the antimicrobial peptide Diptericin against orally infectious Gram-negative bacteria, emphasizing the critical role of local antimicrobial peptide expression against food-borne pathogens. Normal feeding and digestion involves the ingestion of many microorganisms. Many are innocuous, some are commensal, and others may be pathogenic. Eukaryotes have thus evolved complex mechanisms to detect, control, and if necessary, eliminate intestinal microbes. Insects are no exception, and the fruit fly, Drosophila, employs a physical barrier within the intestinal lumen and the peritrophic matrix, and an innate immune response which exhibits similarities to the mammalian counterpart. Pseudomonas entomophila was identified as a novel entomopathogenic bacterium that can infect and colonize the gut of Drosophila. In this paper, Liehl et al. describe one specific secreted virulence factor of P. entomophila, the zinc metalloprotease, AprA, which they demonstrate to be required for defense against the host gut epithelial immune response. AprA defends P. entomophila against the Drosophila antimicrobial peptides, produced by the gut innate immune response. P. entomophila aprA mutants are attenuated for virulence in wild-type Drosophila but are equally infective as wild-type bacteria in immune-deficient mutant flies that do not express these antimicrobial peptides. Although secreted proteases have previously been described as a potentially important defense against host immune proteins, this is one of the rare examples of an in vivo demonstration of such a specific role against insect antimicrobial peptides.
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Affiliation(s)
- Peter Liehl
- Centre de Génétique Moléculaire, Centre National de la Rercheche Scientifique, Gif-sur-Yvette, France
| | - Mark Blight
- Centre de Génétique Moléculaire, Centre National de la Rercheche Scientifique, Gif-sur-Yvette, France
| | - Nicolas Vodovar
- Centre de Génétique Moléculaire, Centre National de la Rercheche Scientifique, Gif-sur-Yvette, France
| | - Frédéric Boccard
- Centre de Génétique Moléculaire, Centre National de la Rercheche Scientifique, Gif-sur-Yvette, France
| | - Bruno Lemaitre
- Centre de Génétique Moléculaire, Centre National de la Rercheche Scientifique, Gif-sur-Yvette, France
- * To whom correspondence should be addressed. E-mail:
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Nicodème M, Grill JP, Humbert G, Gaillard JL. Extracellular protease activity of different Pseudomonas strains: dependence of proteolytic activity on culture conditions. J Appl Microbiol 2006; 99:641-8. [PMID: 16108806 DOI: 10.1111/j.1365-2672.2005.02634.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIMS This study investigated the effect of growth conditions on proteolytic activity of a Pseudomonas strain, named Pseudomonas sp. LBSA1, isolated from bulk raw milk. It was compared with three Pseudomonas chlororaphis and one Pseudomonas fluorescens strain from culture collections. METHODS AND RESULTS Bacteriae were grown in a minimal salt medium. For all the strains, addition of 1% (v/v) skim milk to the growth medium was sufficient to induce protease production in 48-h culture. Addition of 1 mmol l(-1) calcium chloride permitted the detection of proteolytic activity of four strains in 48-h cultures but not for Pseudomonas sp. LBSA1. The five strains presented two patterns of proteolytic activity when grown in the minimal salt medium supplemented with 2% (v/v) skim milk at various temperatures for 48 h. Two electrophoretic protease patterns were also obtained from the zymogram of extracellular medium for the five strains. CONCLUSIONS The growth conditions permitting protease production are variable and do not depend on the genus of the producing strain. SIGNIFICANCE AND IMPACT OF THE STUDY For the first time a study on proteolytic activity of P. chlororaphis strains is reported. Among the tested criteria, zymograms of extracellular medium were the only ones that permitted distinguishing the P. chlororaphis strains from the P. fluorescens strain.
