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Zou Z, Kaothien-Nakayama P, Nakayama H. Enhanced accumulation of γ-aminobutyric acid by deletion of aminotransferase genes involved in γ-aminobutyric acid catabolism in engineered Halomonas elongata. Appl Environ Microbiol 2024; 90:e0073424. [PMID: 39133003 PMCID: PMC11409643 DOI: 10.1128/aem.00734-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2024] [Accepted: 07/13/2024] [Indexed: 08/13/2024] Open
Abstract
Halomonas elongata OUT30018 is a moderately halophilic bacterium that synthesizes and accumulates ectoine as an osmolyte by activities of the enzymes encoded by the high salinity-inducible ectABC operon. Previously, we engineered a γ-aminobutyric acid (GABA)-producing H. elongata GOP-Gad (ΔectABC::mCherry-HopGadmut) from an ectoine-deficient mutant of this strain due to its ability to use high-salinity biomass waste as substrate. Here, to further increase GABA accumulation, we deleted gabT, which encodes GABA aminotransferase (GABA-AT) that catalyzes the first step of the GABA catabolic pathway, from the H. elongata GOP-Gad genome. The resulting strain H. elongata ZN3 (ΔectABC::mCherry-HopGadmut ΔgabT) accumulated 291 µmol/g cell dry weight (CDW) of GABA in the cells, which is a 1.5-fold increase from H. elongata GOP-Gad's 190 µmol/g CDW. This result has confirmed the role of GABA-AT in the GABA catabolic pathway. However, redundancy in endogenous GABA-AT activity was detected in a growth test, where a gabT-deletion mutant of H. elongata OUT30018 was cultured in a medium containing GABA as the sole carbon and nitrogen sources. Because L-2,4-diaminobutyric acid aminotransferase (DABA-AT), encoded by an ectB gene of the ectABC operon, shares sequence similarity with GABA-AT, a complementation analysis of the gabT and the ectB genes was performed in the H. elongata ZN3 genetic background to test the involvement of DABA-AT in the redundancy of GABA-AT activity. Our results indicate that the expression of DABA-AT can restore GABA-AT activity in H. elongata ZN3 and establish DABA-AT's aminotransferase activity toward GABA in vivo. IMPORTANCE In this study, we were able to increase the yield of GABA by 1.5 times in the GABA-producing H. elongata ZN3 strain by deleting the gabT gene, which encodes GABA-AT, the initial enzyme of the GABA catabolic pathway. We also report the first in vivo evidence for GABA aminotransferase activity of an ectB-encoded DABA-AT, confirming a longstanding speculation based on the reported in vitro GABA-AT activity of DABA-AT. According to our findings, the DABA-AT enzyme can catalyze the initial step of GABA catabolism, in addition to its known function in ectoine biosynthesis. This creates a cycle that promotes adequate substrate flow between the two pathways, particularly during the early stages of high-salinity stress response when the expression of the ectB gene is upregulated.
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Affiliation(s)
- Ziyan Zou
- Graduate School of Fisheries and Environmental Sciences, Nagasaki University, Nagasaki, Japan
| | - Pulla Kaothien-Nakayama
- Graduate School of Fisheries and Environmental Sciences, Nagasaki University, Nagasaki, Japan
| | - Hideki Nakayama
- Graduate School of Fisheries and Environmental Sciences, Nagasaki University, Nagasaki, Japan
- Institute of Integrated Science and Technology, Nagasaki University, Nagasaki, Japan
- Organization for Marine Science and Technology, Nagasaki University, Nagasaki, Japan
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Tsuji A, Takei Y, Azuma Y. Establishment of genetic tools for genomic DNA engineering of Halomonas sp. KM-1, a bacterium with potential for biochemical production. Microb Cell Fact 2022; 21:122. [PMID: 35725447 PMCID: PMC9208146 DOI: 10.1186/s12934-022-01797-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 04/13/2022] [Indexed: 01/09/2023] Open
Abstract
Halomonas species are halophilic and alkaliphilic bacteria, which exhibit potential for industrial production of a variety of chemicals, such as polyhydroxyalkanoates and ectoine, by fermentation because of their favorable characteristics, including high-density culturing capacity and low risk of contamination. However, genetic tools to modify the metabolism of Halomonas for suitable fermentation performance are limited. In this study, we developed two independent basic vectors for Halomonas, named pUCpHAw and pHA1AT_32, consisting of ori regions from two plasmids isolated from Halomonas sp. A020, and chloramphenicol- and tetracycline-resistant genes as cloning markers, respectively. These vectors can independently transform and co-transform the Halomonas sp. KM-1 (KM-1). A protein that was highly and constitutively accumulated was identified as a hemolysin coregulated protein (Hcp) based on proteome analysis of KM-1. Using the hcp promoter, various genes, such as phaA and EGFP, were highly expressed. To establish a gene disruption system, the Streptococcus pyogenes cas9 gene and guide RNA for the pyrF gene, a yeast URA3 homologue, were expressed in pUCpHAw and pHA1AT_32, respectively. As a result, gene disruption mutants were isolated based on phenotypes, 5-fluoroorotic acid resistance, and uracil auxotrophy. A combination of KM-1 and these vectors could be a suitable platform for industrial chemical and protein production.
