Influence of growth conditions on the production of extracellular proteolytic enzymes in Paenibacillus peoriae NRRL BD-62 and Paenibacillus polymyxa SCE2

Hexanic extract of Achyrocline satureioides: antimicrobial activity and in vitro inhibitory effect on mechanisms related to the pathogenicity of Paenibacillus larvae

INTRODUCTION

Paenibacillus larvae is a spore-forming bacillus, the most important bacterial pathogen of honeybee larvae and the causative agent of American foulbrood (AFB). Control measures are limited and represent a challenge for both beekeepers and researchers. For this reason, many studies focus on the search for alternative treatments based on natural products.

AIM

The objective of this study was to determine the antimicrobial activity of the hexanic extract (HE) of Achyrocline satureioides on P. larvae and the inhibitory activity on some mechanisms related to pathogenicity.

MATERIAL AND METHODS

The Minimum Inhibitory Concentration (MIC) of the HE was determined by the broth microdilution technique and the Minimum Bactericidal Concentration (MBC) by the microdrop technique. Swimming and swarming motility was evaluated in plates with 0.3 and 0.5% agar, respectively. Biofilm formation was evaluated and quantified by the Congo red and crystal violet method. The protease activity was evaluated by the qualitative technique on skim milk agar plates.

RESULTS

It was determined that the MIC of the HE on four strains of P. larvae ranged between 0.3 and 9.37 µg/ml and the MBC between 1.17 and 150 µg/ml. On the other hand, sub-inhibitory concentrations of the HE were able to decrease swimming motility, biofilm formation and the proteases production of P. larvae.

Development of a chemically defined medium for Paenibacillus polymyxa by parallel online monitoring of the respiration activity in microtiter plates

BACKGROUND

One critical parameter in microbial cultivations is the composition of the cultivation medium. Nowadays, the application of chemically defined media increases, due to a more defined and reproducible fermentation performance than in complex media. In order, to improve cost-effectiveness of fermentation processes using chemically defined media, the media should not contain nutrients in large excess. Additionally, to obtain high product yields, the nutrient concentrations should not be limiting. Therefore, efficient medium optimization techniques are required which adapt medium compositions to the specific nutrient requirements of microorganisms.

RESULTS

Since most Paenibacillus cultivation protocols so far described in literature are based on complex ingredients, in this study, a chemically defined medium for an industrially relevant Paenibacillus polymyxa strain was developed. A recently reported method, which combines a systematic experimental procedure in combination with online monitoring of the respiration activity, was applied and extended to identify growth limitations for Paenibacillus polymyxa. All cultivations were performed in microtiter plates. By systematically increasing the concentrations of different nutrient groups, nicotinic acid was identified as a growth-limiting component. Additionally, an insufficient buffer capacity was observed. After optimizing the growth in the chemically defined medium, the medium components were systematically reduced to contain only nutrients relevant for growth. Vitamins were reduced to nicotinic acid and biotin, and amino acids to methionine, histidine, proline, arginine, and glutamate. Nucleobases/-sides could be completely left out of the medium. Finally, the cultivation in the reduced medium was reproduced in a laboratory fermenter.

CONCLUSION

In this study, a reliable and time-efficient high-throughput methodology was extended to investigate limitations in chemically defined media. The interpretation of online measured respiration activities agreed well with the growth performance of samples measured in parallel via offline analyses. Furthermore, the cultivation in microtiter plates was validated in a laboratory fermenter. The results underline the benefits of online monitoring of the respiration activity already in the early stages of process development, to avoid limitations of medium components, oxygen limitation and pH inhibition during the scale-up.

Integrated genomics and proteomics analysis of Paenibacillus peoriae IBSD35 and insights into its antimicrobial characteristics

