Bioconversion of shellfish chitin wastes for the production of Bacillus subtilis W-118 chitinase

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.

Microbial decomposition of crustacean shell for production of bioactive metabolites and study of its fertilizing potential

Crustacean shell waste disposal is considered as biggest problem in seafood processing centers. Incineration and landfilling are the commonest ways of disposal of the waste which causes environmental pollution. Microbial bio-conversion is one of the promising approaches to minimize the wastes by utilizing the same for deriving different value added metabolites. In this perspective, chitinase- and protease-producing bacterial strains were isolated from shrimp culture pond, and the potent isolate was subsequently identified as Alcaligenes faecalis SK10. Fermentative optimization of the production of chitinase (85.42 U/ml), protease (58.57 U/ml), and their catalytic products, viz., N-acetylamino sugar (84 μg/ml) and free amino acids (112 μg/ml), were carried out by utilizing shrimp and crab shell powder as principal substrate. The fermented hydrolysate (FH) was subsequently applied to evaluate its potential to be a candidate fertilizer for the growth of leguminous plant Pisum sativum and Cicer arietinum, and the results were compared with chitin, chitosan, and commercial biofertilizer amended group. The results revealed that FH have paramount potential to improve plants morpho-physiological parameters like stem and root length, chlorophyll, cellular RNA, protein content, and soil physico-chemical parameters like total nitrogen, magnesium, calcium, phosphorus, and potassium significantly (p < 0.05). Moreover, the application of FH also selectively encouraged the growth of free-living nitrogen-fixing bacteria, Rhizobium, phosphate-solubilizing bacteria in the soil by 4.82- and 5.27-, 5.57- and 4.71, and 7.64- and 6.92-fold, respectively, in the rhizosphere of P. sativum and C. arietinum, which collectively is a good sign for an ideal biofertilizer. Co-supplementation of FH with commercial PGPR-biofertilizer significantly influenced the morpho-physiological attributes of plant and physico-chemical and microbial attributes of soil. The study validated proficient and sustainable utilization of fermented hydrolysate of waste crustacean shell as biofertilizer.

Purification, characterization, and antifungal activity of Bacillus cereus strain NK91 chitinase from rhizospheric soil samples of Himachal Pradesh, India

Newly isolated Bacillus cereus strain NK91 was characterized for extracellular chitinase production. Partially purified chitinase showed a molecular weight of 43.7 kDa in SDS-PAGE analysis. The optimum pH and temperature for the partially purified enzyme were 7.0 and 40°C, respectively. The addition of Mn²⁺ resulted in a 21% increase in enzyme activity as compared to the control. The V_max and K_m of the enzyme were determined as 76.9 μmol/min and 0.07 mg/mL, respectively. This enzyme exhibited stronger antifungal activity towards Fusarium oxysporum (66.7%), Rhizoctonia solani (64.6%), and Colletotrichum gloeosporioides (63%), and transmission electron microscopy and scanning transmission electron microscopy analysis showed considerable changes in cell wall structure with the treatment of purified chitinase as compared to control. Therefore, this enzyme reveals its biocontrol potential against potent phytopathogens in agriculture that can be helpful in swapping harmful as well as expensive fungicides.

Enzymatic approaches in the bioprocessing of shellfish wastes

Several tonnes of shellfish wastes are generated globally due to the mass consumption of shellfish meat from crustaceans like prawn, shrimp, lobster, crab, Antarctic krill, etc. These shellfish wastes are a reservoir of valuable by-products like chitin, protein, calcium carbonate, and pigments. In the present scenario, these wastes are treated chemically to recover chitin by the chitin and chitosan industries, using hazardous chemicals like HCl and NaOH. Although this process is efficient in removing proteins and minerals, the unscientific dumping of harmful effluents is hazardous to the ecosystem. Stringent environmental laws and regulations on waste disposal have encouraged researchers to look for alternate strategies to produce near-zero wastes on shellfish degradation. The role of enzymes in degrading shellfish wastes is advantageous yet has not been explored much, although it produces bioactive rich protein hydrolysates with good quality chitin. The main objective of the review is to discuss the potential of various enzymes involved in shellfish degradation and their opportunities and challenges over chemical processes in chitin recovery.