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Affiliation(s)
- Ayaka Tsuji
- Graduate School of Biology-Oriented Science and Technology, Kindai University, Wakayama, Japan
| | - Yasuko Takei
- Graduate School of Biology-Oriented Science and Technology, Kindai University, Wakayama, Japan
| | - Yoshinao Azuma
- Graduate School of Biology-Oriented Science and Technology, Kindai University, Wakayama, Japan.
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3
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Halomonas as a chassis. Essays Biochem 2021; 65:393-403. [PMID: 33885142 PMCID: PMC8314019 DOI: 10.1042/ebc20200159] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 03/24/2021] [Accepted: 03/26/2021] [Indexed: 01/04/2023]
Abstract
With the rapid development of systems and synthetic biology, the non-model bacteria, Halomonas spp., have been developed recently to become a cost-competitive platform for producing a variety of products including polyesters, chemicals and proteins owing to their contamination resistance and ability of high cell density growth at alkaline pH and high salt concentration. These salt-loving microbes can partially solve the challenges of current industrial biotechnology (CIB) which requires high energy-consuming sterilization to prevent contamination as CIB is based on traditional chassis, typically, Escherichia coli, Bacillus subtilis, Pseudomonas putida and Corynebacterium glutamicum. The advantages and current status of Halomonas spp. including their molecular biology and metabolic engineering approaches as well as their applications are reviewed here. Moreover, a systematic strain engineering streamline, including product-based host development, genetic parts mining, static and dynamic optimization of modularized pathways and bioprocess-inspired cell engineering are summarized. All of these developments result in the term called next-generation industrial biotechnology (NGIB). Increasing efforts are made to develop their versatile cell factories powered by synthetic biology to demonstrate a new biomanufacturing strategy under open and continuous processes with significant cost-reduction on process complexity, energy, substrates and fresh water consumption.
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4
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Harris JR, Lundgren BR, Grzeskowiak BR, Mizuno K, Nomura CT. A rapid and efficient electroporation method for transformation of Halomonas sp. O-1. J Microbiol Methods 2016; 129:127-132. [PMID: 27542998 DOI: 10.1016/j.mimet.2016.08.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Revised: 08/15/2016] [Accepted: 08/15/2016] [Indexed: 11/27/2022]
Abstract
Halomonas sp. O-1 is a halophilic bacterium with a high potential for industrial application due to its natural ability to produce polyhydroxyalkanoates (PHAs) using seawater-based media. However, a major barrier preventing industrial scale implementation of this organism is a lack of molecular methodologies capable of readily transforming members of the Halomonas genus. Currently, the only reliable method used for introducing DNA into Halomonas spp. is bacterial conjugation, a somewhat tedious and time-consuming technique compared to electroporation-based methodologies. Here we describe a rapid and reproducible method for the electroporation of Halomonas sp. O-1 with plasmid DNA. Electrocompetent cells were generated by growing Halomonas sp. O-1 in a yeast extract-tryptone medium with a final salinity of 3.5%, pH of 7.5, followed by several washes using 300mM sucrose. Results show that plasmids containing chloramphenicol (Cm(R)) and gentamicin (Gm(R)) resistance cassettes are suitable antibiotic selection markers for transformation and yields of 10(4) transformants per μg of DNA were obtained. This method is simple to perform and the materials used are readily available in most research labs. Additionally, this plasmid-based transformation procedure has the potential to be adapted for a number of applications including the creation of recombinant stains and the generation of deletion mutants of Halomonas spp.
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Affiliation(s)
- Joshua R Harris
- Department of Chemistry, SUNY College of Environmental Science and Forestry, 1 Forestry Drive, Syracuse, NY 13210, USA
| | - Benjamin R Lundgren
- Department of Chemistry, SUNY College of Environmental Science and Forestry, 1 Forestry Drive, Syracuse, NY 13210, USA
| | - Brian R Grzeskowiak
- Department of Chemistry, SUNY College of Environmental Science and Forestry, 1 Forestry Drive, Syracuse, NY 13210, USA
| | - Kouhei Mizuno
- Department of Creative Engineering, National Institute of Technology, Kitakyushu College, 5-20-1 Shii, Kokuraminami-ku, Kitakyushu 802-0985, Japan
| | - Christopher T Nomura
- Department of Chemistry, SUNY College of Environmental Science and Forestry, 1 Forestry Drive, Syracuse, NY 13210, USA; Center for Applied Microbiology, SUNY College of Environmental Science and Forestry, 1 Forestry Drive, Syracuse, NY 13210, USA; Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, College of Life Sciences, Hubei University, Hubei Province, People's Republic of China.
