Optimization, purification and characterization of novel thermostable, haloalkaline, solvent stable protease from Bacillus halodurans CAS6 using marine shellfish wastes: a potential additive for detergent and antioxidant synthesis

Proteases, a powerful biochemical tool in the service of medicine, clinical and pharmaceutical

Proteases, enzymes that hydrolyze peptide bonds, have various applications in medicine, clinical applications, and pharmaceutical development. They are used in cancer treatment, wound debridement, contact lens cleaning, prion degradation, biofilm removal, and fibrinolytic agents. Proteases are also crucial in cardiovascular disease treatment, emphasizing the need for safe, affordable, and effective fibrinolytic drugs. Proteolytic enzymes and protease biosensors are increasingly used in diagnostic and therapeutic applications. Advanced technologies, such as nanomaterials-based sensors, are being developed to enhance the sensitivity, specificity, and versatility of protease biosensors. These biosensors are becoming effective tools for disease detection due to their precision and rapidity. They can detect extracellular and intracellular proteases, as well as fluorescence-based methods for real-time and label-free detection of virus-related proteases. The active utilization of proteolytic enzymatic biosensors is expected to expand significantly in biomedical research, in-vitro model systems, and drug development. We focused on journal articles and books published in English between 1982 and 2024 for this study.

Eco-friendly and safe alternatives for the valorization of shrimp farming waste

The seafood industry generates waste, including shells, bones, intestines, and wastewater. The discards are nutrient-rich, containing varying concentrations of carotenoids, proteins, chitin, and other minerals. Thus, it is imperative to subject seafood waste, including shrimp waste (SW), to secondary processing and valorization for demineralization and deproteination to retrieve industrially essential compounds. Although several chemical processes are available for SW processing, most of them are inherently ecotoxic. Bioconversion of SW is cost-effective, ecofriendly, and safe. Microbial fermentation and the action of exogenous enzymes are among the significant SW bioconversion processes that transform seafood waste into valuable products. SW is a potential raw material for agrochemicals, microbial culture media, adsorbents, therapeutics, nutraceuticals, and bio-nanomaterials. This review comprehensively elucidates the valorization approaches of SW, addressing the drawbacks of chemically mediated methods for SW treatments. It is a broad overview of the applications associated with nutrient-rich SW, besides highlighting the role of major shrimp-producing countries in exploring SW to achieve safe, ecofriendly, and efficient bio-products.

Coproduction of alkaline protease and xylanase from genetically modified Indonesian local Bacillus halodurans CM1 using corncob as an inducing substrate

The production of corn generates a substantial amount of agro-industrial waste, with corncob accounting for a significant portion of this waste. In this study, we focused on utilizing corncob as a carbon source and inducer to simultaneously produce two valuable industrial enzymes, protease, and xylanase, using a recombinant strain of B. halodurans CM1. Interestingly, xylan-rich corncob not only enhanced the xylanase activity but also induced protease activity of the modified B. halodurans CM1 strain. The effect of corncob concentration on the coproduction of protease and xylanase was investigated. Corncob with 6 % concentration induced protease activity of 1020.7 U/mL and xylanase activity of 502.8 U/mL in a 7 L bioreactor under the condition of 1 vvm aeration, 250 rpm agitation, 37 °C temperature, initial pH 9.0, and 40 h incubation period. The protease produced was an alkalothermophilic enzyme whose highest activity was at pH 12 and 50 °C, and it belonged to a serine protease family. This alkalothermophilic protease's activity to some degree was reduced by Co2+, Mg2+, Fe2+, Zn2+, and K+, but enhanced by Ca2+ and Ni2+ (at 5 mM). The protease was stable even under the presence of a 15 % concentration of acetone, DMSO, ethanol, and isopropyl alcohol. The protease activity at 30 °C was not considerably changed by the presence of detergent, indicating excellent potential as a washing detergent additive. According to these findings, corncob has the potential to be a substrate for the coproduction of protease and xylanase, which have a wide range of industrial uses.