A Real-Time Fluorescent Reverse Transcription Quantitative PCR Assay for Rapid Detection of Genetic Markers' Expression Associated with Fusarium Wilt of Banana Biocontrol Activities in Bacillus

Fusarium wilt of banana, caused by Fusarium oxysporum f. sp. cubense (Foc), especially Tropical Race 4 (TR4), seriously threatens banana production worldwide. There is no single effective control measure, although certain Bacillus strains secrete antibiotics as promising disease-biocontrol agents. This study identified five Bacillus strains displaying strong antibiotic activity against TR4, using a systemic assessment for presence/absence of genetic markers at genome level, and expression profiles at transcriptome level. A conventional PCR with 13 specific primer pairs detected biocontrol-related genes. An accurate, quantitative real-time PCR protocol with novel designed specific primers was developed to characterise strain-specific gene expression, that optimises strain-culturing and RNA-isolation methodologies. Six genes responsible for synthesising non-ribosomal peptide synthetase biocontrol metabolites were detected in all five strains. Three genes were involved in synthesising three Polyketide synthetase metabolites in all five strains, but the macrolactin synthase gene mln was only detected in WBN06 and YN1282-2. All five Bacillus strains have the genes dhb and bioA, essential for synthesising bacillibactin and biotin. However, the gene sboA, involved in subtilisin synthesis, is absent in all five strains. These genes' expression patterns were significantly different among these strains, suggesting different mechanisms involved in TR4 biocontrol. Results will help elucidate functional genes' biocontrol mechanisms.

Identification and Characterization of a Newly Isolated Chitinase-Producing Strain Bacillus licheniformis SSCL-10 for Chitin Degradation

Chitinases or chitinolytic enzymes have different applications in the field of medicine, agriculture, and industry. The present study is aimed at developing an effective hyperchitinase-producing mutant strain of novel Bacillus licheniformis. A simple and rapid methodology was used for screening potential chitinolytic microbiota by chemical mutagenesis with ethylmethane sulfonate and irradiation with UV. There were 16 mutant strains exhibiting chitinase activity. Out of the chitinase-producing strains, the strain with maximum chitinase activity was selected, the protein was partially purified by SDS-PAGE, and the strain was identified as Bacillus licheniformis (SSCL-10) with the highest specific activity of 3.4 U/mL. The induced mutation model has been successfully implemented in the mutant EMS-13 (20.2 U/mL) that produces 5-6-fold higher yield of chitinase, whereas the mutant UV-11 (13.3 U/mL) has 3-4-fold greater chitinase activity compared to the wild strain. The partially purified chitinase has a molecular weight of 66 kDa. The wild strain (SSCL-10) was identified as Bacillus licheniformis using 16S rRNA sequence analysis. This study explores the potential applications of hyperchitinase-producing bacteria in recycling and processing chitin wastes from crustaceans and shrimp, thereby adding value to the crustacean industry.

Production and Potential Applications of Bioconversion of Chitin and Protein-Containing Fishery Byproducts into Prodigiosin: A Review

The technology of microbial conversion provides a potential way to exploit compounds of biotechnological potential. The red pigment prodigiosin (PG) and other PG-like pigments from bacteria, majorly from Serratia marcescens, have been reported as bioactive secondary metabolites that can be used in the broad fields of agriculture, fine chemicals, and pharmacy. Increasing PG productivity by investigating the culture conditions especially the inexpensive carbon and nitrogen (C/N) sources has become an important factor for large-scale production. Investigations into the bioactivities and applications of PG and its related compounds have also been given increased attention. To save production cost, chitin and protein-containing fishery byproducts have recently been investigated as the sole C/N source for the production of PG and chitinolytic/proteolytic enzymes. This strategy provides an environmentally-friendly selection using inexpensive C/N sources to produce a high yield of PG together with chitinolytic and proteolytic enzymes by S. marcescens. The review article will provide effective references for production, bioactivity, and application of S. marcescens PG in various fields such as biocontrol agents and potential pharmaceutical drugs.

