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

Purification, characterization, optimization, and docking simulation of alkaline protease produced by Brevibacillus agri SAR25 using fish wastes as a substrate

Recycling of protein-rich environmental wastes and obtaining more valuable products from these recycled products is a topic of interest for researchers. This study aims to produce, purify, and characterize the physicochemical and structural properties of the protease enzyme produced from Brevibacillus agri SAR25 using salmon fish waste as substrate and also to evaluate the effect of protease on the chicken feather, enzyme-ligand interactions, and active site surface area. The production of protease was optimum on 50 g/L fish waste, pH 8, 40 °C, 96 h, and 150 rpm. The alkaline protease was isolated using three-phase partitioning (TPP), a straightforward and efficient one-step method for purifying enzymes in industrial applications. TPP achieved a purification efficiency of 115 % with a 3.1-fold increase in concentration. As a result, the molecular weight of the purified protease was determined to be 50 kDa under optimal conditions of pH 9 and 45 °C. The 3D structure of the alkaline protease enzyme with the determined ligands was predicted by homology modeling using UCSF Chimera 1.17.3 software. Tween-20 ligand showed the best binding affinity by hydrogen bonding with amino acids 106 A, Asn 133 A, Gly 198, Asn 226, Glu 232 and hydrophobic interaction with His 135, Leu 283 in the active site of the alkaline protease enzyme, thus leading to the discovery of new semisynthetic enzymes of salmon fish waste. The activity and stability of Brevibacillus agri SAR25 alkaline protease over a wide range of temperatures and pH, and its relatively high stability in the presence of various metal ions, organic solvents, and surfactants indicate that it can be used as a biocatalyst for different industrial applications. This could lead to the creation of new enzymes made from recycled biological materials.

A novel alkali and thermotolerant protease from Aeromonas spp. retrieved from wastewater

Enzymes are integral to numerous industrial processes, with a growing global demand for various enzyme types. Protease enzymes, in particular, have proven to be cost-effective, stable, and compatible alternatives to traditional chemical processes in both industrial and environmental applications. In this study, an alkaline protease-producing strain of Aeromonas spp. was isolated from a wastewater treatment plant in Iran. The protease production was confirmed by culturing the strain on casein agar medium. The bacterium was identified through morphological, biochemical, and 16 S rRNA sequencing analyses. The optimal culture medium for bacterial growth and enzyme production was obtained using peptone, salt, yeast extract, galactose, and CaCl₂ at an initial pH of 8. Maximum protease production was achieved after 20 h of incubation at 40 °C. To partially purify the enzyme, the supernatant of the bacterial culture medium was first centrifuged, and the enzyme was precipitated using ammonium sulfate, followed by dialysis. Zymography revealed the production of one type of protease during bacterial growth. The partially purified protease exhibited optimal activity at pH 8.5 and maximum stability at pH 9. The optimum temperature for maximum enzyme activity was observed at 50 °C, with 100% residual activity retained for 1 h at 0 °C. The effect of metal ions on enzyme activity was assessed, revealing that KCl induced the most significant effects (p < 0.0001) on enzyme activity. Chemical amino acid modifiers and inhibitors, such as EDTA, DEPSI, and IAA, did not exhibit significant inhibition. In contrast, PMSF and HNBB significantly (p < 0.0001) reduced enzyme activity, suggesting that the enzyme could be classified as a serine protease. The protease also demonstrated high stability in the presence of 2% SDS, showing no signs inactivation. The alkaline pH optimum, thermal stability, and resistance to SDS exhibited by the protease produced by the Aeromonas strain are particularly promising characteristics that warrant further investigation. Based on preliminary tests and the enzyme's characteristics, this protease can be recommended for various applications, pending further studies.