Antimicrobial resistance has been developing fast and incurring a loss of human life, and there is a need for new antimicrobial agents. Naturally occurring antimicrobial peptides offer the characteristics to counter AMR because the resistance development is low or no resistance. Antimicrobial peptides from Paenibacillus peoriae IBSD35 cell-free supernatant were salted out and purified using chromatography and characterized with liquid chromatography-tandem-mass spectrometry. The extract has shown a high and broad spectrum of antimicrobial activity. Combining the strain IBSD35 genome sequence with its proteomic data enabled the prediction of biosynthetic gene clusters by connecting the peptide from LC-MS/MS data to the gene that encode. Antimicrobial peptide databases offered a platform for the effective search, prediction, and design of AMPs and expanded the studies on their isolation, structure elucidation, biological evaluation, and pathway engineering. The genome-based taxonomy and comparisons have shown that P. peoriae IBSD35 is closely related to Paenibacillus peoriae FSL J3-0120. P. peoriae IBSD35 harbored endophytic trait genes and nonribosomal peptide synthases biosynthetic gene clusters. The comparative genomics revealed evolutionary insights and facilitated the discovery of novel SMs using proteomics from the extract of P. peoriae IBSD35. It will increase the potential to find novel bio-molecules to counter AMR.

Proteases Production and Chitin Preparation from the Liquid Fermentation of Chitinous Fishery By-Products by Paenibacillus elgii

Chitinous fishery by-products have great application in the production of various bioactive compounds. In this study, Paenibacillus elgii TKU051, a protease-producing bacterial strain, was isolated using a medium containing 1% squid pens powder (SPP) as the sole carbon/nitrogen (C/N) source. P. elgii TKU051 was found to produce at least four proteases with molecular weights of 100 kDa, 57 kDa, 43 kDa, and 34 kDa (determined by the gelatin zymography method). A P. elgii TkU051 crude enzyme cocktail was optimally active at pH 6-7 and 60 °C. The 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity and α-glucosidase inhibitory activity of the hydrolysates obtained from the hydrolysis of shrimp shell powder, shrimp head powder, shrimp meat powder, fish head powder and soya bean powder catalyzed by the P. elgii TkU051 crude enzyme cocktail were also evaluated. P. elgii TKU051 exhibited a high deproteinization capacity (over 94%) on different kinds of shrimp waste (shrimp heads and shells; fresh and cooked shrimp waste; shrimp waste dried by oven and lyophilizer), and the Fourier-transform infrared spectroscopy profile of the chitin obtained from the deproteinization process displayed the characteristic of chitin. Finally, the obtained chitin exhibited an effect comparable to commercial chitin in terms of adsorption against Congo Red (90.48% and 90.91%, respectively). Thus, P. elgii TKU051 showed potential in the reclamation of chitinous fishery by-products for proteases production and chitin extraction.

From Donor to the Lab: A Fascinating Journey of Primary Cell Lines

Primary cancer cell lines are ex vivo cell cultures originating from resected tissues during biopsies and surgeries. Primary cell cultures are objects of intense research due to their high impact on molecular biology and oncology advancement. Initially, the patient-derived specimen must be subjected to dissociation and isolation. Techniques for tumour dissociation are usually reliant on the organisation of connecting tissue. The most common methods include enzymatic digestion (with collagenase, dispase, and DNase), chemical treatment (with ethylene diamine tetraacetic acid and ethylene glycol tetraacetic acid), or mechanical disaggregation to obtain a uniform cell population. Cells isolated from the tissue specimen are cultured as a monolayer or three-dimensional culture, in the form of multicellular spheroids, scaffold-based cultures (i.e., organoids), or matrix-embedded cultures. Every primary cell line must be characterised to identify its origin, purity, and significant features. The process of characterisation should include different assays utilising specific (extra- and intracellular) markers. The most frequently used approaches comprise immunohistochemistry, immunocytochemistry, western blot, flow cytometry, real-time polymerase chain reaction, karyotyping, confocal microscopy, and next-generation sequencing. The growing body of evidence indicates the validity of the usage of primary cancer cell lines in the formulation of novel anti-cancer treatments and their contribution to drug development.

Paenibacillus polymyxa, a Jack of all trades

The bacterium Paenibacillus polymyxa is found naturally in diverse niches. Microbiome analyses have revealed enrichment in the genus Paenibacillus in soils under different adverse conditions, which is often accompanied by improved growth conditions for residing plants. Furthermore, Paenibacillus is a member of the core microbiome of several agriculturally important crops, making its close association with plants an interesting research topic. This review covers the versatile interaction possibilities of P. polymyxa with plants and its applicability in industry and agriculture. Thanks to its array of produced compounds and traits, P. polymyxa is likely an efficient plant growth-promoting bacterium, with the potential of biofertilization, biocontrol and protection against abiotic stresses. By contrast, cases of phytotoxicity of P. polymyxa have been described as well, in which growth conditions seem to play a key role. Because of its adjustable character, we propose this bacterial species as an outstanding model for future studies on host-microbe communications and on the manner how the environment can influence these interactions.

