Fermentation of Soybean Meal with Lactobacillus acidophilus Allows Greater Inclusion of Vegetable Protein in the Diet and Can Reduce Vibrionacea in the Intestine of the South American Catfish (Rhamdia quelen)

Nutritional attributes and microbial metagenomic profile during solid-state fermentation of soybean meal inoculated with Lactobacillus acidophilus under non-sterile conditions

BACKGROUND

Soybean meal (SBM) is used widely in animal feed but it contains anti-nutritional factors (ANFs) such as protease inhibitors - immunogenic proteins that limit its utilization. Fermentative processes could help to reduce these ANFs. The aim of this study was to evaluate the nutritional attributes, bacterial community dynamics, and microbial metagenomic profile during the solid-state fermentation of SBM using a strain of the bacterium Lactobacillus acidophilus with or without pre-autoclaving treatment.

RESULTS

Following fermentation, there was a reduction in the pH and a concurrent increase in the population of lactic acid bacteria. Fermentation also resulted in an increase in both crude and soluble protein levels. Trypsin inhibitor levels decreased after fermentation, particularly in fermented SBM that had not been pre-autoclaved, with an inactivation rate higher than 90%. Moreover, high-molecular-weight peptides (44-158 kDa), specifically some polypeptides from the soybean immunogen glycinin and β-conglycinin, underwent degradation during the fermentation process. Bacterial community analysis revealed the dominance of the Lactobacillus genus in all samples, regardless of the treatments applied. Metagenomic profiling identified L. acidophilus as the dominant species in inoculated SBM, irrespective of whether pre-autoclaving was conducted or not.

CONCLUSION

This study demonstrates the feasibility of solid-state fermentation with L. acidophilus under non-sterile conditions to inactivate trypsin inhibitor and increase protein concentration and hydrolysate immunogen proteins into low-molecular-weight peptides in SBM. Lactobacillus acidophilus inoculum also inhibited the growth of undesirable bacteria. This knowledge contributes to our understanding of the potential applications of solid-state fermentation with L. acidophilus in improving the nutritional quality of SBM. © 2024 Society of Chemical Industry.

Mechanism of action, benefits, and research gap in fermented soybean meal utilization as a high-quality protein source for livestock and poultry

Animal nutritionists have incessantly worked towards providing livestock with high-quality plant protein feed resources. Soybean meal (SBM) has been an essential and predominantly adopted vegetable protein source in livestock feeding for a long time; however, several SBM antinutrients could potentially impair the animal's performance and growth, limiting its use. Several processing methods have been employed to remove SBM antinutrients, including fermentation with fungal or bacterial microorganisms. According to the literature, fermentation, a traditional food processing method, could improve SBM's nutritional and functional properties, making it more suitable and beneficial to livestock. The current interest in health-promoting functional feed, which can enhance the growth of animals, improve their immune system, and promote physiological benefits more than conventional feed, coupled with the ban on the use of antimicrobial growth promoters, has caused a renewed interest in the use of fermented SBM (FSBM) in livestock diets. This review details the mechanism of SBM fermentation and its impacts on animal health and discusses the recent trend in the application and emerging advantages to livestock while shedding light on the research gap that needs to be critically addressed in future studies. FSBM appears to be a multifunctional high-quality plant protein source for animals. Besides removing soybean antinutrients, beneficial bioactive peptides and digestive enzymes are produced during fermentation, providing probiotics, antioxidants, and immunomodulatory effects. Critical aspects regarding FSBM feeding to animals remain uncharted, such as the duration of fermentation, the influence of feeding on digestive tissue development, choice of microbial strain, and possible environmental impact.

Substitution of fishmeal: Highlights of potential plant protein sources for aquaculture sustainability

High protein content, excellent amino acid profile, absence of anti-nutritional factors (ANFs), high digestibility and good palatability of fishmeal (FM), make it a major source of protein in aquaculture. Naturally derived FM is at risk due to an increase in its demand, unsustainable practices, and price. Thus, there is an urgent need to find affordable and suitable protein sources to replace FM. Plant protein sources are suitable due to their widespread availability and low cost. However, they contained certain ANFs, deficiency of some amino acids, low nutrient bioavailability and poor digestibility due to presence of starch and fiber. These unfavourable characteristics make them less suitable for feed as compared to FM. Thus, these potential challenges and limitations associated with various plant proteins have to be overcome by using different methods, i.e. enzymatic pretreatments, solvent extraction, heat treatments and fermentation, that are discussed briefly in this review. This review assessed the impacts of plant products on growth performance, body composition, flesh quality, changes in metabolic activities and immune response of fishes. To minimize the negative effects and to enhance nutritional value of plant products, beneficial functional additives such as citric acid, phytase and probiotics could be incorporated into the plant-based FM. Interestingly, these additives improve growth of fishes by increasing digestibility and nutrient utilization of plant based feeds. Overall, this review demonstrated that the substitution of fishmeal by plant protein sources is a plausible, technically-viable and practical option for sustainable aquaculture feed production.