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5
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Tanimura K, Matsumoto T, Nakayama H, Tanaka T, Kondo A. Improvement of ectoine productivity by using sugar transporter-overexpressing Halomonas elongata. Enzyme Microb Technol 2016; 89:63-8. [DOI: 10.1016/j.enzmictec.2016.03.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Revised: 02/12/2016] [Accepted: 03/16/2016] [Indexed: 10/22/2022]
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Yin J, Chen JC, Wu Q, Chen GQ. Halophiles, coming stars for industrial biotechnology. Biotechnol Adv 2014; 33:1433-42. [PMID: 25447783 DOI: 10.1016/j.biotechadv.2014.10.008] [Citation(s) in RCA: 163] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 10/10/2014] [Accepted: 10/19/2014] [Indexed: 10/24/2022]
Abstract
Industrial biotechnology aims to produce chemicals, materials and biofuels to ease the challenges of shortage on petroleum. However, due to the disadvantages of bioprocesses including energy consuming sterilization, high fresh water consumption, discontinuous fermentation to avoid microbial contamination, highly expensive stainless steel fermentation facilities and competing substrates for human consumption, industrial biotechnology is less competitive compared with chemical processes. Recently, halophiles have shown promises to overcome these shortcomings. Due to their unique halophilic properties, some halophiles are able to grow in high pH and high NaCl containing medium under higher temperature, allowing fermentation processes to run contamination free under unsterile conditions and continuous way. At the same time, genetic manipulation methods have been developed for halophiles. So far, halophiles have been used to produce bioplastics polyhydroxyalkanoates (PHA), ectoines, enzymes, and bio-surfactants. Increasing effects have been made to develop halophiles into a low cost platform for bioprocessing with advantages of low energy, less fresh water consumption, low fixed capital investment, and continuous production.
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Affiliation(s)
- Jin Yin
- MOE Key Lab of Bioinformatics, School of Life Science, Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing 100084, China
| | - Jin-Chun Chen
- MOE Key Lab of Bioinformatics, School of Life Science, Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing 100084, China
| | - Qiong Wu
- MOE Key Lab of Bioinformatics, School of Life Science, Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing 100084, China
| | - Guo-Qiang Chen
- MOE Key Lab of Bioinformatics, School of Life Science, Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing 100084, China.
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7
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Development of an enhanced chromosomal expression system based on porin synthesis operon for halophile Halomonas sp. Appl Microbiol Biotechnol 2014; 98:8987-97. [DOI: 10.1007/s00253-014-5959-1] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Revised: 07/11/2014] [Accepted: 07/14/2014] [Indexed: 01/26/2023]
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8
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Development of Halomonas TD01 as a host for open production of chemicals. Metab Eng 2014; 23:78-91. [PMID: 24566041 DOI: 10.1016/j.ymben.2014.02.006] [Citation(s) in RCA: 125] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2013] [Revised: 01/20/2014] [Accepted: 02/08/2014] [Indexed: 11/22/2022]
Abstract
Genetic engineering of Halomonas spp. was seldom reported due to the difficulty of genetic manipulation and lack of molecular biology tools. Halomonas TD01 can grow in a continuous and unsterile process without other microbial contaminations. It can be therefore exploited for economic production of chemicals. Here, Halomonas TD01 was metabolically engineered using the gene knockout procedure based on markerless gene replacement stimulated by double-strand breaks in the chromosome. When gene encoding 2-methylcitrate synthase in Halomonas TD01 was deleted, the conversion efficiency of propionic acid to 3-hydroxyvalerate (3HV) monomer fraction in random PHBV copolymers of 3-hydroxybutyrate (3HB) and 3HV was increased from around 10% to almost 100%, as a result, cells were grown to accumulate 70% PHBV in dry weight (CDW) consisting of 12mol% 3HV from 0.5g/L propionic acid in glucose mineral medium. Furthermore, successful deletions on three PHA depolymerases eliminate the possible influence of PHA depolymerases on PHA degradation in the complicated industrial fermentation process even though significant enhanced PHA content was not observed. In two 500L pilot-scale fermentor studies lasting 70h, the above engineered Halomonas TD01 grew to 112g/L CDW containing 70wt% P3HB, and to 80g/L CDW with 70wt% P(3HB-co-8mol% 3HV) in the presence of propionic acid. The cells grown in shake flasks even accumulated close to 92% PHB in CDW with a significant increase of glucose to PHB conversion efficiency from around 30% to 42% after 48h cultivation when pyridine nucleotide transhydrogenase was overexpressed. Halomonas TD01 was also engineered for producing a PHA regulatory protein PhaR which is a robust biosurfactant.