Enzymatic hydrolysis using bacterial cultures as a novel method for obtaining antioxidant peptides from brewers' spent grain

Brewers' spent grain was used as a substrate to obtain protein hydrolysates with antioxidant activity. Hydrolysis was conducted in the culture using proteolytic bacteria. Hydrolysis was controlled by measurement of α-amino group concentration and with the aid of size exclusion chromatography. For each culture the degree of hydrolysis was calculated. The most efficient protein hydrolysis was observed in the cultures of Bacillus cereus (43.06%) and Bacillus lentus (41.81%). In addition, gelatin zymography was performed in order to detect bacterial proteases and their activity. The profile of secreted enzymes was heterogeneous, while the greatest variety was observed for Bacillus polymyxa. Brewers' spent grain protein hydrolysates exhibited high antioxidant activity. Bacillus subtilis and Bacillus cereus post-cultured media displayed the highest activity, respectively 1291.97 and 1621.31 μM TEAC per g for ABTS, 188.89 and 160.93 μM TEAC per g for DPPH, and 248.81 and 284.08 μM TEAC per g for the FRAP method.

Hydrolysis of brewers' spent grain conducted in the bacterial cultures entails reduction of workload, economic cost and environmental impact.

Utilization of Seafood Processing By-Products for Production of Proteases by Paenibacillus sp. TKU052 and Their Application in Biopeptides' Preparation

Microbial fermentation of by-products is a renewable and efficient technique in the development of a range of useful products. In this study, protease synthesis by Paenibacillus sp. TKU052 was carried out on culture media containing some common seafood processing by-products (SPBPs) as the sole source of carbon and nitrogen (C/N). The most suitable C/N nutrition source for the production of proteases was found to be 3.0% (w/v) demineralized crab shells powder (deCSP) and maximal enzyme activity of 4.41 ± 0.16 U/mL was detected on the third day of the culture. Two proteases (P1 and P2) with a similar molecular weight of 31 kDa were successfully isolated and purified from the 3-day deCSP-containing medium. Both P1 and P2 exhibited the highest activity of gelatin hydrolysis at pH 6 and 60 °C. The gelatin hydrolysates catalyzed by Paenibacillus TKU052 proteases were evaluated for biological activities, including 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, angiotensin-I converting enzyme (ACE) inhibition, and prebiotic activities. The gelatin hydrolysates expressed 31.76–43.95% DPPH radical scavenging activity and 31.58–36.84% ACE inhibitory activity, which was higher than those from gelatin. Gelatin hydrolysates also showed the growth-enhancing effect on Bifidobacterium bifidum BCRC 14615 with an increase to 135.70–147.81%. In short, Paenibacillus sp. TKU052 could be a potential strain to utilize crab shell wastes to produce proteases for bio-active peptides’ preparation.

Microbial Conversion of Shrimp Heads to Proteases and Chitin as an Effective Dye Adsorbent

As a green and effective technique in the production of a large number of valuable products, the microbial conversion of chitinous fishery wastes is receiving much attention. In this study, protease production using the Paenibacillus mucilaginosus TKU032 strain was conducted on culture media containing several common types of chitinous fishery by-products serving as the carbon and nitrogen (C/N) nutrition source. Among the chitinous wastes, 1.5% (w/v) shrimp head powder (SHP) was found to be the most appropriate nutritional source for protease production when a maximal enzyme activity of 3.14 ± 0.1 U/mL was observed on the 3rd day of the culture period. The molecular mass of P. mucilaginosus TKU032 protease was estimated to be nearly 32 kDa by the polyacrylamide gel electrophoresis method. The residual SHP obtained from the culture medium was also considered to be utilized for chitin extraction. The deproteinization rate of the fermentation was estimated to be 45%, and the chitin obtained from fermented SHP (fSHP) displayed a similar characteristic Fourier-transform infrared spectroscopy (FTIR) profile as that from SHP. In addition, SHP, fSHP, and chitins obtained from SHP and fSHP were investigated for their adsorptive capacity of nine types of dyes, and chitin obtained from fSHP displayed a good adsorption rate on Congo Red and Red No. 7, at 99% and 97%, respectively. In short, the results provide potential support for the utilization of SHP in the production of P. mucilaginosus TKU032 protease via the fermentation as well as the preparation of chitin from fSHP as an effective dye adsorbent.