Tapping into haloalkaliphilic bacteria for sustainable agriculture in treated wastewater: insights into genomic fitness and environmental adaptation

The increasing salinity and alkalinity of soils pose a global challenge, particularly in arid regions such as Tunisia, where about 50% of lands are sensitive to soil salinization. Anthropogenic activities, including the use of treated wastewater (TWW) for irrigation, exacerbate these issues. Haloalkaliphilic bacteria, adapted to TWW conditions and exhibiting plant-growth promotion (PGP) and biocontrol traits, could offer solutions. In this study, 24 haloalkaliphilic bacterial strains were isolated from rhizosphere sample of olive tree irrigated with TWW for more than 20 years. The bacterial identification using 16S rRNA gene sequencing showed that the haloalkaliphilic isolates, capable of thriving in high salinity and alkaline pH, were primarily affiliated to Bacillota (Oceanobacillus and Staphylococcus). Notably, these strains exhibited biofertilization and enzyme production under both normal and saline conditions. Traits such as phosphate solubilization, and the production of exopolysaccharide, siderophore, ammonia, and hydrogen cyanide were observed. The strains also demonstrated enzymatic activities, including protease, amylase, and esterase. Four selected haloalkaliphilic PGPR strains displayed antifungal activity against Alternaria terricola, with three showing tolerances to heavy metals and pesticides. The strain Oceanobacillus picturea M4W.A2 was selected for genome sequencing. Phylogenomic analyses indicated that the extreme environmental conditions probably influenced the development of specific adaptations in M4W.A2 strain, differentiating it from other Oceanobacillus picturae strains. The presence of the key genes associated with plant growth promotion, osmotic and oxidative stress tolerance, antibiotic and heavy metals resistance hinted the functional capabilities might help the strain M4W.A2 to thrive in TWW-irrigated soils. By demonstrating this connection, we aim to improve our understanding of genomic fitness to stressed environments. Moreover, the identification of gene duplication and horizontal gene transfer events through mobile genetic elements allow the comprehension of these adaptation dynamics. This study reveals that haloalkaliphilc bacteria from TWW-irrigated rhizosphere exhibit plant-growth promotion and biocontrol traits, with genomic adaptations enabling their survival in high salinity and alkaline conditions, offering potential solutions for soil salinization issues.

Molecular basis for the increased activity of ZMS-2 serine protease in the presence of metal ions and hydrogen peroxide

Serine proteases are important enzymes widely used in commercial products and industry. Recently, we identified a new serine protease from the desert bacterium Bacillus subtilis ZMS-2 that showed enhanced activity in the presence of Zn2+, Ag+, or H2O2. However, the molecular basis underlying this interesting property is unknown. Here, we report comparative studies between the ZMS-2 protease and its homolog, subtilisin E (SubE), from B. subtilis ATCC 6051. In the absence of Zn2+, Ag+, or H2O2, both enzymes showed the same level of proteolytic activity, but in the presence of Zn2+, Ag+, or H2O2, ZMS-2 displayed increased activity by 22%, 8%, and 14%, whereas SubE showed decreased activity by 16%, 12%, and 9%, respectively. In silico studies showed that both proteins have almost identical amino acid sequences and folding structures, except for two amino acids located in the protruding loops of the proteins. ZMS-2 contains Ser236 and Ser268, whereas SubE contains Thr236 and Thr268. Replacing Ser236 or Ser268 in ZMS-2 with threonine resulted in variants whose activities were not enhanced by Zn2+ or Ag+. However, this single mutation did not affect the enhancement by H2O2. This finding may be used as a basis for engineering better proteases for industrial uses.

Screening of Bacillus spp. bacterial endophytes for protease production, and application in feather degradation and bio-detergent additive

Research on proteases and secondary metabolites from endophytes is an area that requires attention from researchers. In this study, proteases from Bacillus sp. strain MHSD16 and Bacillus sp. strain MHSD17 endophytes were characterised, and their potential biotechnological applications were investigated. Optimum protease production was achieved when isolates were grown in media containing (g/L): glucose 10g, casein 5g, yeast extract 5g, KH2PO4 2g, Na2CO3 10g at pH 9. The crude protease extracts were active in alkaline environments, thus referred to as alkaline proteases with optimal pH of 10. Additionally, Bacillus sp. strain MHSD 16 and Bacillus sp. strain MHSD17 proteases were active at high temperatures, with optimum enzyme activity at 50 °C. Thermostability profiles of these proteases showed that the enzymes were highly stable between (40-60 °C), maintaining over 85 % stability after 120 min incubation at 60 °C. Furthermore, the enzymes were stable and compatible with various household and laundry detergents. In the presence of commercial laundry detergent, OMO® 68 % and 72 % activity was retained for Bacillus sp. strain MHSD16 and Bacillus sp. strain MHSD17, respectively, while 67 % and 68 % activity were retained in the presence of Sunlight®. The potential application for use in detergents was investigated through the removal of blood stains with the crude alkaline extracts displaying efficient stain removal abilities. Feather degradation was also investigated and Bacillus sp. MHSD17 exhibited feather keratin degrading properties more effectively than Bacillus sp. MHSD16.