Transcriptome analysis reveals the underlying mechanism for over-accumulation of alkaline protease in Bacillus licheniformis

AIMS

Bacillus licheniformis AQ is an industrial strain with high production of alkaline protease (AprE), which has great industrial application value. However, how to regulate the production of AprE in the process of industrial fermentation is still not completely clear. Therefore, it is important to understand the metabolic process of AprE production in the industrial fermentation medium.

METHODS AND RESULTS

In this study, transcriptome sequencing of the whole fermentation course was performed to explore the synthesis and regulation mechanism of AprE in B. licheniformis AQ. During the fermentation process, the AprE got continuously accumulated, reaching a peak of 42 020 U/mL at the fermentation endpoint (48 h). Meanwhile, the highly expressed genes were observed. Compared with the fermentation endpoint, there were 61 genes in the intersection of differentially expressed genes, functioning as catabolic processes, peptidases and inhibitors, chaperones, and folding catalysts. Furthermore, the protein-protein interactions network of AprE was constructed.

CONCLUSION

This study provides important transcriptome information for B. licheniformis AQ and potential molecular targets for further improving the production of AprE.

Application of the novel manta-ray foraging algorithm to optimize acidic peptidase production in solid-state fermentation using binary agro-industrial waste

Peptidases, which constitute about 20% of the global enzyme market, have found applications in detergent, food and pharmaceutical industries, and could be produced on a large scale using low-cost agro-industrial waste. An acidophilic Bacillus cereus strain produced acidic peptidase on binary-agro-industrial waste comprising yam peels and fish processing waste at pH 4.5 with high catalytic activity. A five-variable central composite rotatable design of a response surface methodology was used to model bioprocess conditions for improved peptidase production in solid-state fermentation. Data generated was leveraged as the basis for applying the novel Manta-ray foraging optimization-linked feed-forward artificial neural network to predict bioprocess conditions optimally. Results obtained from the optimization experiments revealed a significant coefficient of determination of 0.9885 with low-performance error. The bioprocess predicted a peptidase activity of 1035.32 U/mL under optimized conditions set as 54.8 g/100 g yam peels, 23.85 g/100 g fish waste, 0.31 g/100 g CaCl2, 47.54% (v/w) moisture content, and pH 2. Peptidase activity was improved 5-fold, and was stable for 240 min between pH 2.5 and 3.5. Michaelis-Menten kinetics revealed a Km of 0.119 mM and a catalytic efficiency of 45462.19 mM-1 min-1. The bioprocess holds promise for sustainable enzyme-driven applications.

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.

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.

Complete genome sequence of Bacillus Licheniformis NWMCC0046, a candidate for the laundry industry

In this study, selected properties of protease and the complete genome sequence of Bacillus licheniformis NWMCC0046 were investigated, to discover laundry applications and other potential probiotic properties of this strain. Partial characterization of B. licheniformis NWMCC0046 showed that its protease has good activity both in alkaline environments and at low temperatures. Also, the protease is compatible with commercial detergents and can be used as a detergent additive for effective stain removal at low temperatures. The complete genome sequence of B. licheniformis NWMCC0046 is comprised of a 4,321,565 bp linear chromosome with a G + C content of 46.78% and no plasmids. It had 4504 protein-encoding genes, 81 transfer RNA (tRNA) genes, and 24 ribosomal RNA (rRNA) genes. Genomic analysis revealed genes involved in exocellular enzyme production and probiotic properties. In addition, genomic sequence analysis revealed specific genes encoding carbohydrate metabolism pathways, resistance, and cold adaptation capacity. Overall, protease properties show its potential as a detergent additive enzyme. The complete genome sequence information of B. licheniformis NWMCC0046 was obtained, and functional prediction revealed its numerous probiotic properties.

Overproduction of a thermo-stable halo-alkaline protease on agro-waste-based optimized medium through alternate combinatorial random mutagenesis of Stenotrophomonas acidaminiphila

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Alternate combinatorial random mutagenesis selected a protease high-yielding mutant.

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Medium optimization led to 25.55-fold raise in specific protease yield in bioreactor.

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20% PEG-1500/Na+ 15% citrate recovered 74% activity yield with 52.55 purity.