Draft Genome Sequence of Bacillus sp. Strain EKM601B (Phylum Firmicutes), Living inside the Seeds of Luffa acutangula (Chinese Okra)

Presented here is the draft genome sequence of Bacillus sp. strain EKM601B, which contains 4,199,360 bp in 73 contigs. This candidate endophyte was isolated from surface-sterilized dry seeds of Luffa acutangula (Chinese okra) and demonstrated diverse plant-beneficial functions and antagonism against soilborne pathogens in vitro.

Presented here is the draft genome sequence of Bacillus sp. strain EKM601B, which contains 4,199,360 bp in 73 contigs. This candidate endophyte was isolated from surface-sterilized dry seeds of Luffa acutangula (Chinese okra) and demonstrated diverse plant-beneficial functions and antagonism against soilborne pathogens in vitro.

Cold tolerance response mechanisms revealed through comparative analysis of gene and protein expression in multiple rice genotypes

Due to its tropical origin and adaptation, rice is significantly impacted by cold stress, and consequently sustains large losses in growth and productivity. Currently, rice is the second most consumed cereal in the world and production losses caused by extreme temperature events in the context of "major climatic changes" can have major impacts on the world economy. We report here an analysis of rice genotypes in response to low-temperature stress, studied through physiological gas-exchange parameters, biochemical changes in photosynthetic pigments and antioxidants, and at the level of gene and protein expression, towards an understanding and identification of multiple low-temperature tolerance mechanisms. The first effects of cold stress were observed on photosynthesis among all genotypes. However, the tropical japonica genotypes Secano do Brazil and Cypress had a greater reduction in gas exchange parameters like photosynthesis and water use efficiency in comparison to the temperate japonica Nipponbare and M202 genotypes. The analysis of biochemical profiles showed that despite the impacts of low temperature on tolerant plants, they quickly adjusted to maintain their cellular homeostasis by an accumulation of antioxidants and osmolytes like phenolic compounds and proline. The cold tolerant and sensitive genotypes showed a clear difference in gene expression at the transcript level for OsGH3-2, OsSRO1a, OsZFP245, and OsTPP1, as well as for expression at the protein level for LRR-RLKs, bHLH, GLYI, and LTP1 proteins. This study exemplifies the cold tolerant features of the temperate japonica Nipponbare and M202 genotypes, as observed through the analysis of physiological and biochemical responses and the associated changes in gene and protein expression patterns. The genes and proteins showing differential expression response are notable candidates towards understanding the biological pathways affected in rice and for engineering cold tolerance, to generate cultivars capable of maintaining growth, development, and reproduction under cold stress. We also propose that the mechanisms of action of the genes analyzed are associated with the tolerance response.

Characteristics of proteolytic microorganisms and their effects on proteolysis in total mixed ration silages of soybean curd residue

Objective

The objective of this study was to isolate proteolytic microorganisms and evaluate their effects on proteolysis in total mixed ration (TMR) silages of soybean curd residue.

Methods

TMRs were formulated with soybean curd residue, alfalfa or Leymus chinensis hay, corn meal, soybean meal, a vitamin-mineral supplement, and salt in a ratio of 25.0:40.0:30.0:4.0:0.5:0.5, respectively, on a basis of dry matter (DM). The microbial proteinases during ensiling were characterized, the dominate strains associated with proteolysis were identified, and their enzymatic characterization were evaluated in alfalfa (A-TMR) and Leymus chinensis (L-TMR) TMR silages containing soybean curd residue.

Results

Both A-TMR and L-TMR silages were well preserved, with low pH and high lactic acid concentrations. The aerobic bacteria and yeast counts in both TMR silages decreased to about 105 cfu g-1 FM (Fresh matter) and below the detection limit, respectively. The lactic acid bacteria count increased to 109 cfu g-1 FM. The total microbial proteinases activities reached their maximums during the early ensiling stage and then reduced in both TMR silages with fermentation prolonged. Metalloproteinase was the main proteinase when the total proteinases activities reached their maximums, and when ensiling terminated, metallo and serine proteinases played equally important parts in proteolysis in both TMR silages. Strains in the genera Curtobacterium and Paenibacillus were identified as the most dominant proteolytic bacteria in A-TMR and L-TMR, respectively, and both their proteinases were mainly with metalloproteinase characteristics. In the latter ensiling phase, Enterococcus faecium strains became the major sources of proteolytic enzymes in both TMR silages. Their proteinases were mainly of metallo and serine proteinases classes in this experiment.