Biocontrol potential of chitinases produced by newly isolated Chitinophaga sp. S167

A chitinolytic bacterium Chitinophaga sp. S167 producing extracellular chitinases was isolated from a soil sample in India. The extracellular chitinases produced by S167 were concentrated by ammonium sulphate precipitation (AS70) and seven bands corresponding to chitinases were observed by zymography. Optimum temperature and pH of AS70 were between 40 and 45 °C and pH 6.0 respectively with high stability at 20-40 °C and pH 5-7. AS70 inhibited the growth of Fusarium oxysporum, Alternaria alternata and Cladosporium sp. in vitro. The culture conditions for the high level production of extracellular chitinases were optimized resulting in 48-folds higher chitinase production. As the combination of chitinases could be more potent in biocontrol of plant diseases, it was checked if AS70 could control postharvest fungal infection caused by Fusarium oxysporum on tomatoes. AS70 treated tomatoes showed significant lower incidence of infection (11%) by F. oxysporum as compared with 100% in the control at 5 days post inoculation. Further, AS70 caused significant mortality in second stage juveniles of root knot nematode, Meloidogyne incognita, a major agriculture pest responsible for economic losses in agriculture. This study highlights the antifungal and nematicidal activity of chitinases produced by Chitinophaga sp. S167. To the best of our knowledge, this is the first report of the biocontrol potential of the chitinases produced by Chitinophaga sp.

Partial purification and characterization of chitinase produced by Bacillus licheniformis B307

The optimal conditions required for chitinase production from Bacillus licheniformis B307 strain, obtained from Syrian soil, were studied. Optimization experiments were carried out under submerged fermentation conditions, and colloidal chitin was the source of carbon. Luria broth medium supplied with 0.5% colloidal chitin was the optimum medium for chitinase production. The maximum chitinase yield was obtained at 30 °C, pH6, incubation time 14 days, and 150 rpm. The optimum chitinase activity was achieved at 60 °C and pH6. The chitinase activity with unmodified medium was 1.9 U/mL which then enhanced about eight folds to reach 14.2 U/mL under optimized submerged fermentation conditions. An extracellular chitinase of Bacillus licheniformis B307 was partially purified using ammonium sulfate precipitation followed by concentration with various sizes of concentrator tubes. The chitinase was partially purified 8.24 fold and specific enzyme activity increased 2.08 fold (2 U/mg). Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) of partial purified chitinase exhibited a molecular weight (M_r) near to 36 and 42kDa. These results make it possible to invest in this strain to produce chitinase to be used as antifungal, food additives and other applications.

Antiproliferative, neurotoxic, genotoxic and mutagenic effects of toxic cyanobacterial extracts

Cyanobacteria are the rich resource of various secondary metabolites including toxins with broad pharmaceutical significance. The aim of this work was to evaluate the antiproliferative, neurotoxic, genotoxic and mutagenic effects of cyanobacterial extracts containing Microcystin-LR (MCLR) in vitro. ELISA analysis results showed that MCLR contents of five cyanobacterial extracts were 2.07 ng/mL, 1.43 ng/mL, 1.41 ng/mL, 1.27 ng/mL, and 1.12 ng/mL for Leptolyngbya sp. SB1, Phormidium sp. SB4, Oscillatoria earlei SB5, Phormidium sp. SB2, Uncultured cyanobacterium, respectively. Phormidium sp. SB4 and Phormidium sp. SB2 extracts had the lowest neurotoxicity (86% and 79% cell viability, respectively) and Oscillatoria earlei SB5 extracts had the highest neurotoxicity (47% cell viability) on PC12 cell at 1000 µg/ml extract concentration. Leptolyngbya sp. SB1 and Phormidium sp. SB2 showed the highest antiproliferative effect (92% and 77% cell death) on HT29 cell. On the other hand, all concentrations of five toxic cyanobacterial extracts induced DNA damage between 3.0% and 1.3% of tail intensity and did not cause any direct mutagenic effect at the 1000 µg/plate cyanobacterial extracts. These results suggest that cyanobacteria-derived MCLR is a promising candidate for development of effective agents against colon cancer.