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9
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Tanimura K, Nakayama H, Tanaka T, Kondo A. Ectoine production from lignocellulosic biomass-derived sugars by engineered Halomonas elongata. BIORESOURCE TECHNOLOGY 2013; 142:523-529. [PMID: 23765002 DOI: 10.1016/j.biortech.2013.05.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Revised: 04/30/2013] [Accepted: 05/02/2013] [Indexed: 06/02/2023]
Abstract
In this study, the water-retaining cyclic amino acid ectoine was produced from a variety of sugars, including glucose, xylose, cellobiose, and glucose/xylose mixture using engineered Halomonas elongata. When grown on xylose as the sole carbon source, H. elongata produced 333 mmol/kg fresh cell weight (FW) of ectoine, which was 1.4-fold higher than that produced from glucose. To improve ectoine production, an ectD deficient H. elongata mutant was constructed. The engineered H. elongata produced 377 mmol/kg FW of ectoine from a glucose/xylose mixture. Ectoine was also produced from rice straw hydrolysate. These results show that H. elongata can produce ectoine from a variety of sugars derived from lignocellulosic biomass and thus has tremendous potential as a host for producing useful compounds from biomass resources.
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Affiliation(s)
- Kosuke Tanimura
- Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1, Rokkodai-Cho, Nada, Kobe 657-8501, Japan
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10
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Rodríguez-Moya J, Argandoña M, Iglesias-Guerra F, Nieto JJ, Vargas C. Temperature- and salinity-decoupled overproduction of hydroxyectoine by Chromohalobacter salexigens. Appl Environ Microbiol 2013; 79:1018-23. [PMID: 23160137 PMCID: PMC3568561 DOI: 10.1128/aem.02774-12] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2012] [Accepted: 11/09/2012] [Indexed: 12/24/2022] Open
Abstract
Hydroxyectoine overproduction by the natural producer Chromohalobacter salexigens is presented in this study. Genetically engineered strains were constructed that at low salinity coexpressed, in a vector derived from a native plasmid, the ectoine (ectABC) and hydroxyectoine (ectD) genes under the control of the ectA promoter, in a temperature-independent manner. Hydroxyectoine production was further improved by increasing the copies of ectD and using a C. salexigens genetic background unable to synthesize ectoines.
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Affiliation(s)
| | | | - Fernando Iglesias-Guerra
- Department of Organic and Pharmaceutical Chemistry, Faculty of Pharmacy, University of Seville, Seville, Spain
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11
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Tokunaga H, Arakawa T, Tokunaga M. Novel soluble expression technologies derived from unique properties of halophilic proteins. Appl Microbiol Biotechnol 2010; 88:1223-31. [DOI: 10.1007/s00253-010-2832-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2010] [Revised: 08/07/2010] [Accepted: 08/08/2010] [Indexed: 11/29/2022]
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12
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Llamas I, del Moral A, Martínez-Checa F, Arco Y, Arias S, Quesada E. Halomonas maura is a physiologically versatile bacterium of both ecological and biotechnological interest. Antonie van Leeuwenhoek 2006; 89:395-403. [PMID: 16622791 DOI: 10.1007/s10482-005-9043-9] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 11/21/2005] [Indexed: 11/27/2022]
Abstract
Halomonas maura is a bacterium of great metabolic versatility. We summarise in this work some of the properties that make it a very interesting microorganism both from an ecological and biotechnological point of view. It plays an active role in the nitrogen cycle, is capable of anaerobic respiration in the presence of nitrate and has recently been identified as a diazotrophic bacterium. Of equal interest is mauran, the exopolysaccharide produced by H. maura, which contributes to the formation of biofilms and thus affords the bacterium advantages in the colonisation of its saline niches. Mauran is highly viscous, shows thixotropic and pseudoplastic behaviour, has the capacity to capture heavy metals and exerts a certain immunomodulator effect in medicine. All these attributes have prompted us to make further investigations into its molecular characteristics. To date we have described 15 open reading frames (ORF's) related to exopolysaccharide production, nitrogen fixation and nitrate reductase activity among others.
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Affiliation(s)
- Inmaculada Llamas
- Department of Microbiology, University of Granada, Campus Universitario de Cartuja s/n, 18071, Granada, Spain
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Tokunaga H, Mitsuo K, Ichinose S, Omori A, Ventosa A, Nakae T, Tokunaga M. Salt-inducible multidrug efflux pump protein in the moderately halophilic bacterium Chromohalobacter sp. Appl Environ Microbiol 2004; 70:4424-31. [PMID: 15294769 PMCID: PMC492394 DOI: 10.1128/aem.70.8.4424-4431.2004] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
It has been known that halophilic bacteria often show natural resistance to antibiotics, dyes, and toxic metal ions, but the mechanism and regulation of this resistance have remained unexplained. We have addressed this question by identifying the gene responsible for multidrug resistance. A spontaneous ofloxacin-resistant mutant derived from the moderately halophilic bacterium Chromohalobacter sp. strain 160 showed a two- to fourfold increased resistance to structurally diverse compounds, such as tetracycline, cefsulodin, chloramphenicol, and ethidium bromide (EtBr), and tolerance to organic solvents, e.g., hexane and heptane. The mutant produced an elevated level of the 58-kDa outer membrane protein. This mutant (160R) accumulated about one-third the level of EtBr that the parent cells did. An uncoupler, carbonyl cyanide m-chlorophenylhydrazone, caused a severalfold increase in the intracellular accumulation of EtBr, with the wild-type and mutant cells accumulating nearly equal amounts. The hrdC gene encoding the 58-kDa outer membrane protein has been cloned. Disruption of this gene rendered the cells hypersusceptible to antibiotics and EtBr and led to a high level of accumulation of intracellular EtBr. The primary structure of HrdC has a weak similarity to that of Escherichia coli TolC. Interestingly, both drug resistance and the expression of HrdC were markedly increased in the presence of a high salt concentration in the growth medium, but this was not observed in hrdC-disrupted cells. These results indicate that HrdC is the outer membrane component of the putative efflux pump assembly and that it plays a major role in the observed induction of drug resistance by salt in this bacterium.
