Utilization of protein-rich residues in biotechnological processes

Microbial assemblage for solid waste bioremediation and valorization with an essence of bioengineering

Environmental solid waste bioremediation is a method of treating contaminated solid waste that involves changing ecological conditions to foster the growth of a broad spectrum of microorganisms and the destruction of the target contaminants. A wide range of microorganisms creates metabolites that may break down and change solid waste-based pollution to various value-added molecules. Diverse bioremediation technologies, their limitations, and the procedure involve recycling solid waste materials from the environment. The existing environmental solid waste disposal services are insufficient and must be upgraded with more lucrative recovery, recycling, and reuse technologies to decrease the enormous expenditures in treatment procedures. Bioremediation of solid waste eliminates the toxic components. It restores the site with the advent of potential microbial communities towards solid waste valorization utilizing agriculture solid waste, organic food waste, plastic solid waste, and multiple industrial solid wastes.Bioengineering on diverse ranges of microbial regimes has accelerated to provide extra momentum toward solid waste recycling and valorization. This approach increases the activity of bioremediating microbes in the commercial development of waste treatment techniques and increases the cost-effective valuable product generation. This framework facilitates collaboration between solid waste and utilities. It can aid in establishing a long-term management strategy for recycling development with the advent of a broad spectrum of potential microbial assemblages, increasing solid waste contamination tolerance efficiency and solid waste degradability. The current literature survey extensively summarises solid waste remediation valorization using a broad spectrum of microbial assemblages with special emphasis on bioengineering-based acceleration. This approach is to attain sustainable environmental management and value-added biomolecule generation.

Combining the production of L-lactic acid with the production of feed protein concentrates from alfalfa

The production of L-lactic acid was investigated in combination with the production of protein concentrates in the frame of a green biorefinery for efficient utilization of grasses and legume crops. Alfalfa green juice was the sole substrate utilized for initial lactic acid fermentation with Lactobacillus salivarius, Lactobacillus paracasei or Bacillus coagulans in order to drop the pH and precipitate the plant proteins present in the juice. Afterwards, proteins were separated by microfiltration with 40-42% of protein recovery into protein concentrates, suited for feeding monogastric animals. The (residual) brown juice was investigated as source of nutrients for producing L-lactic acid from glucose or xylose with B. coagulans A107 or B. coagulans A166, respectively. Fermentation of glucose (30, 60, 100 g L^-1) resulted in productivities of 2.8-4.0 g L^-1 h^-1 and yields of 0.85-0.91 g LA per g consumed glucose. Fermentation of xylose (30, 60 g L^-1) resulted productivities of 1.1-2.3 g L^-1 h^-1 and yields of 0.83-0.88 g LA per g consumed xylose. Comparing different brown juices, initial green juice fermentation with B. coagulans is recommended if the brown juice is to be used for producing L-lactic acid. Based on our results, it is possible to combine protein recovery with lactic acid production, and the brown juice proved to be a good nutrient source for L-lactic acid production with high optical purities.

Bioconversion of Fish Discards through the Production of Lactic Acid Bacteria and Metabolites: Sustainable Application of Fish Peptones in Nutritive Fermentation Media

In the current work, we study the capacity of 30 peptones obtained by enzyme proteolysis of ten discarded fish species (hake, megrim, red scorpionfish, pouting, mackerel, gurnard, blue whiting, Atlantic horse mackerel, grenadier, and boarfish) to support the growth and metabolite production of four lactic acid bacteria (LAB) of probiotic and technological importance. Batch fermentations of Lactobacillus plantarum, L. brevis, L. casei, and Leuconostoc mesenteroides in most of the media formulated with fish peptones (87% of the cases) led to similar growths (quantified as dry-weight biomass and viable cells) and metabolites (mainly lactic acid) than in commercial control broth (MRS). Comparisons among cultures were performed by means of the parameters obtained from the mathematical fittings of experimental kinetics to the logistic equation. Modelling among experimental and predicted data from each bioproduction was generally accurate. A simple economic assessment demonstrated the profitability achieved when MRS is substituted by media formulated with fish discards: a 3-4-fold reduction of costs for LAB biomass, viable cells formation, and lactic and acetic acid production. Thus, these fish peptones are promising alternatives to the expensive commercial peptones as well as a possible solution to valorize discarded fish biomasses and by-products.