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Activity was retained at elevated physicochemical levels but inhibited by PMSF.

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Keratinolytic and blood-stain removal activities confer industrial potential on protease.

A strain of Stenotrophomonas acidaminiphila, isolated from fermenting bean-processing wastewater, produced alkaline protease in pretreated cassava waste-stream, but with low yield. Strain improvement by alternate combinatorial random mutagenesis and bioprocess optimization using comparative statistical and neural network methods enhanced yield by 17.8-fold in mutant kGy-04-UV-25. Kinetics of production by selected mutant modeled by logistic and modified Gompertz functions revealed higher specific growth rate in mutant than in the parent strain, likewise volumetric and specific productivities. Purification by PEG/Na⁺ citrate aqueous two-phase system recovered 73.87% yield and 52.55-fold of protease. Its activity was stable at 5–35% NaCl, 45–75°C, and was significantly enhanced by 1–15 mM sodium dodecyl sulfate (SDS). The protease was inhibited by low concentrations of phenyl-methyl-sulfonyl fluoride but was activated by 1–5 mM Mn²⁺ suggesting a manganese-dependent serine‑protease. The 45.7 kDa thermo-halo-stable alkaline protease demonstrated keratinolytic and blood-stain removal potentials showing prospects in textile and detergent industries, respectively.

Characterization of Some Salt-Tolerant Bacterial Hydrolases with Potential Utility in Cultural Heritage Bio-Cleaning

Salt-tolerant enzymes produced by halophilic and halotolerant microorganisms have been proposed to be used in various applications that involve high saline conditions. Considering their biotechnological significance and the current need for more efficient producers of such catalysts, the present study aimed to evaluate the extracellular proteolytic, esterolytic, cellulolytic and xylanolytic activities of some halotolerant strains, and to characterize their functional parameters. A total of 21 bacterial and fungal strains belonging to the genera Bacillus, Virgibacillus, Salinivibrio, Salinicoccus, Psychrobacter, Nocardiopsis, Penicillium, Aspergillus, and Emericellopsis were assayed by quantitative methods. Among them, the members of the Bacillus genus exhibited the highest catalytic activities. The exoenzymes produced by three selected Bacillus strains were active over wide ranges of salinity, temperature and pH. Proteases were active at 20–80 °C, pH 6–10, and 0–1 M NaCl, while esterases showed good catalytic activities at 20–80 °C, pH 7.5–10, and 0–4 M NaCl. Cellulases and xylanases were active at 20–80 °C, pH 5–10, and 0–5 M NaCl. Due to such properties, these hydrolases could be used in a newly proposed application, namely to clean aged consolidants and organic deposits accumulated over time from the surfaces of salt-loaded wall paintings.

A Novel Thermostable and Alkaline Protease Produced from Bacillus stearothermophilus Isolated from Olive Oil Mill Sols Suitable to Industrial Biotechnology

This study was conducted to identify a new alkaline and thermophilic protease (Ba.St.Pr) produced from Bacillus stearothermophilus isolated from olive oil mill sols and to evaluate its culture conditions, including temperature, pH, carbon and nitrogen sources, and incubation time. The optimum culture conditions for cell growth (10 g/L) and protease production (5050 U/mL) were as follows: temperature 55 °C, pH 10, inoculation density 8 × 10⁸ CFU/mL, and incubation time 24 h. The use of 3% yeast extract as the nitrogen sources and galactose (7.5 g/L) as the carbon sources enhanced both cell growth and protease production. Using reversed-phase analytical HPLC on C-8 column, the new protease was purified with a molecular mass of approximately 28 kDa. The N-terminal sequence of Ba.St.Pr exhibited a high level of identity of approximately 95% with those of Bacillus strains. Characterization under extreme conditions revealed a novel thermostable and alkaline protease with a half-life time of 187 min when incubated with combined Ca²⁺/mannitol. Ba.St.Pr demonstrated a higher stability in the presence of surfactant, solvent, and Ca²⁺ ions. Consequently, all the evaluated activity parameters highlighted the promising properties of this bacterium for industrial and biotechnological applications.