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Affiliation(s)
- Hiroko Tokunaga
- Laboratory of Applied and Molecular Microbiology, Faculty of Agriculture, Kagoshima University, 1-21-24 Korimoto, Kagoshima 890-0065, Japan
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Prabhu J, Schauwecker F, Grammel N, Keller U, Bernhard M. Functional expression of the ectoine hydroxylase gene (thpD) from Streptomyces chrysomallus in Halomonas elongata. Appl Environ Microbiol 2004; 70:3130-2. [PMID: 15128576 PMCID: PMC404422 DOI: 10.1128/aem.70.5.3130-3132.2004] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The formation of hydroxyectoine in the industrial ectoine producer Halomonas elongata was improved by the heterologous expression of the ectoine hydroxylase gene, thpD, from Streptomyces chrysomallus. The efficient conversion of ectoine to hydroxyectoine was achieved by the concerted regulation of thpD by the H. elongata ectA promoter.
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Affiliation(s)
- Julia Prabhu
- ActinoDrug Pharmaceuticals GmbH, 16761 Hennigsdorf, Germany
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15
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Tokunaga H, Ishibashi M, Arakawa T, Tokunaga M. Highly efficient renaturation of beta-lactamase isolated from moderately halophilic bacteria. FEBS Lett 2004; 558:7-12. [PMID: 14759507 DOI: 10.1016/s0014-5793(03)01508-4] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2003] [Revised: 12/08/2003] [Accepted: 12/10/2003] [Indexed: 11/29/2022]
Abstract
Most, if not all, beta-lactamases reported to date are irreversibly denatured at 60-70 degrees C. Here, we found that a halophilic beta-lactamase from the moderately halophilic bacterium Chromohalobacter sp. 560 was highly stable against heat inactivation: it retained approximately 75% of its activity after boiling for 5 min in the presence of 0.2 M NaCl, suggesting that the protein either incompletely denatures during the boiling process or readily renatures upon cooling to the assay temperature. Circular dichroism showed a complete unfolding at 60 degrees C and a full reversibility, indicating that the observed activity after boiling is due to efficient refolding following heat denaturation. The enzyme showed optimal activity at 50-60 degrees C, indicating that an increase in activity with temperature offsets the thermal denaturation. The gene bla was cloned, and the primary structure of the enzyme was deduced to be highly abundant in acidic amino acid residues, one of the characteristics of halophilic proteins. Despite its halophilic nature, the enzyme refolds in low salt media after heat denaturation.
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Affiliation(s)
- Hiroko Tokunaga
- Applied and Molecular Microbiology, Faculty of Agriculture, Kagoshima University, 1-21-24 Korimoto, Kagoshima 890-0065, Japan.
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16
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Argandoña M, Martínez-Checa F, Llamas I, Quesada E, del Moral A. Megaplasmids in Gram-negative, moderately halophilic bacteria. FEMS Microbiol Lett 2003; 227:81-6. [PMID: 14568151 DOI: 10.1016/s0378-1097(03)00651-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
We have discovered that many Halomonas species harbour large extrachromosomal DNA elements. Using currently available protocols it is technically very difficult to identify large plasmids in bacteria, and even more so when they are coated in mucous polysaccharide. We used culture conditions suitable for both halophilic and halophilic exopolysaccharide-producing bacteria and applied a modified gel electrophoresis method to locate and visualise the megaplasmids. Almost all the species of Halomonas studied harbour two plasmids of about 70 kb and 600 kb and some species carry other smaller extrachromosomal DNA elements. The common presence of these megaplasmids may well be related to the survival strategies of the bacteria in their special surroundings.
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Affiliation(s)
- Montserrat Argandoña
- Departamento de Microbiologi;a, Facultad de Farmacia, Campus Universitario de Cartuja s/n, 18071, Granada, Spain.
