Use of statistical experimental methods for optimization of collagenolytic protease production by Bacillus cereus strain SUK grown on fish scales

Microbes as a tool for the bioremediation of fish waste from the environment and the production of value-added compounds: a review

Fish are the most edible protein source worldwide and generate several remnants such as scales, viscera, head, bone, and skin. Fish wastes are not disposed of properly, which adversely affects the environment, especially the water bodies where fish processing industries dispose of their waste. Fish waste mainly contains nitrogen, oil, fat, salts, heavy metals, and organic compounds, which increase the biological oxygen demand and chemical oxygen demand. Fish waste can degrade in various ways, such as physicochemical or by enzymatic action, but using microbes is an environmentally friendly approach that can provide valuable compounds such as products such as collagen, chitin, minerals, and fish protein concentrates. This review is designed to focus on the suitability of microbes as tools for fish waste degradation and the production of certain associated. This study also provides insight into the production of other compounds such as protease, chitinase, and chitin applicability of these products. After processing, fish waste as a microbial growth media for enzyme production since microorganisms synthesize enzymes such as proteases, protein hydrolysates, lipids, and chitinase, which have broader applications in the pharmaceutical, cosmetic, biomedical material, and food processing industries.

Beauveria Bassiana Amylase-Polygalacturonase Production Using Lignocellulosic Biomass and Application in Juice Processing

Background

The search for sources of industrial biocatalysts, which are non-pathogenic and can utilise cheap nutrient sources, has been a continuous endeavour in the ~ 7 billion USD enzyme industry. Beauveria bassiana, an endophytic fungal entomopathogen, is non-pathogenic and possesses the potential to secrete various bioproducts while utilising readily available lignocellulosic biomass.

Objective

This study investigated the optimised production of two glycosyl hydrolases, amylase and polygalacturonase, by B. bassiana while utilising readily available agricultural residues. Subsequently, the industrial potential of the enzymes in the clarification of fruit juice was evaluated.

Materials and Methods

Initially, seven agro residues were screened for the concomitant production of amylase and polygalacturonase by B. bassiana SAN01. Subsequently, statistical optimisation tools, Plackett Burman Design (PBD) and Central Composite Design (CCD), were employed for the optimisation of enzyme production. The enzyme mixture was partially purified and applied in the clarification of pineapple juice.

Result

The production of B. bassiana SAN01 amylase and polygalacturonase was found to be maximal while utilising wheat bran. Subsequent to PBD and CCD optimisation, the optimal conditions for enzyme production were identified to be at 30 °C, pH 6.0 and wheat bran concentration of ~40 g.L-1. Under these optimised conditions, heightened production levels of 34.82 and 51.05 U.mL-1 were recorded for amylase and polygalacturonase, respectively, which were 179% and 187% of the initial unoptimised levels. In addition, the most effective clarification of the juice (~90%) was observed at 35 °C after an incubation time of 120 min with no significant effect on the pH and total dissolved solids.

Conclusion

B. bassiana, a well-known biocontrol agent, was shown to produce amylase and polygalacturonase using readily available agricultural residues for the first time. These enzyme production levels are the highest for these enzymes from any known endophytic fungal entomopathogen. This study further demonstrates the potential applicability of B. bassiana in other industrial processes besides its widespread use as a biopesticide.

Use of Yarrowia lipolytica to Obtain Fish Waste Functional Hydrolysates Rich in Flavoring Compounds

Fishery processing industries generate large amounts of by-products. These by-products come from fish heads, skin, bones, thorns, and viscera. The disposal of these wastes represents an increasing environmental and health problem. Nowadays, there is a growing interest in how to utilize fish materials that are not used for human consumption. Among the different solutions proposed, the use of proteolytic and lipolytic microorganisms represents a green solution for waste valorization. In this work, first we screened several conventional and non-conventional microorganisms for their proteolytic and lipolytic functions. Then, the most promising strains (Yarrowia lipolytica YL2, Y. lipolytica YL4, Bacillus amyloliquefaciens B5M and B. subtilis B5C) were tested on a fish waste-based solution. After 72 h incubation at room temperature, the supernatants obtained using the strains of Y. lipolytica showed the highest degree of hydrolysis (10.03 and 11.80%, respectively, for YL2 and YL4), the strongest antioxidant activity (86.4% in DPPH assay for YL2) and the highest formation of aldehydes (above 50% of the total volatile compounds detected). Hydrolysates of fish waste obtained with Y. lipolytica may be reused in feed and food formulations for their functional and flavoring characteristics.