Cloning, characterization and substrate degradation mode of a novel chitinase from Streptomyces albolongus ATCC 27414

A novel chitinase gene was cloned from Streptomyces albolongus ATCC 27414, and expressed successfully in Escherichia coli BL21. The recombinant enzyme (SaChiA4) belongs to glycoside hydrolases (GH) family 18 and consists of a catalytic domain and a chitin binding domain (CBD) in its C-terminus. SaChiA4 was purified homogeneously (specific activity of 66.2 U/mg with colloidal chitin as substrate), and showed a molecular mass of approximately 47 kDa. SaChiA4 showed its optimal activity at pH 5.0 and 55 °C and exhibited remarkable pH and temperature stability. SaChiA4 has been proved to have a higher specificity toward glycosides containing acetyl groups and hydrolyzes the substrates in a non-processive manner with higher ability to produce (GlcNAc)₂ and GlcNAc. The results indicated that SaChiA4 is a novel endo-type chitinase, which has potential applications in the treatment of chitin wastes and the production of (GlcNAc)₂.

Necrotrophic Mycoparasites and Their Genomes

Mycoparasitism is a lifestyle where one fungus establishes parasitic interactions with other fungi. Species of the genus Trichoderma together with Clonostachys rosea are among the most studied fungal mycoparasites. They have wide host ranges comprising several plant pathogens and are used for biological control of plant diseases. Trichoderma as well as C. rosea mycoparasites efficiently overgrow and kill their fungal prey by using infection structures and by applying lytic enzymes and toxic metabolites. Most of our knowledge on the putative signals and signaling pathways involved in prey recognition and activation of the mycoparasitic response is derived from studies with Trichoderma. These fungi rely on G-protein signaling, the cAMP pathway, and mitogen-activated protein kinase cascades during growth and development as well as during mycoparasitism. The signals being recognized by the mycoparasite may include surface molecules and surface properties as well as secondary metabolites and other small molecules released from the prey. Their exact nature, however, remains elusive so far. Recent genomics-based studies of mycoparasitic fungi of the order Hypocreales, i.e., Trichoderma species, C. rosea, Tolypocladium ophioglossoides, and Escovopsis weberi, revealed not only several gene families with a mycoparasitism-related expansion of gene paralogue numbers, but also distinct differences between the different mycoparasites. We use this information to illustrate the biological principles and molecular basis of necrotrophic mycoparasitism and compare the mycoparasitic strategies of Trichoderma as a "model" mycoparasite with the behavior and special features of C. rosea, T. ophioglossoides, and E. weberi.

Production of N-Acetyl-d-glucosamine from Mycelial Waste by a Combination of Bacterial Chitinases and an Insect N-Acetyl-d-glucosaminidase

N-Acetyl-d-glucosamine (GlcNAc) has great potential to be used as a food additive and medicine. The enzymatic degradation of chitin-containing biomass for producing GlcNAc is an eco-friendly approach but suffers from a high cost. The economical efficiency can be improved by both optimizing the member and ratio of the chitinolytic enzymes and using new inexpensive substrates. To address this, a novel combination of bacterial and insect chitinolytic enzymes was developed in this study to efficiently produce GlcNAc from the mycelia of Asperillus niger, a fermentation waste. This enzyme combination contained three bacterial chitinases (chitinase A from Serratia marcescens (SmChiA), SmChiB, SmChiC) and one insect N-acetyl-d-glucosaminidase from Ostrinia furnacalis (OfHex1) in a ratio of 39.1% of SmChiA, 26.7% of SmChiB, 32.9% of SmChiC, and 1.3% of OfHex1. A yield of 6.3 mM (1.4 mg/mL) GlcNAc with a purity of 95% can be obtained from 10 mg/mL mycelial powder in 24 h. The enzyme combination reported here exhibited 5.8-fold higher hydrolytic activity over the commercial chitinase preparation derived from Streptomyces griseus.