Microbial-derived salt-tolerant proteases and their applications in high-salt traditional soybean fermented foods: a review

Different microorganisms can produce different proteases, which can adapt to different industrial requirements such as pH, temperature, and pressure. Salt-tolerant proteases (STPs) from microorganisms exhibit higher salt tolerance, wider adaptability, and more efficient catalytic ability under extreme conditions compared to conventional proteases. These unique enzymes hold great promise for applications in various industries including food, medicine, environmental protection, agriculture, detergents, dyes, and others. Scientific studies on microbial-derived STPs have been widely reported, but there has been little systematic review of microbial-derived STPs and their application in high-salt conventional soybean fermentable foods. This review presents the STP-producing microbial species and their selection methods, and summarizes and analyzes the salt tolerance mechanisms of the microorganisms. It also outlines various techniques for the isolation and purification of STPs from microorganisms and discusses the salt tolerance mechanisms of STPs. Furthermore, this review demonstrates the contribution of modern biotechnology in the screening of novel microbial-derived STPs and their improvement in salt tolerance. It highlights the potential applications and commercial value of salt-tolerant microorganisms and STPs in high-salt traditional soy fermented foods. The review ends with concluding remarks on the challenges and future directions for microbial-derived STPs. This review provides valuable insights into the separation, purification, performance enhancement, and application of microbial-derived STPs in traditional fermented foods.

Optimization of subtilisin production from Bacillus subtilis strain ZK3 and biological and molecular characterization of synthesized subtilisin capped nanoparticles

The increase and dissemination of multi-drug resistant bacteria have presented a major healthcare challenge, making bacterial infections a significant concern. The present research contributes towards the production of bioactive subtilisin from a marine soil isolate Bacillus subtilis strain ZK3. Custard apple seed powder (raw carbon) and mustard oil cake (raw nitrogen) sources showed a pronounced effect on subtilisin production. A 7.67-fold enhancement in the production was evidenced after optimization with central composite design-response surface methodology. Subtilisin capped silver (AgNP) and zinc oxide (ZnONP) nanoparticles were synthesized and characterized by UV-Visible spectroscopy. Subtilisin and its respective nanoparticles revealed significant biological properties such as, antibacterial activity against all tested pathogenic strains with potential against Escherichia coli and Pseudomonas aeruginosa. Prospective antioxidant behavior of subtilisin, AgNP and ZnONP was evidenced through radical scavenging assays with ABTS and DPPH. Subtilisin, AgNP and ZnONP revealed cytotoxic effect against cancerous breast cell lines MCF-7 with IC50of 83.48, 3.62 and 7.57 µg/mL respectively. Characterizations of nanoparticles were carried out by Fourier transform infrared spectroscopy, scanning electron microscopy with energy dispersive X-ray, X-ray diffraction, thermogravimetric analysis and atomic force microscopy analysis to elucidate the structure, surface and thermostability properties. The study proposes the potential therapeutic applications of subtilisin and its nanoparticles, a way forward for further exploration in the field of healthcare.

Characterization of alkaline metalloprotease isolated from halophilic bacterium Bacillus cereus and its applications in various industrial processes

Microbial proteases are one of the most demanding enzymes for various industries with diverse applications in food, pharmaceutics, and textile industries to name the few. An extracellular alkaline metalloprotease was produced and purified from moderate halophilic bacterial strain, Bacillus cereus TS2, with some unique characteristics required for various industrial applications. The protease was produced in basal medium supplemented with casein and was partially purified by ion exchange chromatography followed by ammonium sulphate precipitation. The alkaline metalloprotease has molecular weight of 35 kDa with specific activity of 535.4 µM/min/mg. It can work at wide range of pH from 3 to 12, while showing optimum activity at pH 10. Similarly, the alkaline metalloprotease is stable till the temperature of 80 °C and works at wide range of temperature from 20 to 90 °C with optimum activity at 60 °C. The turnover rate increases in the presence of NaCl and Co+2 with k cat/KM of 1.42 × 103 and 1.27 × 103 s-1.M-1 respectively, while without NaCl and Co+2 it has a value of 7.58× 102. The alkaline metalloprotease was relatively resistant to thermal and solvent mediated denaturation. Applications revealed that the metalloprotease was efficient to remove hair from goat skin, remove blood stains and degrade milk, thus can be a potential candidate for leather, detergent, and food industry.