Comprehensive insights into microbial keratinases and their implication in various biotechnological and industrial sectors: A review

Enormous masses of keratinous wastes are annually accumulated in the environment as byproducts of poultry processing and agricultural wastes. Keratin is a recalcitrant fibrous protein, which represents the major constituent of various keratin-rich wastes, which released into the environment in the form of feathers, hair, wool, bristle, and hooves. Chemical treatment methods of these wastes resulted in developing many hazardous gases and toxins to the public health, in addition to the destruction of several amino acids. Accordingly, microbial keratinases have been drawing much interest as an eco-friendly approach to convert keratinous wastes into valuable products. Numerous keratinolytic microorganisms have been identified, which revealed the competence to hydrolyze keratins into peptides and amino acids. Several types of keratinolytic proteases have been produced that possess diverse biochemical characteristics, conferring them the versatility for implementing in multifarious applications such as detergents, leather and textile industries, animal feeding, and production of bio-fertilizers, in addition to medical and pharmaceutical treatments. This review article emphasizes the significance of keratinases and keratinase based-products via comprehensive insights into the keratin structure, diversity of keratinolytic microorganisms, and mechanisms of keratin hydrolysis. Furthermore, we discuss the biochemical properties of the produced keratinases and their feasible applications in diverse disciplines.

Application of lactic acid bacteria in green biorefineries

Lactic acid bacteria (LAB) have extensive industrial applications as producers of lactic acid, as probiotics, as biocontrol agents and as biopreservatives. LAB play a large role in food fermentation and in silage processes, where crops such as grass, legumes, cereals or corn are fermented into high-moisture feed that is storable and can be used to feed cattle, sheep or other ruminants. LAB also have great applications within green biorefineries, with simultaneous production of protein-rich feed for monogastric animals, silage or feed pellets for ruminants and production of lactic acid or specific amino acids. In green biorefineries, fresh or ensiled wet biomass is mechanically fractionated into green juice and solid residues (press cake), where the plant juice, for example, can be used for production of lactic acid using LAB. In a process named 'ENLAC', recovery of protein and chlorophyll from silage by simultaneous lactic acid fermentation and enzyme hydrolysis has been developed. Furthermore, a process for protein recovery was recently developed by applying a specific LAB starter culture to green juice from freshly harvested crops. This paper focuses on reviewing LAB for their applications within biorefining of 'green' crops such as clover, alfalfa, grasses and other green plant materials.

Evaluation of the potential use of a carp (Cyprinus carpio) skin gelatine hydrolysate as an antioxidant component

Gelatine hydrolysates are of increasing interest as potential ingredients used in various health-promoting functional foods. Cyprinus carpio skin gelatine hydrolysates can be a potential source of bioactive peptides with antioxidant properties. Therefore, the aim of this research was to evaluate the potential use of a carp skin gelatine hydrolysate with proven antioxidant properties as a bioactive compound in functional foods as well as its stability under various processing conditions. The analysis of the hydrolysate included its characterisation (ζ-potential, particle size distribution), solubility, antioxidant ability and stability (DPPH, FRAP, chelating properties) under various conditions (heating, pH and NaCl). Additionally, an analysis of residual environmental pollutants (heavy metals, dioxins and pesticides) was also conducted. The hydrolysate had high solubility over a range of pH values from 2 to 12 (84%-98%), and its antioxidant properties remained stable in low concentration NaCl solutions as well as after being heated at temperatures between 40 and 100 °C. The hydrolysate was not contaminated with heavy metals, dioxins or pesticides. According to our study, carp skin hydrolysates can be incorporated into food processing systems without significant loss of their antioxidant activities.