An Amphiprotic Novel Chitosanase from Bacillus mycoides and Its Application in the Production of Chitooligomers with Their Antioxidant and Anti-Inflammatory Evaluation

The objectives of this investigation were to produce a novel chitosanase for application in industries and waste treatment. The transformation of chitinous biowaste into valuable bioactive chitooligomers (COS) is one of the most exciting applications of chitosanase. An amphiprotic novel chitosanase from Bacillus mycoides TKU038 using squid pen powder (SPP)-containing medium was retrieved from a Taiwan soil sample, which was purified by column chromatography, and characterized by biochemical protocol. Extracellular chitosanase (CS038) was purified to 130-fold with a 35% yield, and its molecular mass was roughly 48 kDa. CS038 was stable over a wide range of pH values (4-10) at 50 °C and exhibited an optimal temperature of 50 °C. Interestingly, the optimum pH values were estimated as 6 and 10, whereas CS038 exhibited chitosan-degrading activity (100% and 94%, respectively). CS038 had Km and Vmax values of 0.098 mg/mL and 1.336 U/min, separately, using different concentrations of water-soluble chitosan. A combination of the high performance liquid chromatography (HPLC) and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometer data revealed that the chitosan oligosaccharides obtained from the hydrolysis of chitosan by CS038 comprise oligomers with multiple degrees of polymerization (DP), varying from 3-9, as well as CS038 in an endolytic fashion. The TKU038 culture supernatant and COS mixture exhibited 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activities. The COS activities were dose dependent and correlated to their DP. The COS with high DP exhibited enhanced DPPH radical scavenging capability compared with COS with low DP. Furthermore, the COS exhibited inhibitory behavior on nitric oxide (NO) production in murine RAW 264.7 macrophage cells, which was induced by Escherichia coli O111 lipopolysaccharide (LPS). The COS with low DP possesses a more potent anti-inflammatory capability to decrease NO production (IC50, 76.27 ± 1.49 µg/mL) than that of COS with high DP (IC50, 82.65 ± 1.18 µg/mL). Given its effectiveness in production and purification, acidophilic and alkalophilic properties, stability over ranges of pH values, ability to generate COS, antioxidant activity, and anti-inflammatory, CS038 has potential applications in SPP waste treatment and industries for COS production as a medical prebiotic.

Enhanced chitinase production by Chitinolyticbacter meiyuanensis SYBC-H1 using staged pH control

The pH of a microbiological culture is important for both cell growth and chitinase accumulation, but the optimal pH is not normally the same for both. The objective of this study was to investigate the effect of pH on chitinase production by Chitinolyticbacter meiyuanensis strain SYBC-H1 (ATCC BAA-2140) in a mineral medium. The results of batch culture at different pH values showed that the optimum pH for cell growth and chitinase production varied with time, although KOH produced the best results for cell growth and chitinase production, NaOH was chosen because of cost considerations. We designed a three-stage pH control strategy using NaOH as the neutralizing agent. Maximum cell growth (1.07 g dry cell weight/l) and maximum chitinase activity (13.6 U/ml) were observed after culture at 26°C for 72 h in a mineral medium. These values were greater by 129% and 162%, respectively, and the length of time to attain maximum chitinase activity was decreased by 12 h, compared with results from an earlier study (Hao et al., 2011b).

Cloning, Expression and 3D Structure Prediction of Chitinase from Chitinolyticbacter meiyuanensis SYBC-H1

Two CHI genes from Chitinolyticbactermeiyuanensis SYBC-H1 encoding chitinases were identified and their protein 3D structures were predicted. According to the amino acid sequence alignment, CHI1 gene encoding 166 aa had a structural domain similar to the GH18 type II chitinase, and CHI2 gene encoding 383 aa had the same catalytic domain as the glycoside hydrolase family 19 chitinase. In this study, CHI2 chitinase were expressed in Escherichia coli BL21 cells, and this protein was purified by ammonium sulfate precipitation, DEAE-cellulose, and Sephadex G-100 chromatography. Optimal activity of CHI2 chitinase occurred at a temperature of 40 °C and a pH of 6.5. The presence of metal ions Fe³⁺, Fe²⁺, and Zn²⁺ inhibited CHI2 chitinase activity, while Na⁺ and K⁺ promoted its activity. Furthermore, the presence of EGTA, EDTA, and β-mercaptoethanol significantly increased the stability of CHI2 chitinase. The CHI2 chitinase was active with p-NP-GlcNAc, with the K_m and V_m values of 23.0 µmol/L and 9.1 mM/min at a temperature of 37 °C, respectively. Additionally, the CHI2 chitinase was characterized as an N-acetyl glucosaminidase based on the hydrolysate from chitin. Overall, our results demonstrated CHI2 chitinase with remarkable biochemical properties is suitable for bioconversion of chitin waste.