Optimization, partial purification, and characterization of a novel high molecular weight alkaline protease produced by Halobacillus sp. HAL1 using fish wastes as a substrate

BACKGROUND

Hydrolytic enzymes from halophilic microorganisms have a wide range of industrial applications. Herein, we report the isolation of Halobacillus sp. HAL1, a moderately halophilic bacterium that produces a novel high molecular weight extracellular alkaline protease when grown in fish processing wastes as a substrate.

RESULTS

Results showed that the isolated strain belonged to the genus Halobacillus, and it was designated as Halobacillus sp. HAL1 with the GenBank accession number OK001470. The strain secreted an extracellular alkaline protease, and the highest yield was obtained when it was grown in a medium with fish wastes substrate as the sole nutritional source (10 g/L) and incubated at 25 °C under shaking conditions. The enzyme was partially purified by Sephadex G-100 column chromatography. Zymographic analysis showed two casein degrading bands of about 190 and 250 KDa. The optimum enzyme activity was at a temperature of 50 °C at pH 8. The proteolytic activity was enhanced in the presence of metal ions (Ca²⁺, Mg²⁺, and Mn²⁺), surfactants (Tween 80, SDS, and Triton-X100), H₂O₂, and EDTA.

CONCLUSION

Our study indicates that Haobacillus sp. HAL1 is a moderately halophilic strain and secrets a novel high molecular wight alkaline protease that is suitable for detergent formulation.

DIVERISTY and enzymatic potential of indigenous bacteria from unexplored contaminted soils in Faisalabad

Bacteria residing in contaminated waste soil degrade and utilize organic and inorganic material as a source of nutrients as well as reduce environmental contamination through their enzymatic machinery. This enzymatic potential of indigenous bacteria can be exploited at industrial level through detailed screening, characterization, optimization and purification. In present study, diversity and enzymatic potential of indigenous bacteria was investigated through qualitative and quantitative screening methods from unexplored contaminated soil waste sites in Faisalabad. Shannon diversity (H') index revealed that twenty-eight soil samples from four contaminated sites were highly diverse of amylase, protease and lipase producing bacteria. Maximum protease producing bacteria were detected in fruit waste (1.929 × 10⁷), whereas amylase and lipase producing bacteria were found in industrial (1.475 × 10⁷) and (5.38 × 10⁶), in household waste soil samples. Most of the indigenous bacterial isolates showed potential for multiple enzymes. An isolate OC5 exhibited capability for amylase production and optimization at a wider range of cultural conditions; pH (6-8), temperature (25 °C, 37 °C, 45 °C), incubation time (24-72 h), and NaCl concentrations 0.5-13%, using (1%) starch and lactose as substrates. An isolate OC5 was identified by molecular identification and phylogenetic analysis showed 99% sequence similarity with Bacillus spp. ANOVA was used to analyzed all data statistically. This study enhances the importance of initial screening and reporting of industrially potent indigenous bacteria from unexplored contaminated waste soils. In future, indigenous bacteria in contaminated wastes may be good candidates to solve various environmental pollution problems.

Bacterial Communities Along Environmental Gradients in Tropical Soda Lakes

Soda lake environments are known to be variable and can have distinct differences according to geographical location. In this study, we investigated the effects of different environmental conditions of six adjacent soda lakes in the Pantanal biome (Mato Grosso do Sul state, Brazil) on bacterial communities and their functioning using a metagenomic approach combined with flow cytometry and chemical analyses. Ordination analysis using flow cytometry and water chemistry data from two sampling periods (wet and dry) clustered soda lakes into three different profiles: eutrophic turbid (ET), oligotrophic turbid (OT), and clear vegetated oligotrophic (CVO). Analysis of bacterial community composition and functioning corroborated this ordination; the exception was one ET lake, which was similar to one OT lake during the wet season, indicating drastic shifts between seasons. Microbial abundance and diversity increased during the dry period, along with a considerable number of limnological variables, all indicative of a strong effect of the precipitation-evaporation balance in these systems. Cyanobacteria were associated with high electric conductivity, pH, and nutrient availability, whereas Actinobacteria, Alphaproteobacteria, and Betaproteobacteria were correlated with landscape morphology variability (surface water, surface perimeter, and lake volume) and with lower salinity and pH levels. Stress response metabolism was enhanced in OT and ET lakes and underrepresented in CVO lakes. The microbiome dataset of this study can serve as a baseline for restoring impacted soda lakes. Altogether, the results of this study demonstrate the sensitivity of tropical soda lakes to climate change, as slight changes in hydrological regimes might produce drastic shifts in community diversity.