Virgibacillus dokdonensis VITP14 produces α-amylase and protease with broader operational range but with differential thermodynamic stability

Extracellular α-amylase and protease were coproduced from halotolerant Virgibacillus dokdonensis VITP14 with banana peels (2% w/v) as substrate. The pH optima for α-amylase and protease were 6.5 and 7.0 respectively. The temperature optima of α-amylase and protease were 30°C and 50°C respectively. Both the enzymes were active in the presence of various metal ions (1 mM of Ni²⁺, Ca²⁺, Ba²⁺, Sr²⁺ and Mg²⁺⁾, detergents (Tween 20, Tween 80, Triton X-100) and other additives (2-mercaptoethanol and urea). Both the enzymes followed Michaelis-Menten type enzyme kinetics with V_max of 121.40 μmol min^-1 ml^-1 and 4.17 μmol min^-1 ml^-1 and K_m of 0.59 mg ml^-1 and 0.28 mg ml^-1 for amylase and protease respectively. Amylase showed higher activation energy for inactivation (75.55 kJ mol^-1 compared to 59.70 kJ mol^-1 for protease) and higher thermal stability (reflected by longer half-life 53.23 min compared to 0.11 min for protease) at 60°C. The coexistence of amylase and protease could be attributed to the difference in the optimum temperatures of activity and thermal stability of the two enzymes. This article is protected by copyright. All rights reserved.

Molecular Identification, Characterization and Antioxidant Activities of Some Bacteria Associated with Algae in the Red Sea of Jeddah

BACKGROUND AND OBJECTIVE

Algae-associated bacteria produce secondary metabolites that have a great biological impact. The aim of this study was isolation, identification and evaluation the antioxidant activities of the associated bacteria of seven algae, Padina pavonica, Dictyota dichotoma, Cystoseira myrica, Halimeda opuntia, Ulva lactuca, Digenea simplex and Jania sp. The bacteria were isolated, characterized and identified. Identification was carried out using 16S rRNA gene sequencing.

MATERIALS AND METHODS

The identified bacteria were belonging to 6 families, Alteromonadaceae, Bacillaceae, Lactobacillaceae, Pseudomonadaceae, Rhodobacteraceae and Vibrionaceae and 9 genera. The identified bacteria were belonging to genera, Alteromonas, Bacillus, Lysinibacillus Vibrio, Lactobacillus, Paracoccus, Leisingera, Pseudomonas and Pseudovibrio. The antioxidant activities of the bacterial ethyl acetate extracts was examined by scavenging DPPH (2,2-diphenyl-1-picrylhydrazyl) and FRAP (Ferric Reducing Antioxidant Power) methods.

RESULTS

Out of the 17 isolated bacteria, Lactobacillus plantarum showed 95.7% free radical scavenging with EC50 = 17.7 μg mL-1, which is nearly similar to the positive control (Butylated Hydroxytoluene, BHT). The FRAP value of Lactobacillus extract was 2.00 mM ferric equivalent/mg of the extract. Phytochemical analysis of the bacterial extract revealed the presence of some secondary metabolites such as steroids, saponins, tannins, flavonoids, anthocyanin and betacyanin in all tested extracts.

CONCLUSION

The Red Sea algal associated bacteria have a great antioxidant potential that can be used in pharmaceutical industries.

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.

Mediterranean agro-industrial wastes as valuable substrates for lignocellulolytic enzymes and protein production by solid-state fermentation

BACKGROUND

Mediterranean agro-food industries (such as wineries, breweries and olive mills) dispose of great amounts of waste. This generates environmental problems, and the waste has a low nutritional value for use as animal feed. In this sense, solid-state fermentation (SSF) can increase the nutritional value of these wastes and simultaneously produce lignocellulolytic enzymes.