Conclusion

Proteolytic aerobic bacteria were substituted by proteolytic lactic acid bacteria during ensiling, and the microbial serine and metallo proteinases in these strains played leading roles in proteolysis in TMR silages.

Alkaline and Halophilic Protease Production by Bacillus luteus H11 and Its Potential Industrial Applications

This paper presents the results of the study on the production of protease by Bacillus luteus H11 isolated from an alkaline soda lime. B. luteus H11 was identified as an alkalohalophilic bacterium, and its extracellular serine endoprotease also showed an extreme alkali- and halotolerance. It was remarkably stable in the presence of NaCl up to 5 M. The enzyme was active in a broad range of pH values and temperatures, with an optimum pH of 10.5 and a temperature of 45 °C. It had a molecular mass of about 37 kDa and showed activity against azocasein and a synthetic substrate for the subtilisin-like protease, N-succinyl-l-phenylalanine-p-nitroanilide. The halo-alkaline protease produced by B. luteus H11 seems to be significant from an industrial perspective because of its tolerance towards high salinity and alkalinity as well as its stability against some organic solvents, surfactants and oxidants. These properties make the protease suitable for applications in food, detergent and pharmaceutical industries, and also in environmental bioremediation.

Plant growth promotion and suppression of bacterial leaf blight in rice by Paenibacillus polymyxa Sx3

The effects and mechanisms of Paenibacillus polymyxa Sx3 on growth promotion and the suppression of bacterial leaf blight in rice were evaluated in this study. The results from a plate assay indicated that Sx3 inhibited the growth of 20 strains of Xanthomonas oryzae pv. oryzae (Xoo). Rice seedling experiments indicated that Sx3 promoted plant growth and suppressed bacterial leaf blight. In addition, bacteriological tests showed that Sx3 was able to fix nitrogen, solubilize phosphate and produce indole acetic acid, indicating that various mechanisms may be involved in the growth promotion by Sx3. The culture filtrate of P. polymyxa Sx3 reduced bacterial growth, biofilm formation and disrupted the cell morphology of Xoo strain GZ 0005, as indicated by the transmission and scanning electron microscopic observations. In addition, MALDI-TOF MS analysis revealed that Sx3 could biosynthesize two types of secondary metabolites fusaricidins and polymyxin P. In summary, this study clearly indicated that P. polymyxa Sx3 has strong in vitro and in vivo antagonistic activity against Xoo, which may be at least partially attributed to its production of secondary metabolites. SIGNIFICANCE AND IMPACT OF THE STUDY: Antagonistic bacteria can grow well in their originating environment. However, it is unclear whether antagonistic bacteria were able to survive in different ecological environments. This study revealed that Paenibacillus polymyxa Sx3 isolated from rhizosphere soil of cotton significantly promoted the plant growth and suppressed bacterial leaf blight in rice. Therefore, it could be inferred that P. polymyxa Sx3 has the potential to be used as biocontrol agents in plants grown in different ecological environments.

Recovery of phosphorus and volatile fatty acids from wastewater and food waste with an iron-flocculation sequencing batch reactor and acidogenic co-fermentation

A sequencing batch reactor-based system was developed for enhanced phosphorus (P) removal and recovery from municipal wastewater. The system consists of an iron-dosing SBR for P precipitation and a side-stream anaerobic reactor for sludge co-fermentation with food waste. During co-fermentation, sludge and food waste undergo acidogenesis, releasing phosphates under acidic conditions and producing volatile fatty acids (VFAs) into the supernatant. A few types of typical food waste were investigated for their effectiveness in acidogenesis and related enzymatic activities. The results show that approximately 96.4% of total P in wastewater was retained in activated sludge. Food waste with a high starch content favoured acidogenic fermentation. Around 55.7% of P from wastewater was recovered as vivianite, and around 66% of food waste loading was converted into VFAs. The new integration formed an effective system for wastewater treatment, food waste processing and simultaneous recovery of P and VFAs.