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17
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Llamas I, Suárez A, Quesada E, Béjar V, del Moral A. Identification and characterization of the carAB genes responsible for encoding carbamoylphosphate synthetase in Halomonas eurihalina. Extremophiles 2003; 7:205-11. [PMID: 12768451 DOI: 10.1007/s00792-002-0311-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2002] [Accepted: 12/02/2002] [Indexed: 10/28/2022]
Abstract
Halomonas eurihalina is a moderately halophilic bacterium which produces exopolysaccharides potentially of great use in many fields of industry and ecology. Strain F2-7 of H. eurihalina synthesizes an anionic exopolysaccharide known as polymer V2-7, which not only has emulsifying activity but also becomes viscous under acidic conditions, and therefore we consider it worthwhile making a detailed study of the genetics of this strain. By insertional mutagenesis using the mini-Tn 5 Km2 transposon we isolated and characterized a mutant strain, S36 K, which requires both arginine and uracil for growth and does not excrete EPS. S36 K carries a mutation within the carB gene that encodes the synthesis of the large subunit of the carbamoylphosphate synthetase enzyme, which in turn catalyzes the synthesis of carbamoylphosphate, an important precursor of arginine and pyrimidines. We describe here the cloning and characterization of the carAB genes, which encode carbamoylphosphate synthetase in Halomonas eurihalina, and discuss this enzyme's possible role in the pathways for the synthesis of exopolysaccharides in strain F2-7.
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Affiliation(s)
- Inmaculada Llamas
- Department of Microbiology, Faculty of Pharmacy, University of Granada, Campus Universitario de Cartuja, 18071 Granada, Spain
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Douka E, Christogianni A, Koukkou AI, Afendra AS, Drainas C. Use of a green fluorescent protein gene as a reporter in Zymomonas mobilis and Halomonas elongata. FEMS Microbiol Lett 2001; 201:221-7. [PMID: 11470365 DOI: 10.1111/j.1574-6968.2001.tb10760.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
We investigated the applicability of the green fluorescent protein of Aequorea victoria as a reporter for gene expression in the strictly fermentative Gram-negative ethanologenic bacterium Zymomonas mobilis and in the moderately halophilic bacterium Halomonas elongata. We have succeeded to express a mutated gene of green fluorescent protein under the control of different promoters in Z. mobilis and H. elongata grown under various glucose or salt concentrations, respectively. Our results demonstrate that gfp can serve as an easily assayable reporter gene in both organisms. Maximum fluorescence was obtained in Z. mobilis grown aerobically and in H. elongata grown under elevated salt concentration in solid medium. For both bacteria the fluorescence obtained was higher when the gfp gene was placed under the control of a native promoter.
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Affiliation(s)
- E Douka
- Sector of Organic Chemistry and Biochemistry, Department of Chemistry, University of Ioannina, 45110, Ioannina, Greece
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19
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Tegos G, Vargas C, Perysinakis A, Koukkou AI, Christogianni A, Nieto JJ, Ventosa A, Drainas C. Release of cell-free ice nuclei from Halomonas elongata expressing the ice nucleation gene inaZ of Pseudomonas syringae. J Appl Microbiol 2000; 89:785-92. [PMID: 11119152 DOI: 10.1046/j.1365-2672.2000.01180.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Release of ice nuclei in the growth medium of recombinant Halomonas elongata cells expressing the inaZ gene of Pseudomonas syringae was studied in an attempt to produce cell-free active ice nuclei for biotechnological applications. Cell-free ice nuclei were not retained by cellulose acetate filters of 0.2 microm pore size. Highest activity of cell-free ice nuclei was obtained when cells were grown in low salinity (0.5-5% NaCl, w/v). Freezing temperature threshold, estimated to be below -7 degrees C indicating class C nuclei, was not affected by medium salinity. Their density, as estimated by Percoll density centrifugation, was 1.018 +/- 0.002 gml(-1) and they were found to be free of lipids. Ice nuclei are released in the growth medium of recombinant H. elongata cells probably because of inefficient anchoring of the ice-nucleation protein aggregates in the outer membrane. The ice+ recombinant H. elongata cells could be useful for future use as a source of active cell-free ice nucleation protein.
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Affiliation(s)
- G Tegos
- Department of Chemistry, University of Ioannina, Greece
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20
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Vargas C, Tegos G, Vartholomatos G, Drainas C, Ventosa A, Nieto JJ. Genetic organization of the mobilization region of the plasmid pHE1 from Halomonas elongata. Syst Appl Microbiol 1999; 22:520-9. [PMID: 10794139 DOI: 10.1016/s0723-2020(99)80004-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
The mobilization (mob) region of the non-self transmissible 4.2-kb plasmid pHE1 from the moderately halophilic bacterium Halomonas elongata ATCC 33174 has been identified and characterized. Analysis of the sequence revealed the presence of four open reading frames (mobCABD) which show a complex organization with two of them (mobB and mobD) entirely overlapped by a third (mobA). The deduced proteins appeared to have a high degree of homology to Mob proteins of CoIE1 and closely related plasmids. To assess the functionality of the mob region, the hybrid vector pHS134 was constructed, consisting of the complete plasmid pHEI, the E. coli vector pKS(-) and a streptomycin-resistance gene for positive selection in Halomonas. Vector pHS134 was found to be mobilizable from E. coli to H. elongata assisted by pRK600. Upstream of the mob genes, an oriT region with a putative nick sequence highly homologous to that of CoIE1 plasmids was identified. To our knowledge, this is the first mobilizable plasmid found in moderate halophiles. This property, together with its small size, the availability of its complete sequence, and its broad host range in moderately halophilic strains, makes pHE1 a good candidate for the construction of cloning and expression vectors for these extremophiles.