RESULTS

All fermented wastes were enriched in protein by the three fungi studied. Aspergillus ibericus was the fungus with the biggest increase of protein, which ranged from 1.4 times to 6.2 times with respect to unfermented wastes. Likewise, A. ibericus achieved the maximum cellulase and xylanase activities. The relationships among substrates composition, fungi used and SSF performance were evaluated by principal components analysis. The high content of cellulose and hemicellulose favoured lignocellulolytic enzymes production, and the phenolics content was negatively correlated with enzymes production and with the increase of protein by SSF. Furthermore, the scanning electron microscopy analysis showed the growth of fungi over solid wastes, the formation of conidiophores and the changes in their structures.

CONCLUSION

The nutritional value of Mediterranean wastes was improved and other value-added products such as lignocellulolytic enzymes were produced in the same process, which could facilitate the efficient reuse of these wastes. © 2018 Society of Chemical Industry.

Purification and biochemical characterization of a novel thermostable serine alkaline protease from Aeribacillus pallidus C10: a potential additive for detergents

An extracellular thermostable alkaline serine protease enzyme from Aeribacillus pallidus C10 (GenBank No: KC333049), was purified 4.85 and 17. 32-fold with a yield of 26.9 and 19.56%, respectively, through DE52 anion exchange and Probond affinity chromatography. The molecular mass of the enzyme was determined through sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), with approximately 38.35 kDa. The enzyme exhibited optimum activity at pH 9 and at temperature 60 °C. It was determined that the enzyme had remained stable at the range of pH 7.0-10.0, and that it had preserved more than 80% of its activity at a broad temperature range (20-80 °C). The enzyme activity was found to retain more than 70% and 55% in the presence of organic solvents and commercial detergents, respectively. In addition, it was observed that the enzyme activity had increased in the presence of 5% SDS. KM and Vmax values were calculated as 0.197 mg/mL and 7.29 μmol.mL-1.min-1, respectively.

Characterization of haloalkalophilic organic solvent tolerant protease for chitin extraction from shrimp shell waste

Halophilic organic solvent tolerant protease (HOSP) producing Paracoccus saliphilus APCMST-CS5 was isolated from the marine sediment samples and identified through 16S rRNA sequence analysis. P. saliphilus APCMST-CS5 registered maximum HOSP production of 1,321.70U/ml in the medium contained the most significant parameters such as shrimp shell powder (SSP), CaCl₂, NaCl, and sardinella powder (SP), obtained through Placket-Burman and Response Surface Methods. HOSP was further purified to 22.68 fold purity with 29.71 U/mg specific activity and its molecular weight was 39kDa. The HOSP was stable at 60°C, 9.0 pH, 3.0M NaCl concentration and it also showed maximum activity at other tested parameters. Interestingly the purified HOSP showed better antibiofilm ability against tested pathogens. Also, the HOSP effectively deproteinized (85.64%) shrimp shell chitin which in turn maximum and exhibited higher antioxidant activity. The commercial and experimental shrimp shell chitin showed similar peak pattern in FTIR and ¹³C CP/MAS NMR spectral analysis.

Production, purification and characterization of halophilic organic solvent tolerant protease from marine crustacean shell wastes and its efficacy on deproteinization

The quantum of marine fish wastes produced by fish processing industries has necessitated to search new methods for its disposal. Hence, this study is focused on production and purification of halophilic organic solvent tolerant protease (HOSP) from marine Alcaligenes faecalis APCMST-MKW6 using marine shell wastes as substrate. The candidate bacterium was isolated from the marine sediment of Manakudi coast and identified as A. faecalis APCMST-MKW6. The purified protease showed 16.39-fold purity, 70.34 U/mg specific activity with 21.67 % yield. The molecular weight of the purified alkaline protease was 49 kDa. This purified protease registered maximum activity at pH 9 and it was stable between pH 8–9 after 1.30 h of incubation. The optimum temperature registered was 60 °C and it was stable between 50 and 60 °C even after 1.30 h of incubation. This enzyme also showed maximum activity at 20 % NaCl concentration. Further, manganese chloride, magnesium chloride, calcium chloride and barium chloride influenced this enzyme activity remarkably and it was also found to be enhanced by many of the tested surfactants and solvents. The candidate bacterium effectively deproteinized the shrimp shell waste compared to the other tested crustaceans shell wastes and also attained maximum antioxidant activity.