Production, purification, and characterization of metalloprotease from Candida kefyr 41 PSB

A thermostable metalloprotease, produced from an environmental strain of Candida kefyr 41 PSB, was purified 16 fold with a 60% yield by cold ethanol precipitation and affinity chromatography (bentonite-acrylamide-cysteine microcomposite). The purified enzyme appeared as a single protein band at 43kDa. Its optimum pH and temperature points were found to be 7.0 and 105°C, respectively. K_m and V_max values of the enzyme were determined to be 3.5mg/mL and 4.4μmolmL^-1min^-1, 1.65mg/mL and 6.1μmolmL^-1min^-1, using casein and gelatine as the substrates, respectively. The activity was inhibited by using ethylenediamine tetraacetic acid (EDTA), indicating that the enzyme was a metalloprotease. Stability of the enzyme was investigated by using thermodynamic and kinetic parameters. The thermal inactivation profile of the enzyme conformed to the first order kinetics. The half life of the enzyme at 95, 105, 115, 125 and 135°C was 1310, 610, 220, 150, and 86min, respectively.

Biological Control of Apple Anthracnose by Paenibacillus polymyxa APEC128, an Antagonistic Rhizobacterium

The present study investigated the suppression of the disease development of anthracnose caused by Colletotrichum gloeosporioides and C. acutatum in harvested apples using an antagonistic rhizobacterium Paenibacillus polymyxa APEC128 (APEC128). Out of 30 bacterial isolates from apple rhizosphere screened for antagonistic activity, the most effective strain was APEC128 as inferred from the size of the inhibition zone. This strain showed a greater growth in brain-heart infusion (BHI) broth compared to other growth media. There was a reduction in anthracnose symptoms caused by the two fungal pathogens in harvested apples after their treatment with APEC128 in comparison with non-treated control. This effect is explained by the increased production of protease and amylase by APEC128, which might have inhibited mycelial growth. In apples treated with different APEC128 suspensions, the disease caused by C. gloeosporioides and C. acutatum was greatly suppressed (by 83.6% and 79%, respectively) in treatments with the concentration of 1 × 10(8) colony forming units (cfu)/ml compared to other lower dosages, suggesting that the suppression of anthracnose development on harvested apples is dose-dependent. These results indicated that APEC128 is one of the promising agents in the biocontrol of apple anthracnose, which might help to increase the shelf-life of apple fruit during the post-harvest period.

Purification and characterization of an extracellular haloalkaline serine protease from the moderately halophilic bacterium, Bacillus iranensis (X5B)

This study reports the purification and characterization of an extracellular haloalkaline serine protease from the moderately halophilic bacterium, Bacillus iranensis, strain X5B. The enzyme was purified to homogeneity by acetone precipitation, ultrafiltration and carboxymethyl (CM) cation exchange chromatography, respectively. The purified protease was a monomeric enzyme with a relative molecular mass of 48-50 kDa and it was inhibited by PMSF indicating that it is a serine-protease. The optimum pH, temperature and NaCl concentration were 9.5, 35 °C and 0.98 M, respectively. The enzyme showed a significant tolerance to salt and alkaline pH. It retained approximately 50% of activity at 2.5 M NaCl and about 70% of activity at highly alkaline pH of 11.0; therefore, it was a moderately halophilic and also can be activated by metals, especially by Ca(2+). The specific activity of the purified protease was measured to be 425.23 μmol of tyrosine/min per mg of protein using casein as a substrate. The apparent K m and V max values were 0.126 mM and 0.523 mM/min, respectively and the accurate value of k cat was obtained as 3.284 × 10(-2) s(-1). These special and important characteristics make this serine protease as valuable tool for industrial applications.