Application of Chitinous Materials in Production and Purification of a Poly(l-lactic acid) Depolymerase from Pseudomonas tamsuii TKU015

The management of fishery residues and plastics is considered to be a vital strategy for conserving resources and maintaining the quality of the environment. Poly(l-lactic acid) (PLA) is a commercially promising, renewable, and biodegradable plastic. In this study, a PLA depolymerase was produced in a squid pen powder (SPP) and recycled plastic waste (PLA powder)-containing medium by Pseudomonas tamsuii TKU015, a bacterial strain isolated from Taiwanese soil. This PLA depolymerase had a molecular weight of 58 kDa and was purified to homogeneity from the supernatant of a TKU015 culture. The optimum pH of TKU015 PLA depolymerase is 10, and the optimal temperature of the enzyme is 60 °C. In addition to PLA, TKU015 PLA depolymerase degraded fibrinogen and tributyrin, but did not hydrolyze casein, triolein, and poly(β-hydroxybutyrate). Taken together, these data demonstrate that P. tamsuii TKU015 produces a PLA depolymerase to utilize SPP and polylactide as carbon/nitrogen sources.

Chitinolytic Bacteria-Assisted Conversion of Squid Pen and Its Effect on Dyes and Pigments Adsorption

The aim of this work was to produce chitosanase by fermenting from squid pen, and recover the fermented squid pen for dye removal by adsorption. One chitosanase induced from squid pen powder (SPP)-containing medium by Bacillus cereus TKU034 was purified in high purification fold (441) and high yield of activity recovery (51%) by ammonium sulfate precipitation and combined column chromatography. The SDS-PAGE results showed its molecular mass to be around 43 kDa. The TKU034 chitosanase used for the chitooligomers preparation was studied. The enzyme products revealed that the chitosanase could degrade chitosan with various degrees of polymerization, ranging from 3 to 9, as well as the chitosanase in an endolytic manner. Besides, the fermented SPP was recovered and displayed a better adsorption rate (up to 99.5%) for the disperse dyes (red, yellow, blue, and black) than the water-soluble food colorants, Allura Red AC (R40) and Tartrazine (Y4). The adsorbed R40 on the unfermented SPP and the fermented SPP was eluted by distilled water and 1 M NaOH to confirm the dye adsorption mechanism. The fermented SPP had a slightly higher adsorption capacity than the unfermented, and elution of the dye from the fermented SPP was easier than from the unfermented. The main dye adsorption mechanism of fermented SPP was physical adsorption, while the adsorption mechanism of unfermented SPP was chemical adsorption.

Squid pen chitin chitooligomers as food colorants absorbers

One of the most promising applications of chitosanase is the conversion of chitinous biowaste into bioactive chitooligomers (COS). TKU033 chitosanase was induced from squid pen powder (SPP)-containing Bacillus cereus TKU033 medium and purified by ammonium sulfate precipitation and column chromatography. The enzyme was relatively more thermostable in the presence of the substrate and had an activity of 93% at 50 °C in a pH 5 buffer solution for 60 min. Furthermore, the enzyme used for the COS preparation was also studied. The enzyme products revealed various mixtures of COS that with different degrees of polymerization (DP), ranging from three to nine. In the culture medium, the fermented SPP was recovered, and it displayed a better adsorption rate (up to 96%) for the disperse dyes than the water-soluble food colorants, Allura Red AC (R40) and Tartrazne (Y4). Fourier transform-infrared spectroscopic (FT-IR) analysis proved that the adsorption of the dyes onto fermented SPP was a physical adsorption. Results also showed that fermented SPP was a favorable adsorber and could be employed as low-cost alternative for dye removal in wastewater treatment.