Screening, characterization, and kinetic studies of a serine alkaline protease from kitchen wastewater bacteria P2S1An and evaluation of its application in nutraceutical production

This present investigation aimed at characterizing the biochemical potential and kinetic study of the protease isolated from kitchen wastewater bacteria, P2S1An. The enzymatic activity was optimum when incubated for 96 h, at 30°C and pH 9.0. The enzymatic activity of the purified protease (PrA) was 10.47-folds that of crude protease (S1). PrA was about 35 kDa in molecular weight. The broad pH and thermal stability, chelators, surfactants and solvent tolerance, and favorable thermodynamics suggested the potentiality of the extracted protease PrA. Thermal activity and stability were enhanced in presence of 1-mM Ca²⁺ ion at high temperatures. The protease was a serine one as its activity was completely diminished in presence of 1-mM PMSF. The V_max , K_m , and K_cat /K_m suggested stability and catalytic efficiency of the protease. PrA hydrolyzes fish protein with 26.61 ± 0.16% of peptide bond cleavage after 240 min, comparable to Alcalase 2.4L (27.13 ± 0.31%). PRACTITIONER POINTS: A serine alkaline protease PrA was extracted from kitchen wastewater bacteria Bacillus tropicus Y14. Protease PrA showed significant activity and stability in a wide temperature and pH range. Protease showed great stability towards additives like metal ions, solvents, surfactants, polyols, and inhibitors. Kinetic study showed that the protease PrA had a prominent affinity and catalytic efficiency for the substrates. PrA hydrolysed fish proteins into short bioactive peptides which signify its potential in the formation of functional food ingredients.

Marine enzymes: Classification and application in various industries

Oceans are regarded as a plentiful and sustainable source of biological compounds. Enzymes are a group of marine biomaterials that have recently drawn more attention because they are produced in harsh environmental conditions such as high salinity, extensive pH, a wide temperature range, and high pressure. Hence, marine-derived enzymes are capable of exhibiting remarkable properties due to their unique composition. In this review, we overviewed and discussed characteristics of marine enzymes as well as the sources of marine enzymes, ranging from primitive organisms to vertebrates, and presented the importance, advantages, and challenges of using marine enzymes with a summary of their applications in a variety of industries. Current biotechnological advancements need the study of novel marine enzymes that could be applied in a variety of ways. Resources of marine enzyme can benefit greatly for biotechnological applications duo to their biocompatible, ecofriendly and high effectiveness. It is beneficial to use the unique characteristics offered by marine enzymes to either develop new processes and products or improve existing ones. As a result, marine-derived enzymes have promising potential and are an excellent candidate for a variety of biotechnology applications and a future rise in the use of marine enzymes is to be anticipated.

Additive-induced pH determines bacterial community composition and metabolome in traditional mustard seed fermented products

Introduction

Kahudi and Kharoli are unique naturally fermented mustard seed products prepared and consumed in the northeastern region of India. The pre-fermentation processing of mustard seeds (soaking, pan-frying, mixing with alkaline or acidic additives, airtight packaging) renders a stringent fermentation environment. The metabolic activities of fermenting bacterial populations yield a myriad of glucosinolate-derived bioactive components which have not been described earlier.

Methods

This present study employed integrated 16S rRNA amplicon sequencing and LC-MS-based metabolomics to elucidate the bacterial diversity and metabolome of the two fermented mustard seed food products.