High Milk-Clotting Activity Expressed by the Newly Isolated Paenibacillus spp. Strain BD3526

Paenibacillus spp. BD3526, a bacterium exhibiting a protein hydrolysis circle surrounded with an obvious precipitation zone on skim milk agar, was isolated from raw yak (Bos grunniens) milk collected in Tibet, China. Phylogenetic analysis based on 16S rRNA and whole genome sequence comparison indicated the isolate belong to the genus Paenibacillus. The strain BD3526 demonstrated strong ability to produce protease with milk clotting activity (MCA) in wheat bran broth. The protease with MCA was predominantly accumulated during the late-exponential phase of growth. The proteolytic activity (PA) of the BD3526 protease was 1.33-fold higher than that of the commercial R. miehei coagulant. A maximum MCA (6470 ± 281 SU mL⁻¹) of the strain BD3526 was reached under optimal cultivation conditions. The protease with MCA was precipitated from the cultivated supernatant of wheat bran broth with ammonium sulfate and purified by anion-exchange chromatography. The molecular weight of the protease with MCA was determined as 35 kDa by sodium dodecyl sulfate-polyacrylamide gels electrophoresis (SDS-PAGE) and gelatin zymography. The cleavage site of the BD3526 protease with MCA in κ-casein was located at the Met₁₀₆–Ala₁₀₇ bond, as determined by mass spectrometry analysis.

Enzymes produced by halotolerant spore-forming gram-positive bacterial strains isolated from a resting habitat (Restinga de Jurubatiba) in Rio de Janeiro, Brazil: focus on proteases

The screening for hydrolases-producing, halotolerant, and spore-forming gram-positive bacteria from the root, rhizosphere, and non-rhizosphere soil of Blutaparon portulacoides, a plant found in the Restinga de Jurubatiba located at the northern region of Rio de Janeiro State, Brazil, resulted in the isolation of 22 strains. These strains were identified as Halobacillus blutaparonensis (n = 2), Oceanobacillus picturae (n = 5), and Oceanobacillus iheyensis (n = 15), and all showed the ability to produce different extracellular enzymes. A total of 20 isolates (90.9 %) showed activity for protease, 5 (22.7 %) for phytase, 3 (13.6 %) for cellulase, and 2 (9.1 %) for amylase. Some bacterial strains were capable of producing three (13.6 %) or two (9.1 %) distinct hydrolytic enzymes. However, no bacterial strain with ability to produce esterase and DNase was observed. The isolate designated M9, belonging to the species H. blutaparonensis, was the best producer of protease and also yielded amylase and phytase. This strain was chosen for further studies regarding its protease activity. The M9 strain produced similar amounts of protease when grown either without or with different NaCl concentrations (from 0.5 to 10 %). A simple inspection of the cell-free culture supernatant by gelatin-sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed the presence of three major alkaline proteases of 40, 50, and 70 kDa, which were fully inhibited by phenylmethylsulfonyl fluoride (PMSF) and tosyl-L-phenylalanine chloromethyl ketone (TPCK) (two classical serine protease inhibitors). The secreted proteases were detected in a wide range of temperature (from 4 to 45 °C) and their hydrolytic activities were stimulated by NaCl (up to 10 %). The serine proteases produced by the M9 strain cleaved gelatin, casein, albumin, and hemoglobin, however, in different extensions. Collectively, these results suggest the potential use of the M9 strain in biotechnological and/or industrial processes.

Isolation of Paenibacillus pinesoli sp. nov. from forest soil in Gyeonggi-Do, Korea

Using a new culture method for unculturable soil bacteria, strain NB5(T) was isolated from forest soil at Kyonggi University, and characterized taxonomically on the basis of 16S rRNA gene sequence as well as phenotypic and chemotaxonomic characteristics. The novel strain was a Gram- and catalase-positive, rod-shaped bacterium, which grew in the pH range 6.0-9.5 (optimum, 6.5-9.5) and at temperatures between 15°C and 45°C (optimum, 25-40°C). Growth was possible at 0-5% NaCl (optimum, 0% to 3%) in nutrient, Luria-Bertani, and trypticase soy broths (TSB), as well as R2A medium (with optimal growth in TSB). A phylogenetic analysis of the 16S rRNA gene sequence showed that the novel strain was affiliated with the genus Paenibacillus and had 96.8% and 96.5% similarity to P. nanensis MX2-3(T) and P. agaridevorans DSM 1355(T), respectively. The predominant menaquinone in NB5(T) was MK-7; the major fatty acids were anteiso-C15:0 and iso-C16:0; and the DNA G+C content was 54.5 mol%. We propose this strain as a novel species of the genus Paenibacillus, and suggest the name Paenibacillus pinesoli sp. nov. (type strain, KACC 17472(T)=KEMB 9005-025(T)=JCM 19203(T)).