Biodegradation of shrimp biowaste by marine Exiguobacterium sp. CFR26M and concomitant production of extracellular protease and antioxidant materials: production and process optimization by response surface methodology

Twelve marine bacterial cultures were screened for extracellular protease activity, and the bacterium CFR26M which exhibited the highest activity on caseinate agar plate was identified as an Exiguobacterium sp. Significant amount of extracellular protease (5.9 ± 0.3 U/ml) and antioxidant materials, measured as 2,2'-diphenyl picrylhydrazyl (DPPH) radical scavenging activity (44.4 ± 0.5 %), was produced by CFR26M in submerged fermentation using a shrimp biowaste medium. Response surface methodology (RSM) was employed to optimize the process variables for maximum production of protease and antioxidant materials by CFR26M. Among the seven variables screened by two-level 2**(7-2) fractional factorial design, the concentration of shrimp biowaste, sugar, and phosphate was found to be significant (p ≤ 0.05). The optimum levels of these variables were determined by employing the central composite design (CCD) of RSM. The coefficient of determination (R (2)) values of 0.9039 and 0.8924 for protease and antioxidant, respectively, indicates the accuracy of the CCD models. The optimum levels of shrimp biowaste, sugar, and phosphate were 21.2, 10.5, and 2.3 % (w/v) for production of protease and 28.8, 12, and 0.32 % (w/v) for production of antioxidant material, respectively. The concentration of shrimp biowaste, sugar, and phosphate had linear and quadratic effect on both protease and antioxidant productions. RSM optimization yielded 6.3-fold increases in protease activity and 1.6-fold in antioxidant material production. The crude protease of CFR26M had a maximum activity at 32 ± 2 °C with pH 7.6. This is the first report on the use of marine Exiguobacterium sp. for concomitant production of protease and antioxidant materials from shrimp biowaste.

Production and purification of a fungal chitosanase and chitooligomers from Penicillium janthinellum D4 and discovery of the enzyme activators

Chitosanases have received much attention because of their wide range of applications. Although most fungal chitosanases use sugar as their major carbon source, in the present work, a chitosanase was induced from a squid pen powder (SPP)-containing Penicillium janthinellum D4 medium and purified by ammonium sulphate precipitation and combined column chromatography. The purified D4 chitosanase exhibited optimum activity at pH 7-9, 60°C and was stable at pH 7-11, 25-50°C. The D4 chitosanase that was used for chitooligomers preparation was studied. The enzyme products revealed various chitooligomers with different degrees of polymerisation (DP) from 3 to 9, as determined by a MALDI-TOF mass spectrometer, confirming the endo-type nature of the D4 chitosanase. D4 chitosanase activity was significantly inhibited by Cu(2+), Mn(2+), and EDTA. However, Fe(2+) activated or inhibited D4 chitosanases at different concentrations. The D4 chitosanase was also activated by some small synthetic boron-containing molecules with boronate ester side chains.

Fish processing wastes for microbial enzyme production: a review

Fishery processing industries generate large amounts of by-products. The disposal of these wastes represents an increasing environmental and health problem. To avoid wasting these by-products, various disposal methods have been applied including, ensilation, fermentation, hydrolysate and fish oil production. Interestingly, fish by-products provide an excellent nutrient source for microbial growth useful in enzyme production process, which is largely governed by the cost related to the growth media. Fish wastes (heads, viscera, chitinous material, wastewater, etc.) were prepared and tested as growth substrates for microbial enzymes production such as protease, lipase, chitinolytic and ligninolytic enzymes. This new approach described in this review can reduce environmental problems associated with waste disposal and, simultaneously, lower the cost of microbial enzyme production.