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Affiliation(s)
- C Vargas
- Department of Microbiology and Parasitology, Faculty of Pharmacy, University of Seville, Spain
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21
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Abstract
Seventeen alkaliphilic halomonads were examined for the presence of plasmids. Of these, eight strains harbored one or more from 5.3 to 33 kb in size, the first plasmids to be identified from an alkaliphilic halomonad source. Restriction and hybridization analysis revealed three strains that maintained an identical 5.9-kb plasmid which we named pAH1, two that had an identical 33-kb plasmid, and three others, of which one carried two plasmids of 5.3 and 15 kb, the former being designated pAH2. The two final strains maintained plasmids of 15 and 20.5 kb. Restriction mapping of both pAH1 and pAH2 indicated that they have a number of unique restriction sites and are of a small enough size to make them suitable for vector construction.
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Affiliation(s)
- S A Fish
- Department of Microbiology and Immunology, University of Leicester, Maurice Shock Building, Leicester, LE1 9HN, United Kingdom
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22
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Abstract
The moderately halophilic heterotrophic aerobic bacteria form a diverse group of microorganisms. The property of halophilism is widespread within the bacterial domain. Bacterial halophiles are abundant in environments such as salt lakes, saline soils, and salted food products. Most species keep their intracellular ionic concentrations at low levels while synthesizing or accumulating organic solutes to provide osmotic equilibrium of the cytoplasm with the surrounding medium. Complex mechanisms of adjustment of the intracellular environments and the properties of the cytoplasmic membrane enable rapid adaptation to changes in the salt concentration of the environment. Approaches to the study of genetic processes have recently been developed for several moderate halophiles, opening the way toward an understanding of haloadaptation at the molecular level. The new information obtained is also expected to contribute to the development of novel biotechnological uses for these organisms.
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Affiliation(s)
- A Ventosa
- Department of Microbiology and Parasitology, Faculty of Pharmacy, University of Seville, 41012 Seville, Spain.
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23
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Louis P, Galinski EA. Identification of plasmids in the genus Marinococcus and complete nucleotide sequence of plasmid pPL1 from Marinococcus halophilus. Plasmid 1997; 38:107-14. [PMID: 9339468 DOI: 10.1006/plas.1997.1304] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Several plasmids were detected in the Gram-positive halophilic eubacterium Marinococcus halophilus and in the related strain M52. The complete nucleotide sequence (3874 bp) of one of these plasmids, pPL1, was determined. Four major open reading frames were identified. Whereas orf3 and orf4 showed no sequence similarities to known proteins, rep displayed a high sequence similarity to replication proteins of rolling circle plasmids. Upstream of this ORF, a sequence resembling the double-strand origin was detected. A region probably constituting the single-strand origin was identified. The ORF mob showed sequence similarity with Mob proteins of rolling circle plasmids. The observed characteristics suggest that pPL1 replicates according to the rolling circle mechanism.
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Affiliation(s)
- P Louis
- Institut für Mikrobiologie & Biotechnologie, Rheinische Friedrich-Wilhelms-Universität Bonn, Germany
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24
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Cánovas D, Vargas C, Iglesias-Guerra F, Csonka LN, Rhodes D, Ventosa A, Nieto JJ. Isolation and characterization of salt-sensitive mutants of the moderate halophile Halomonas elongata and cloning of the ectoine synthesis genes. J Biol Chem 1997; 272:25794-801. [PMID: 9325308 DOI: 10.1074/jbc.272.41.25794] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The moderate halophile Halomonas elongata Deustche Sammlung für Mikroorganismen 3043 accumulated ectoine, hydroxyectoine, glutamate, and glutamine in response to osmotic stress (3 M NaCl). Two Tn1732-induced mutants, CHR62 and CHR63, that were severely affected in their salt tolerance were isolated. Mutant CHR62 could not grow above 0.75 M NaCl, and CHR63 did not grow above 1.5 M NaCl. These mutants did not synthesize ectoine but accumulated ectoine precursors, as shown by 13C NMR and mass spectroscopy. Mutant CHR62 accumulated low levels of diaminobutyric acid, and mutant CHR63 accumulated high concentrations of N-gamma-acetyldiaminobutyric acid. These results suggest that strain CHR62 could be defective in the gene for diaminobutyric acid acetyltransferase (ectB), and strain CHR63 could be defective in the gene for the ectoine synthase (ectC). Salt sensitivity of the mutants at 1.5-2.5 M NaCl could be partially corrected by cytoplasmic extracts of the wild-type strain, containing ectoine, and salt sensitivity of strain CHR62 could be partially repaired by the addition of extracts of strain CHR63, which contained N-gamma-acetyldiaminobutyric acid. This is the first evidence for the role of N-gamma-acetyldiaminobutyric acid as osmoprotectant. Finally, a cosmid from the H. elongata genomic library was isolated which complemented the Ect- phenotype of both mutants, indicating that it carried at least the genes ectB and ectC of the biosynthetic pathway of ectoine.