Isolation, biochemical characterization, and development of a biodegradable antimicrobial film from Cirrhinus mrigala scale collagen

Collagen is a promising candidate for food and pharmaceutical applications due to its excellent biocompatibility, low antigenicity, and controlled biodegradability; however, its heavy price restricts its utilization. Fish scales generated during the processing are generally regarded as waste material and an environmental pollutant, though they are a promising source of collagen. In the present study, Cirrhinus mrigala scales were demineralized and extracted for acid-soluble collagen (ASC) using acetic acid, with a collagen yield of 2.7%. UV-Vis spectra, SDS-PAGE, FTIR analyses, and amino acid composition confirmed the type I nature of the collagen extracted. The denaturation temperature of the collagen was found to be 30.09 °C using differential scanning calorimetry (DSC). The collagen was highly soluble at acidic pH and lower NaCl concentrations while its solubility was lowered in alkaline conditions and NaCl concentrations above 0.5 M. The collagen exhibited good emulsifying potential with an emulsion activity index (EAI) and emulsion stability index (ESI) of 21.49 ± 0.22 m² g^-1 and 15.67 ± 0.13 min, respectively. Owing to the good physicochemical characteristics of the extracted collagen, collagen-chitosan-neem extract (CCN) films were prepared subsequently which showed good antimicrobial activity against Bacillus subtilis NCIM 2635, Staphylococcus aureus NCIM 2654, Escherichia coli NCIM 2832, and Pseudomonas aeruginosa NCIM 5032, suggesting the potential of collagen in the development of antimicrobial films. These results demonstrate that the collagen from fish waste could be valorized and used effectively along with chitosan and neem extract for the synthesis of novel biodegradable films with antimicrobial efficacy.

Optimization of Bacillus cereus Fermentation Process for Selenium Enrichment as Organic Selenium Source

Selenium is an essential trace element and micronutrient for human health. Application of organic selenium in plants and microorganisms as trace element supplement is attracting more and more attention. In this study, Bacillus cereus, an important probiotic, was used for selenium enrichment with sodium selenite as selenium source. The growth curve of B. cereus was investigated, and 150 μg/ml was selected as the concentration of selenium for B. cereus fermentation. With application of response surface methodology, the optimal fermentation conditions were obtained as follows: inoculation quantity of 7%, culture temperature of 33°C, and shaking speed of 170 rpm, leading to the maximal selenium conversion ratio of 94.3 ± 0.2%. Field emission scanning electron microscope and energy dispersive spectrometry evidenced that inorganic selenium had been successfully transformed. This study may contribute to get a strain with high Se conversion ratio, so as to extract organic selenium in the form of selenoprotein to be used for further application.

Enhanced xylanase and endoglucanase production from Beauveria bassiana SAN01, an entomopathogenic fungal endophyte

This study was undertaken to explore alternative applications of the widely known entomopathogenic/endophytic fungus, Beauveria bassiana, besides its sole use as a biocontrol agent. B. bassiana SAN01, was investigated for the production of two glycoside hydrolases, xylanase and endoglucanase under submerged conditions. Among the different biomass tested, wheat bran provided the best results for both xylanase and endoglucanase, and their production levels were further enhanced using response surface methodology. Under optimised conditions, heightened yields of 1061 U/ml and 23.03 U/ml were observed for xylanase and endoglucanase, respectively, which were 3.44 and 1.35 folds higher than their initial yields. These are the highest ever production levels reported for xylanase and endoglucanase from any B. bassiana strain or any known entomopathogenic fungi. Furthermore, the efficacy of xylanase/endoglucanase cocktail in the saccharification of sugarcane bagasse was evaluated. The highest amount of reducing sugar released from the pretreated biomass by the action of the crude Beauveria enzyme cocktail was recorded at 30°C after 8 h incubation. The significant activities of the hydrolytic enzymes recorded with B. bassiana in this study thus present promising avenues for the use of the entomopathogen as a new source of industrial enzymes and by extension, other biotechnological applications.

A biological clean processing approach for the valorization of speckled shrimp Metapenaeus monoceros by-product as a source of bioactive compounds

The efficiency of the proteolytic strain Anoxybacillus kamchatkensis M1V in the fermentation of speckled shrimp by-product was investigated for the recovery of a deproteinized bioactive hydrolysate. The biological activities of the resulting hydrolysate were also examined by applying several antioxidant and enzyme inhibitory assays. The strain M1V was found to produce high level of protease activity (2000 U/mL) when grown in media containing only shrimp powder at 25 g/L. The crude protease displayed a significant deproteinization capabiliy, with the best efficiency (48%) being recorded for an enzyme to substrate (E/S) ratio of 30 U/mg. Following the deproteinization, chitin was recovered and the authenticity was confirmed by Fourier-transform infrared spectroscopy (FTIR) analysis. On the other hand, the obtained hydrolysate showed a significant enzymatic inhibitory potential against acetylcholinesterase, tyrosinase, amylase, and angiotensin I convertase, and a strong antioxidant activity. Graphical Abstract.

Statistical media optimization for the production of clinical uricase from Bacillus subtilis strain SP6

In this study, a potent uricase producing organism was isolated by a thorough screening and identified as Bacillus subtilis strain SP6 by using 16s rDNA sequencing. Response surface methodological optimization was employed for the enhanced production of uricase from newly isolated Bacillus subtilis strain SP6. In media optimization studies, Plackett Burman (PB) design was used for the selection of the critical media components; which were further optimized using central composite design (CCD). Lactose, soya peptone, uric acid and FeSO₄.7H₂O were found to be the critical factors influencing the enzyme production. Optimum uricase production with these factors was deduced using central composite design. Significant level of the factors were 12.2 g/L of lactose, 12.79 g/L of soya peptone, 2.55 g/L of uric acid and 0.00325 g/L FeSO₄.7H₂O. Use of statistical optimization upsurges uricase yield from 1.2 U/ml to 15.87 U/ml enhancing the overall production by 13.23 fold; which confirms that the model is effective for process optimization.