Results and Discussion

Univariate and multivariate analyses of metabolomics data revealed differential abundances of a few therapeutically-important metabolites viz., sinapine, indole-3-carbinol, γ-linolenic acid in Kahudi, and metabolites viz., β-sitosterol acetate, 3-butylene glucosinolate, erucic acid in Kharoli. A metagenomic investigation involving the 16S rRNA (V3–V4) amplicon sequencing showed the dominance of Firmicutes (99.1 ± 0.18%) in Kahudi, and Firmicutes (79.6 ± 1.92%) and Proteobacteria (20.37 ± 1.94%) in Kharoli. The most abundant genera were Bacillus (88.7 ± 1.67% in Kahudi; 12.5 ± 1.75% in Kharoli) followed by Lysinibacillus (67.1 ± 2.37% in Kharoli; 10.4 ± 1.74% in Kahudi). Members of both these genera are well known for proteolytic and endospore-forming abilities which could have helped in colonizing and thriving in the stringent fermentation environments.

Contrasted microbial community colonization of a bauxite residue deposit marked by a complex geochemical context

Bauxite residue is the alkaline byproduct generated during alumina extraction and is commonly landfilled in open-air deposits. The growth in global alumina production have raised environmental concerns about these deposits since no large-scale reuses exist to date. Microbial-driven techniques including bioremediation and critical metal bio-recovery are now considered sustainable and cost-effective methods to revalorize bauxite residues. However, the establishment of microbial communities and their active role in these strategies are still poorly understood. We thus determined the geochemical composition of different bauxite residues produced in southern France and explored the development of bacterial and fungal communities using Illumina high-throughput sequencing. Physicochemical parameters were influenced differently by the deposit age and the bauxite origin. Taxonomical analysis revealed an early-stage microbial community dominated by haloalkaliphilic microorganisms and strongly influenced by chemical gradients. Microbial richness, diversity and network complexity increased significantly with the deposit age, reaching an equilibrium community composition similar to typical soils after decades of natural weathering. Our results suggested that salinity, pH, and toxic metals affected the bacterial community structure, while fungal community composition showed no clear correlations with chemical variations.

Production of subtilisin proteases in bacteria and yeast

In this review, we discuss the progress in the study and modification of subtilisin proteases. Despite longstanding applications of microbial proteases and a large number of research papers, the search for new protease genes, the construction of producer strains, and the development of methods for their practical application are still relevant and important, judging by the number of citations of the research articles on proteases and their microbial producers. This enzyme class represents the largest share of the industrial production of proteins worldwide. This situation can explain the high level of interest in these enzymes and points to the high importance of designing domestic technologies for their manufacture. The review covers subtilisin classification, the history of their discovery, and subsequent research on the optimization of their properties. An overview of the classes of subtilisin proteases and related enzymes is provided too. There is a discussion about the problems with the search for (and selection of) subtilases from natural strains of various microorganisms, approaches to (and specifics of) their modification, as well as the relevant genetic engineering techniques. Details are provided on the methods for expression optimization of industrial subtilases of various strains: the details of the most important parameters of cultivation, i.e., composition of the media, culture duration, and the influence of temperature and pH. Also presented are the results of the latest studies on cultivation techniques: submerged and solid-state fermentation. From the literature data reviewed, we can conclude that native enzymes (i.e., those obtained from natural sources) currently hardly have any practical applications because of the decisive advantages of the enzymes modified by genetic engineering and having better properties: e.g., thermal stability, general resistance to detergents and specific resistance to various oxidants, high activity in various temperature ranges, independence from metal ions, and stability in the absence of calcium. The vast majority of subtilisin proteases are expressed in producer strains belonging to different species of the genus Bacillus. Meanwhile, there is an effort to adapt the expression of these enzymes to other microbes, in particular species of the yeast Pichia pastoris.

Improvement of the halotolerance of a Bacillus serine protease by protein surface engineering

A moderately halotolerant serine protease was previously isolated from Bacillus subtilis from salted, fermented food. Eight mutation sites on the protein surface were selected for protein engineering based on sequence and structural comparisons with moderately halotolerant proteases and homologous non-halotolerant proteases. The newly constructed multiple mutants with substituted Asp and Arg residues were compared with the recombinant wild type (rApr) and the previously constructed mAla-8 substituted with Ala to analyze the contribution of protein surface charge to the salt adaptation of the protease. The three mutants showed >1.2-fold greater halotolerance than rApr. In addition, the mutants showed a broader range of pH stability than rApr, retaining >80% of their maximum activity in the pH range 5.0-11. The mutants also retained >75% of their activity after incubation for 1 h at pH 8.0 and 55°C or at pH 11.5 and 25°C. The Asp and Arg residues exchanged by multiple substitution probably played a role in increasing protein surface hydration and solubility in high salt conditions. This study illustrated that increasing a high proportion of the negative or positive charge on the surface of the Bacillus serine protease stably improved the protein's salt adaptation.