Production of Valuable Compounds and Bioactive Metabolites from By-Products of Fish Discards Using Chemical Processing, Enzymatic Hydrolysis, and Bacterial Fermentation

The objective of this report was to investigate the isolation and recovery of different biocompounds and bioproducts from wastes (skins and heads) that were obtained from five species discarded by fishing fleets (megrim, hake, boarfish, grenadier, and Atlantic horse mackerel). Based on chemical treatments, enzymatic hydrolysis, and bacterial fermentation, we have isolated and produced gelatinous solutions, oils that are rich in omega-3, fish protein hydrolysates (FPHs) with antioxidant and antihypertensive activities, and peptones. FPHs showed degrees of hydrolysis higher than 13%, with soluble protein concentrations greater than 27 g/L and in vitro digestibilities superior to 90%. Additionally, amino acids compositions were always valuable and bioactivities were, in some cases, remarkable. Peptones that were obtained from FPHs of skin and the heads were demonstrated to be a viable alternative to expensive commercial ones indicated for the production of biomass, lactic acid, and pediocin SA-1 from Pediococcus acidilactici.

Complete Genome Sequence of Actinobacillus succinogenes GXAS137, a Highly Efficient Producer of Succinic Acid

The bacterium Actinobacillus succinogenes GXAS137, an efficient producer of succinic acid, was isolated from bovine rumen in Nanning, Guangxi Province, China. Here, we present the 2.3-Mb genome assembly of this strain, which consists of 2,314,479 bp (G+C content of 44.89%) with a circular chromosome, 2,235 DNA coding sequences, 57 tRNAs, and 15 rRNAs.

Extracellular Enzyme Composition and Functional Characteristics of Aspergillus niger An-76 Induced by Food Processing Byproducts and Based on Integrated Functional Omics

Byproducts of food processing can be utilized for the production of high-value-added enzyme cocktails. In this study, we utilized integrated functional omics technology to analyze composition and functional characteristics of extracellular enzymes produced by Aspergillus niger grown on food processing byproducts. The results showed that oligosaccharides constituted by arabinose, xylose, and glucose in wheat bran were able to efficiently induce the production of extracellular enzymes of A. niger. Compared with other substrates, wheat bran was more effective at inducing the secretion of β-glucosidases from GH1 and GH3 families, as well as >50% of proteases from A1-family aspartic proteases. Compared with proteins induced by single wheat bran or soybean dregs, the protein yield induced by their mixture was doubled, and the time required to reach peak enzyme activity was shortened by 25%. This study provided a technical platform for the complex formulation of various substrates and functional analysis of extracellular enzymes.

Efficient production of succinic acid from duckweed (Landoltia punctata) hydrolysate by Actinobacillus succinogenes GXAS137

A novel process of enzyme pretreatment and semi-simultaneous saccharification and fermentation (SSSF) was developed in this work to improve succinic acid (SA) productivity from duckweed (Landoltia punctata) and achieve low viscosity. Viscosity (83.86%) was reduced by the pretreatment with combined enzymes at 50 °C for 2 h to a greater extent than that by single enzyme (26.19-71.75%). SSSF was an optimal combination with 65.31 g/L of SA content, which was remarkably higher than those obtained through conventional separate hydrolysis and fermentation (62.12 g/L) and simultaneous saccharification and fermentation (52.41 g/L). The combined approach was effective for SA production. Approximately 75.46 g/L of SA content with a yield of 82.87% and a productivity of 1.35 g/L/h was obtained after 56 h in a 2 L bioreactor. Further studies will focus on increasing the working scale of the proposed method.

Effect of oxygen mass transfer rate on the production of 2,3-butanediol from glucose and agro-industrial byproducts by Bacillus licheniformis ATCC9789

BACKGROUND

2,3-Butanediol (BD) is a largely used fossil-based platform chemical. The yield and productivity of bio-based BD fermentative production must be increased and cheaper substrates need to be identified, to make bio-based BD production more competitive. As BD bioproduction occurs under microaerobic conditions, a fine tuning and control of the oxygen transfer rate (OTR) is crucial to maximize BD yield and productivity. Very few studies on BD bioproduction focused on the use of non-pathogenic microorganisms and of byproducts as substrate. The goal of this work was to optimize BD bioproduction by the non-pathogenic strain Bacillus licheniformis ATCC9789 by (i) identifying the ranges of volumetric and biomass-specific OTR that maximize BD yield and productivity using standard sugar and protein sources, and (ii) performing a preliminary evaluation of the variation in process performances and cost resulting from the replacement of glucose with molasses, and beef extract/peptone with chicken meat and bone meal, a byproduct of the meat production industry.