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Affiliation(s)
- D Cánovas
- Department of Microbiology and Parasitology, Faculty of Pharmacy, University of Seville, 41012 Seville, Spain
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Host Range, Stability and Compatibility of Broad Host-Range-Plasmids and a Shuttle Vector in Moderately Halophilic Bacteria. Evidence of Intrageneric and Intergeneric Conjugation in Moderate Halophiles. Syst Appl Microbiol 1997. [DOI: 10.1016/s0723-2020(97)80063-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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26
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Analysis of the Genome of Vibrio costicola: Pulsed-Field Gel Electrophoretic Analysis of Genome Size and Plasmid Content. Syst Appl Microbiol 1997. [DOI: 10.1016/s0723-2020(97)80044-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Coronado MJ, Vargas C, Kunte HJ, Galinski EA, Ventosa A, Nieto JJ. Influence of salt concentration on the susceptibility of moderately halophilic bacteria to antimicrobials and its potential use for genetic transfer studies. Curr Microbiol 1995; 31:365-71. [PMID: 8528008 DOI: 10.1007/bf00294701] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The influence of salinity on the susceptibility of 13 moderately halophilic collection strains belonging to the genera Chromohalobacter, Deleya, Halomonas, Vibrio, and Volcaniella to 10 common antimicrobials has been studied. Three different patterns of tolerance were found when salinity was varied from 10 to 1% (wt/vol) total salts in the testing media. The first one included the responses to ampicillin and rifampicin, where only minimal effects on the susceptibility were found. All moderate halophiles showed a high sensitivity to rifampicin regardless of the salt concentration. In the second group, including the responses to the aminoglycosides gentamycin, kanamycin, neomycin, and streptomycin, a remarkable and gradual increase of the toxicity was detected at lower salinities. Thirdly, the highest heterogeneity was found for the rest of antimicrobials assayed (trimethoprim, nalidixic acid, spectinomycin, and tetracycline), where the effect of salinity was moderate and dependent on both the individual strain and the antimicrobial tested. The data presented here should facilitate genetic studies on moderate halophiles. Thus, they simplify the design of selection media for genetic exchange experiments. Besides, by using low-salinity media, genes encoding resistance to a number of antimicrobials, especially to aminoglycosides, can be used as genetic markers for plasmids or transposons to be transferred to these extremophiles.
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Affiliation(s)
- M J Coronado
- Department of Microbiology and Parasitology, Faculty of Pharmacy, University of Sevilla, Spain
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28
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Arvanitis N, Vargas C, Tegos G, Perysinakis A, Nieto JJ, Ventosa A, Drainas C. Development of a gene reporter system in moderately halophilic bacteria by employing the ice nucleation gene of Pseudomonas syringae. Appl Environ Microbiol 1995; 61:3821-5. [PMID: 8526492 PMCID: PMC167685 DOI: 10.1128/aem.61.11.3821-3825.1995] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The expression of the ice nucleation gene inaZ of Pseudomonas syringae in several moderate halophiles was investigated to establish its utility as a reporter for promoter activity and gene expression studies in these biotechnologically and environmentally important bacteria. A promoterless version of inaZ was introduced in two different restriction sites and at both orientations in a recombinant plasmid able to replicate in moderate halophiles and, in particular, within the sequence of its pHE1 part, a native plasmid of Halomonas elongata. One orientation of both recombinant constructs expressed high levels of ice nucleation activity in H. elongata and Volcaniella eurihalina cells, indicating that inaZ was probably introduced in the correct orientation downstream of putative native promoters. A recombinant construct carrying a tandem duplication of inaZ at the same orientation gave significantly higher ice nucleation activity, showing that inaZ is appropriate for gene dosage studies. The ice nucleation gene was also expressed in H. elongata and V. eurihalina under the control of Pbla (the promoter of the beta-lactamase gene of Escherichia coli) and Ppdc (the promoter of the pyruvate decarboxylase gene of Zymomonas mobilis). One of the inaZ reporter plasmids expressing high levels of ice nucleation activity under the control of a native putative promoter was also transferred in Halomonas subglaciescola, Halomonas meridiana, Halomonas halodurans, and Deleya halophila. In all cases, Ice+ transconjugants were successfully isolated, demonstrating that inaZ is expressed in a wide spectrum of moderately halophilic species.
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Affiliation(s)
- N Arvanitis
- Department of Chemistry, University of Ioannina, Greece
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