PROFICS: A bacterial selection system for directed evolution of proteases

Proteases serve as important tools in biotechnology and as valuable drugs or drug targets. Efficient protein engineering methods to study and modulate protease properties are thus of great interest for a plethora of applications. We established PROFICS (PRotease Optimization via Fusion-Inhibited Carbamoyltransferase-based Selection), a bacterial selection system, which enables the optimization of proteases for biotechnology, therapeutics or diagnosis in a simple overnight process. During the PROFICS process, proteases are selected for their ability to specifically cut a tag from a reporter enzyme and leave a native N-terminus. Precise and efficient cleavage after the recognition sequence reverses the phenotype of an Escherichia coli knockout strain deficient in an essential enzyme of pyrimidine synthesis. A toolbox was generated to select for proteases with different preferences for P1' residues (the residue immediately following the cleavage site). The functionality of PROFICS is demonstrated with viral proteases and human caspase-2. PROFICS improved caspase-2 activity up to 25-fold after only one round of mutation and selection. Additionally, we found a significantly improved tolerance for all P1' residues caused by a mutation in a substrate interaction site. We showed that this improved activity enables cells containing the new variant to outgrow cells containing all other mutants, facilitating its straightforward selection. Apart from optimizing enzymatic activity and P1' tolerance, PROFICS can be used to reprogram specificities, erase off-target activity, optimize expression via tags/codon usage, or even to screen for potential drug-resistance-conferring mutations in therapeutic targets such as viral proteases in an unbiased manner.

Microbial communities of soda lakes and pans in the Carpathian Basin: a review

In this review, I would like to summarize the current knowledge on the microbiology of soda lakes and pans of the Carpathian Basin. First, the characteristic physical and chemical features of these sites are described. Most of the microbiological information presented deals with prokaryotes and algae, but protists and viruses are also mentioned. Planktonic bacterial communities are dominated by members of the phyla Actinobacteria, Bacteroidetes and Proteobacteria; small-sized trebouxiophycean green algae and Synechococcus/Cyanobium picocyanobacteria are the most important components of phytoplankton. Based on the current knowledge, it seems that mainly temperature, salinity, turbidity and grazing pressure regulate community composition and the abundance of individual microbial groups, but the external nutrient load from birds also has a significant impact on the ecological processes.

Genome sequencing of cold-adapted Planococcus bacterium isolated from traditional shrimp paste and protease identification

BACKGROUND

Psychrophiles have evolved to adapt to freezing environments, and cold-adapted enzymes from these organisms can maintain high catalytic activity at low temperature. The use of cold-adapted enzymes has great potential for the revolution of food and molecular biology industries.

RESULTS

In this study, four different strains producing protease were isolated from traditional fermented shrimp paste, one of which, named Planococcus maritimus XJ11 by 16S rRNA nucleotide sequence analysis, exhibited the largest protein hydrolysis clear zone surrounding the colonies. Meanwhile, the strain P. maritimus XJ11 was selected for further investigation because of its great adaptation to low temperature, low salinity and alkaline environment. The enzyme activity assay of P. maritimus XJ11 indicated that the optimum conditions for catalytic activity were pH 10.0 and 40 °C. Moreover, the enzyme also showed an increasing activity with temperatures from 10 to 40 °C and retained more than 67% activity of the maximum over a broad range of salinity (50-150 g L^-1 ). Genome sequencing analysis revealed that strain XJ11 possessed one circular chromosome of 3 282 604 bp and one circular plasmid of 67 339 bp, with a total number of 3293 open reading frames (ORFs). Besides, 21 genes encoding protease, including three serine proteases, were identified through the NR database.

CONCLUSION

Cold-adapted bacterium P. maritimus XJ11 was capable of producing alkaline proteases with high catalytic efficiency at low or moderate temperatures. Furthermore, the favorable psychrophilic and enzymatic characters of strain P. maritimus XJ11 seem to have a promising potential for industrial application. © 2020 Society of Chemical Industry.