RESULTS

OTR optimization with an expensive, standard medium containing glucose, beef extract and peptone revealed that OTRs in the 7-15 mmol/L/h range lead to an optimal BD yield (0.43 ± 0.03 g/g) and productivity (0.91 ± 0.05 g/L/h). The corresponding optimal range of biomass-specific OTR was equal to 1.4-7.9 [Formula: see text], whereas the respiratory quotient ranged from 1.8 to 2.5. The switch to an agro-industrial byproduct-based medium containing chicken meat and bone meal and molasses led to a 50% decrease in both BD yield and productivity. A preliminary economic analysis indicated that the use of the byproduct-based medium can reduce by about 45% the BD production cost.

CONCLUSIONS

A procedure for OTR optimization was developed and implemented, leading to the identification of a range of biomass-specific OTR and respiratory quotient to be used for the scale-up and control of BD bioproduction by Bacillus licheniformis. The switch to a byproduct-based medium led to a relevant decrease in BD production cost. Further research is needed to optimize the process of BD bioproduction from the tested byproduct-based medium.

Inhibitory substances production by Lactobacillus plantarum ST16Pa cultured in hydrolyzed cheese whey supplemented with soybean flour and their antimicrobial efficiency as biopreservatives on fresh chicken meat

Cheese whey, the main byproduct of the dairy industry, is one of the most worrisome types of industrial waste, not only because of its abundant annual global production but also because it is a notable source of environmental pollution. However, cheese whey can serve as a raw material for the production of biocomposites. In this context, in this study, we assayed the production of a bacteriocin-like inhibitory substance (BLIS) and lactate by culturing Lactobacillus plantarum ST16Pa in hydrolyzed fresh cheese whey. The process was improved by studying the enzymatic hydrolysis of cheese whey as well as its supplementation with soybean flour under microaerophilic or anaerobic conditions. Thus, the highest values of BLIS (7367.23 arbitrary units [AU]/mL) and lactate yield (Ylactate/lactose=1.39g/g) were achieved after addition of 10g/L soybean flour in microaerophilia. These conditions were successfully scaled up in a bioreactor because during complete anaerobiosis at 150rpm, L. plantarum ST16Pa attained considerable cell growth (3.14g/L), lactate concentration (14.33g/L), and BLIS activity (8082.56AU/mL). In addition, the cell-free supernatant resulting from this bioprocess showed high biopreservative efficiency in chicken breast fillets artificially contaminated with Enterococcus faecium 711 during 7days of refrigerated storage, thus indicating the potential use of this BLIS as a biopreservative in the food industry.

Leguminose green juice as an efficient nutrient for l(+)-lactic acid production

Lactic acid is one of the most important building blocks for the production of bioplastic. Many investigations have been conducted to reduce the lactic acid production costs. In this work, the focus was put on the application of legume pressed juice or green juice as nutrient source. The pressed juice was utilized directly without prior pre-treatment and sterilization. Using two different alfalfa green juices and a clover green juice from two different harvest years as sole nutrients, non-sterile fermentations were performed at 52°C and pH 6.0 with a thermotolerant strain Bacillus coagulans AT107. The results showed that alfalfa green juices generally were more suitable for high lactic acid production than clover green juices, presumably due to the higher nitrogen content. A final titer of 98.8g/L after 30h with l(+)-lactic acid purity of >99% was obtained.

Solid state fermentation of soybean waste and an up-flow column bioreactor for continuous production of camptothecine by an endophytic fungus Fusarium oxysporum

The potential of an endophytic fungus Fusarium oxysporum (NCIM 1383) to produce the anti-cancer pro-drug ‘camptothecine (CPT)’ by solid state fermentation (SSF) of agro-industrial by-products was investigated.