Extracellular proteases of Halobacillus blutaparonensis strain M9, a new moderately halophilic bacterium

Halophilic microorganisms are source of potential hydrolytic enzymes to be used in industrial and/or biotechnological processes. In the present study, we have investigated the ability of the moderately halophilic bacterium Halobacillus blutaparonensis (strain M9), a novel species described by our group, to release proteolytic enzymes. This bacterial strain abundantly proliferated in Luria-Bertani broth supplemented with 2.5% NaCl as well as secreted proteases to the extracellular environment. The production of proteases occurred in bacterial cells grown under different concentration of salt, ranging from 0.5% to 10% NaCl, in a similar way. The proteases secreted by H. blutaparonensis presented the following properties: (i) molecular masses ranging from 30 to 80 kDa, (ii) better hydrolytic activities under neutral-alkaline pH range, (iii) expression modulated according to the culture age, (iv) susceptibility to phenylmethylsulphonyl fluoride, classifying them as serine-type proteases, (v) specific cleavage over the chymotrypsin substrate, and (vi) enzymatic stability in the presence of salt (up to 20% NaCl) and organic solvents (e.g., ether, isooctane and cyclohexane). The proteases described herein are promising for industrial practices due to its haloalkaline properties.

Draft genome sequence of Paenibacillus peoriae strain KCTC 3763T

Paenibacillus peoriae is a potentially plant-beneficial soil bacterium and is a close relative to Paenibacillus polymyxa, the type species of the genus Paenibacillus. Herein, we present the 5.77-Mb draft genome sequence of the P. peoriae type strain with the aim of providing insight into the genomic basis of plant growth-promoting Paenibacillus species.

Detection and quantification of Paenibacillus polymyxa in the rhizosphere of wild barley (Hordeum spontaneum) with real-time PCR

AIM

To detect and quantify the plant drought tolerance enhancing bacterium Paenibacillus polymyxa in a collection of 160 Hordeum spontaneum rhizosphere samples at the 'Evolution Canyon' ('EC'), Israel.

METHODS AND RESULTS

PCR primers and a FAM-TAMRA probe (6-carboxyfluorescein, 6-carboxy-tetramethyl-rhodamine) targeting 16S rRNA genes were designed and used to detect and quantify the target strain. Two commercial kits, Bio101 Fast Spin and Mo Bio Ultra Clean Soil DNA, were tested for DNA isolation from the rhizosphere and surrounding soil. Population densities of P. polymyxa were studied in the rhizosphere of wild barley and surrounding soil from the contrasting climatic slopes at the 'EC' using the real-time PCR and culture based methods.

CONCLUSION

Paenibacillus polymyxa is one of the best established species in wild barley rhizosphere at the 'EC' slopes. With the real-time PCR assay we are able to detect 1 pg of DNA per PCR corresponding to 100 cells per ml. The results at the 'EC' correlate well to bacterial estimations by culture based methods.

SIGNIFICANCE AND IMPACT OF THE STUDY

Significantly higher P. polymyxa cell number was detected in the rhizosphere of arid 'African' microclimate indicating possible role of adaptive co-evolution with plants.

Ecology and biotechnological potential of Paenibacillus polymyxa: a minireview

Microbial diversity is a major resource for biotechnological products and processes. Bacteria are the most dominant group of this diversity which produce a wide range of products of industrial significance. Paenibacillus polymyxa (formerly Bacillus polymyxa), a non pathogenic and endospore-forming Bacillus, is one of the most industrially significant facultative anaerobic bacterium. It occurs naturally in soil, rhizosphere and roots of crop plants and in marine sediments. During the last two decades, there has been a growing interest for their ecological and biotechnological importance, despite their limited genomic information. P. polymyxa has a wide range of properties, including nitrogen fixation, plant growth promotion, soil phosphorus solubilisation and production of exopolysaccharides, hydrolytic enzymes, antibiotics, cytokinin. It also helps in bioflocculation and in the enhancement of soil porosity. In addition, it is known to produce optically active 2,3-butanediol (BDL), a potentially valuable chemical compound from a variety of carbohydrates. The present review article aims to provide an overview of the various roles that these microorganisms play in the environment and their biotechnological potential.