Production, properties and some applications of protease from alkaliphilic Bacillus sp. EBTA6

Extracellular protease production by a novel strain, Bacillus sp. EBTA6, has been optimized by using central composite design of response surface methodology and properties and industrial applications of crude enzyme have been investigated. Three independent variables (temperature, pH and yeast extract concentration) chosen in the experimental design were significant terms and reduced cubic model fit with the design at p < 0.0001 level. The recommended temperature, pH and yeast extract concentration were 30 °C, 8, and 15 g/L, respectively. Crude enzyme displayed activity over a wide pH and temperature ranges having the optimum at 50-60 °C and pH 8. It was quite stable at high pH values and at 50 °C. Amongst the metal ions (Mg⁺, Cu²⁺, Ca²⁺, Zn²⁺, K²⁺, and Sn²⁺), Ca²⁺ enhanced the activity and the others either decreased or did not change it. The enzyme activity was reduced by phenyl-methyl-sulfonyl fluoride (PMSF), and ethylene diamine tetra acetic acid (EDTA). The results revealed that the protease was serine alkaline type. Tween 20 and Tween 80 did not inhibit the enzyme, however, sodium dodecyl sulfate (SDS), reduced it by 39%. It completely removed blood stain in 20 min and coagulated milk in the presence of CaCl₂.

Enhanced catalytic activity of Bacillus aryabhattai P1 protease by modulation with nanoactivator

In the developing area of modern nanobiotechnology, the research is being focused on enhancement of catalytic performance in terms of efficiency and stability of enzymes to fulfill the industrial demand. In the context of this interdisciplinary era, we isolated and identified alkaline protease producer Bacillus aryabhattai P1 by polyphasic approach and then followed one variable at a time approach to optimize protease production from P1. The modified components of fermentation medium (g/L) were wheat bran 10, soybean flour 10, yeast extract 5, NaCl 10, KH₂PO₄ 1, K₂HPO₄ 1 and MgSO₄·7H₂O 0.2 (pH 9). The optimum alkaline protease production from P1 was recorded 75 ± 3 U/mg at 35 °C and pH 9 after 96 h of fermentation period. Molecular weight of partially purified P1 alkaline protease was 26 KDa as revealed by SDS-PAGE. Calcium based nanoceramic material was prepared by wet chemical precipitation method and doped in native P1 protease for catalytic activity enhancement. Catalytic activity of modified P1 protease was attained by nanoactivator mediated modulation was more by 5.58 fold at pH 10 and 30 °C temperature. The nanoceramic material named as nanoactivator, with grain size of 40–60 nm was suitable to redesign the active site of P1 protease. Such types of modified proteases can be used in different nanobiotechnological applications.

Effect of Cultural Conditions on Protease Production by a Thermophilic Geobacillus thermoglucosidasius SKF4 Isolated from Sungai Klah Hot Spring Park, Malaysia

Major progress in the fields of agriculture, industry, and biotechnology over the years has influenced the quest for a potent microorganism with favorable properties to be used in scientific research and industry. This study intended to isolate a new thermophilic-protease-producing bacterium and evaluate its growth and protease production under cultural conditions. Protease producing bacteria were successfully isolated from Sungai Klah Hot Spring Park in Perak, Malaysia, and coded as SKF4; they were promising protease producers. Based on microscopic, morphological, and 16S rRNA gene analysis, isolate SKF4 was identified as Geobacillus thermoglucosidasius SKF4. The process of isolating SKF4 to grow and produce proteases under different cultural conditions, including temperature, pH, NaCl concentration, carbon and nitrogen sources, and incubation time, was explored. The optimum cultural conditions observed for growth and protease production were at 60 to 65 °C of temperature, pH 7 to 8, and under 1% NaCl concentration. Further, the use of casein and yeast extract as the nitrogen sources, and sucrose and fructose as the carbon sources enhanced the growth and protease production of isolate SKF4. Meanwhile, isolate SKF4 reached maximum growth and protease production at 24 h of incubation time. The results of this study revealed a new potent strain of thermophilic bacterium isolated from Sungai Klah Hot Spring Park in Perak, Malaysia for the first time. The high production of thermostable protease enzyme by G. thermoglucosidasius SKF4 highlighted the promising properties of this bacterium for industrial and biotechnological applications.