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Affiliation(s)
- M Nicodème
- Laboratoire des BioSciences de l'Aliment (LBSA), Faculté des Sciences et Techniques, Université Henri Poincaré-Nancy, 54506 Vandoeuvre-lès-Nancy Cedex, France
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Maunsell B, Adams C, O'Gara F. Complex regulation of AprA metalloprotease in Pseudomonas fluorescens M114: evidence for the involvement of iron, the ECF sigma factor, PbrA and pseudobactin M114 siderophore. Microbiology (Reading) 2006; 152:29-42. [PMID: 16385113 DOI: 10.1099/mic.0.28379-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In the soil bacterium Pseudomonas fluorescens M114, extracellular proteolytic activity and fluorescent siderophore (pseudobactin M114) production were previously shown to be co-ordinately negatively regulated in response to environmental iron levels. An iron-starvation extracytoplasmic function sigma factor, PbrA, required for the transcription of siderophore biosynthetic genes, was also implicated in M114 protease regulation. The current study centred on the characterization and genetic regulation of the gene(s) responsible for protease production in M114. A serralysin-type metalloprotease gene, aprA, was identified and found to encode the major, if not only, extracellular protease produced by this strain. The expression of aprA and its protein product were found to be subject to complex regulation. Transcription analysis confirmed that PbrA was required for full aprA transcription under low iron conditions, while the ferric uptake regulator, Fur, was implicated in aprA repression under high iron conditions. Interestingly, the iron regulation of AprA was dependent on culture conditions, with PbrA-independent AprA-mediated proteolytic activity observed on skim milk agar supplemented with yeast extract, when supplied with iron or purified pseudobactin M114. These effects were not observed on skim milk agar without yeast extract. PbrA-independent aprA expression was also observed from a truncated transcriptional fusion when grown in sucrose asparagine tryptone broth supplied with iron or purified pseudobactin M114. Thus, experimental evidence suggested that iron mediated its effects via transcriptional activation by PbrA under low iron conditions, while an as-yet-unidentified sigma factor(s) may be required for the PbrA-independent aprA expression and AprA proteolytic activity induced by siderophore and iron.
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Affiliation(s)
- Bláithín Maunsell
- The BIOMERIT Research Centre, Microbiology Dept, National University of Ireland, Cork, Ireland
| | - Claire Adams
- The BIOMERIT Research Centre, Microbiology Dept, National University of Ireland, Cork, Ireland
| | - Fergal O'Gara
- The BIOMERIT Research Centre, Microbiology Dept, National University of Ireland, Cork, Ireland
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Omori K, Idei A. Gram-negative bacterial ATP-binding cassette protein exporter family and diverse secretory proteins. J Biosci Bioeng 2005; 95:1-12. [PMID: 16233359 DOI: 10.1016/s1389-1723(03)80141-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2002] [Accepted: 08/05/2002] [Indexed: 10/27/2022]
Abstract
Protein translocation to the extracellular space is essential for the invasion, colonization, and survival of pathogenic gram-negative bacteria within a host organism. In addition to the N-terminal signal sequence-dependent secretion system, which is specific for protein transport to the periplasmic space, there are five major systems (type I, II, III, IV, and V) that are known to be involved in protein secretion into the extracellular space. Of the systems, the type I pathway, which is composed of three membrane components including an ATP-binding cassette (ABC) protein, translocates proteins into the extracellular space from the cytosol by directly using the energy generated from ATP hydrolysis, and therefore, the system is a member of the ABC transporter family and is also known as the ABC exporter. To date, ABC exporters have been discovered to be involved in the secretion of a wide variety of exoproteins including RTX (repeats-in-toxin) toxins, cell surface layer proteins, proteases, lipases, bacteriocins, heme-acquisition proteins, and nodulation-related proteins such as the exoglucanases of gram-negative bacteria. A secretory protein and its associated specific ABC exporter are encoded in the same gene cluster in most cases, and ABC exporters show substrate specificity for secretion. Consequently, ABC exporters are present based primarily on the number of secretory protein genes. A secretion signal is situated in the C-terminal region of secretory proteins, however, the characteristics of the secretion signal are not fully understood. Secretory substrates and their linked ABC exporters are reviewed in the following paper.
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Affiliation(s)
- Kenji Omori
- Discovery Research Laboratory, Tanabe Seiyaku Co., Ltd., Kawagishi-2-chome, Toda, Saitama 335-8505, Japan.
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