Production, purification and characterization of a thermotolerant alkaline serine protease from a novel species Bacillus caseinilyticus

Alkaline proteases are important enzymes in many industrial applications, especially as additives in laundry detergent industry. Though there are a number of Bacillus species which are reported to be producing proteases, the efficiency of a protease produced by a novel strain has to be studied in comparison to the others. Hence, in this study, an alkaline serine protease produced by a novel species Bacilluscaseinilyticus was purified and characterized for its possible usage in detergent industry. Ammonium sulphate, dialysis and DEAE column chromatographic methods were used for purification of the isolated alkaline protease. The molecular weight of the protease was determined by SDS-PAGE and it was found to be 66 kDa. Peptide mass fingerprinting (PMF) was carried out using MALDI-TOF-TOF mass spectrometry and the peptides were found to be similar to that of subtilisin protease. Specific activity of purified protein was found to be 89.2 U/mg. Optimum pH and temperature for enzyme activity were at pH 8 and 60 °C, respectively, showing stability with 10 mM CaCl₂. Phenyl methyl sulphonyl fluoride (PMSF) at both 5 and 10 mM concentrations completely inhibited the enzyme activity suggesting its serine nature. EDTA, metal ions Mg²⁺ and Ca²⁺ increased the enzyme activity. The one factor at a time optimisation of the protease production was carried to identify the important factors that affect its production. After optimisation, the protease was produced at lab scale, purified and characterised. This alkali, thermotolerant serine protease was found to be significantly stable in the presence of various surfactants and H₂O_2. Also, it was successfully able to remove blood stain when used as an additive along with commercial detergent suggesting its potential application in the laundry detergent industry.

Identification of a New Marine Bacterial Strain SD8 and Optimization of Its Culture Conditions for Producing Alkaline Protease

While much attention has been given to marine microorganisms for production of enzymes, which in general are relatively more stable and active compared to those from plants and animals, studies on alkaline protease production from marine microorganisms have been very limited. In the present study, the alkaline protease producing marine bacterial strain SD8 isolated from sea muds in the Geziwo Qinhuangdao sea area of China was characterized and its optimal culture conditions were investigated. Strain SD8 was initially classified to belong to genus Pseudomonas by morphological, physiological and biochemical characterizations, and then through 16S rDNA sequence it was identified to be likely Pseudomonas hibiscicola. In addition, the culture mediums, carbon sources and culture conditions of strain SD8 were optimized for maximum production of alkaline protease. Optimum enzyme production (236U/mL when cultured bacteria being at 0.75 mg dry weight/mL fermentation broth) was obtained when the isolate at a 3% inoculum size was grown in LB medium at 20 mL medium/100mL Erlenmeyer flask for 48h culture at 30°C with an initial of pH 7.5. This was the first report of strain Pseudomonas hibiscicola secreting alkaline protease, and the data for its optimal cultural conditions for alkaline protease production has laid a foundation for future exploration for the potential use of SD8 strain for alkaline protease production.

Deproteinization potential and antioxidant property of haloalkalophilic organic solvent tolerant protease from marine Bacillus sp. APCMST-RS3 using marine shell wastes

The current increase in the vast amount of marine crustacean shell waste produced by the fish processing industries has led to the need to find new methods for its disposal. Hence, the present study was carried out via marine shell wastes as substrate for protease production. The maximum production (4000.65 U/ml) from Bacillus sp. APCMST-RS3 was noticed in 3:1% shrimp and oyster shell powder (SOSP) as substrate. Purified protease showed 53.22% and 22.66% enzyme yield; 3.48 and 8.49 fold purity with 40 kDa molecular weight; whereas, its Km and Vmax values were 0.6666 g/l, 1111.11 U/ml. This enzyme showed optimum activity at pH 9 and 60 °C temperature. Also, it retained maximum protease activity in the presence of NaCl (2.5 M), surfactants (Tween 20, 40, 60, 80 and SDS) and metal ions (MnCl2, CaCl2, HgCl2 and BaCl2) and solvents. The candidate bacterium effectively deproteinized (84.35%) shrimp shell and its antioxidant potentials.