The use of amino sugars by Bacillus subtilis: presence of a unique operon for the catabolism of glucosamine

B. subtilis grows more rapidly using the amino sugar glucosamine as carbon source, than with N-acetylglucosamine. Genes for the transport and metabolism of N-acetylglucosamine (nagP and nagAB) are found in all the sequenced Bacilli (except Anoxybacillus flavithermus). In B. subtilis there is an additional operon (gamAP) encoding second copies of genes for the transport and catabolism of glucosamine. We have developed a method to make multiple deletion mutations in B. subtilis employing an excisable spectinomycin resistance cassette. Using this method we have analysed the contribution of the different genes of the nag and gam operons for their role in utilization of glucosamine and N-acetylglucosamine. Faster growth on glucosamine is due to the presence of the gamAP operon, which is strongly induced by glucosamine. Although the gamA and nagB genes encode isozymes of GlcN6P deaminase, catabolism of N-acetylglucosamine relies mostly upon the gamA gene product. The genes for use of N-acetylglucosamine, nagAB and nagP, are repressed by YvoA (NagR), a GntR family regulator, whose gene is part of the nagAB yvoA(nagR) operon. The gamAP operon is repressed by YbgA, another GntR family repressor, whose gene is expressed divergently from gamAP. The nagAB yvoA synton is found throughout the Bacilli and most firmicutes. On the other hand the ybgA-gamAP synton, which includes the ybgB gene for a small protein of unknown provenance, is only found in B. subtilis (and a few very close relatives). The origin of ybgBA-gamAP grouping is unknown but synteny analysis suggests lateral transfer from an unidentified donor. The presence of gamAP has enabled B. subtilis to efficiently use glucosamine as carbon source.

Production and purification of a protease, a chitosanase, and chitin oligosaccharides by Bacillus cereus TKU022 fermentation

A protease- and chitosanase-producing strain was isolated and identified as Bacillus cereus TKU022. The protease and chitosanase were both produced using 1.5% (w/v) shrimp head powder (SHP) as the sole carbon/nitrogen source, and these enzymes were purified from the culture supernatant. The molecular masses of the TKU022 protease and chitosanase determined using SDS-PAGE were approximately 45 and 44kDa, respectively. The high stability of the TKU022 protease toward surfactants, an optimal pH of 10 and an optimal temperature of 50-60°C suggest that this high-alkaline protease has potential applications for various industrial processes. Concomitant with the production of the TKU022 chitosanase, N-acetyl chitooligosaccharides were also observed in the culture supernatant, including (GlcNAc)(2), (GlcNAc)(4), (GlcNAc)(5), and (GlcNAc)(6) at concentrations of 201.5, 12.4, 0.5, and 0.3μg/mL, respectively, as determined using an HPLC analysis. The chitin oligosaccharides products were also characterized using a MALDI-TOF mass spectrometer. A combination of the HPLC and MALDI-TOF MS results showed that the chitin oligosaccharides of the TKU022 culture supernatant comprise oligomers with degree of polymerization (DP) from 2 to 6. Using this method, the production of a protease, a chitosanase, and chitin oligosaccharides may be useful for various industrial and biological applications.

Fermented and enzymatic production of chitin/chitosan oligosaccharides by extracellular chitinases from Bacillus cereus TKU027

Two chitinases, Chi I and Chi II, were purified from the culture supernatant of Bacillus cereus TKU027 with shrimp head powder (SHP) as the sole carbon/nitrogen source. The molecular masses of Chi I and Chi II determined using SDS-PAGE were approximately 65kDa and 63kDa, respectively. Chi I toward various surfactants showed high stability, such as SDS, Tween 20, Tween 40 and Triton X-100, and these surfactants were stimulator of Chi I chitinase activity. Concomitant with the production of Chi I and Chi II, chitin oligosaccharides were also observed in the culture supernatant, including chitobiose, chitotriose, chitotetrose and chitopentose at concentrations of 0.44mg/mL, 0.08mg/mL, 0.09mg/mL and 0.43mg/mL, respectively. Chitosan with 60% deacetylation was degraded by TKU027 crude enzyme to prepare chitooligosaccharides. MALDI-TOF MS analysis of the enzymatic hydrolyzates indicated that the products were mainly chitooligosaccharides with degree of polymerization (DP) in the 4-9 range.