Fermentation of Plant-Based Feeds with Lactobacillus acidophilus Improves the Survival and Intestinal Health of Juvenile Nile Tilapia (Oreochromis niloticus) Reared in a Biofloc System

This study evaluated the effect of fermentation with Lactobacillus acidophilus on the biochemical and nutritional compositions of a plant-based diet and its effects on the productive performance and intestinal health of juvenile Nile tilapia (Oreochromis niloticus) reared in a biofloc technology (BFT) system. The in vitro kinetics of feed fermentation were studied to determine the L. acidophilus growth and acidification curve through counting the colony-forming units (CFUs) mL-1 and measuring the pH. Physicochemical and bromatological analyses of the feed were also performed. Based on the microbial growth kinetics results, vegetable-based Nile tilapia feeds fermented for 6 (FPB6) and 18 (FPB18) h were evaluated for 60 days. Fermented diets were compared with a positive control diet containing fishmeal (CFM) and a negative control diet without animal protein (CPB). Fermentation with L. acidophilus increased lactic acid bacteria (LAB) count and the soluble protein concentration of the plant-based feed, as well as decreasing the pH (p < 0.05). FPB treatments improved fish survival compared with CPB (p < 0.05). Fermentation increased feed intake but worsened feed efficiency (p < 0.05). The use of fermented feeds increased the LAB count and reduced pathogenic bacteria both in the BFT system's water and in the animals' intestines (p < 0.05). Fermented plant-based feeds showed greater villi (FPB6; FPB18) and higher goblet cell (FPB6) counts relative to the non-fermented plant-based feed, which may indicate improved intestinal health. The results obtained in this study are promising and show the sustainable potential of using fermented plant-based feeds in fish feeding rather than animal protein and, in particular, fishmeal.

Wide-genome selection of lactic acid bacteria harboring genes that promote the elimination of antinutritional factors

Anti-nutritional factors (ANFs) substances in plant products, such as indigestible non-starchy polysaccharides (α-galactooligosaccharides, α-GOS), phytate, tannins, and alkaloids can impede the absorption of many critical nutrients and cause major physiological disorders. To enhance silage quality and its tolerance threshold for humans as well as other animals, ANFs must be reduced. This study aims to identify and compare the bacterial species/strains that are potential use for industrial fermentation and ANFs reduction. A pan-genome study of 351 bacterial genomes was performed, and binary data was processed to quantify the number of genes involved in the removal of ANFs. Among four pan-genomes analysis, all 37 tested Bacillus subtilis genomes had one phytate degradation gene, while 91 out of 150 Enterobacteriacae genomes harbor at least one genes (maximum three). Although, no gene encoding phytase detected in genomes of Lactobacillus and Pediococcus species, they have genes involving indirectly in metabolism of phytate-derivatives to produce Myo-inositol, an important compound in animal cells physiology. In contrast, genes related to production of lectin, tannase and saponin degrading enzyme did not include in genomes of B. subtilis and Pediococcus species. Our findings suggest a combination of bacterial species and/or unique strains in fermentation, for examples, two Lactobacillus strains (DSM 21115 and ATCC 14869) with B. subtilis SRCM103689, would maximize the efficiency in reducing the ANFs concentration. In conclusion, this study provides insights into bacterial genomes analysis for maximizing nutritional value in plant-based food. Further investigations of gene numbers and repertories correlated to metabolism of different ANFs will help clarifying the efficiency of time consuming and food qualities.

Isolation and characterization of a novel hydrolase-producing probiotic Bacillus licheniformis and its application in the fermentation of soybean meal

Soybean meal (SBM) is one of the most important sources of plant-based protein in the livestock and poultry industry. However, SBM contains anti-nutritional factors (ANFs) such as glycinin, β-conglycinin, trypsin inhibitor and phytic acid that can damage the intestinal health of animals, inevitably reducing growth performance. Fermentation using microorganisms with probiotic potential is a viable strategy to reduce ANFs and enhance the nutritional value of SBM. In this study, a novel potential probiotic Bacillus licheniformis (B4) with phytase, protease, cellulase and xylanase activity was isolated from camel feces. The ability of B4 to tolerate different pH, bile salts concentrations and temperatures were tested using metabolic activity assay. It was found that B4 can survive at pH 3.0, or 1.0% bile salts for 5 h, and displayed high proliferative activity when cultured at 50°C. Furthermore, B4 was capable of degrading glycinin, β-conglycinin and trypsin inhibitor which in turn resulted in significant increases of the degree of protein hydrolysis from 15.9% to 25.5% (p < 0.01) and crude protein from 44.8% to 54.3% (p < 0.001). After fermentation with B4 for 24 h, phytic acid in SBM was reduced by 73.3% (p < 0.001), the neutral detergent fiber (NDF) and the acid detergent fiber of the fermented SBM were significantly decreased by 38.40% (p < 0.001) and 30.20% (p < 0.05), compared to the unfermented SBM sample. Our results suggested that the effect of solid-state fermented SBM using this novel B. licheniformis (B4) strain, could significantly reduce phytic acid concentrations whilst improving the nutritional value of SBM, presenting itself as a promising alternative to phytase additives.

Fermented Soybean Meal (FSBM) in African Catfish (Clarias gariepinus) Diets: Effects on Growth Performance, Fish Gut Microbiota Analysis, Blood Haematology, and Liver Morphology

The study revealed the potential of fermented soybean meal (FSBM) as a fish meal (FM) replacement in African catfish (Clarias gariepinus) feed formulation. Five isonitrogenous diets (32% crude protein) were prepared with five different levels of FSBM as FM replacement, namely 0% FSBM (T1), 40% FSBM (T2), 50% FSBM (T3), 60% FSBM (T4), and 70% (T5). The experimental fish was given the formulated diet for eight consecutive weeks. At the end of the feeding trial, the fish were subjected to growth performance, blood parameters, blood chemical, liver histology, and gut microbiota assessment. The study findings demonstrated that the experimental fish that received the T2 diet exhibited significantly higher (p < 0.05) growth performance. Experimental fish that received diet T2 had significantly higher (p < 0.05) white blood cell (WBC) and significantly lower (p < 0.05) in terms of cholesterol (CHOL), albumin (ALB), globulin (GLOB), and total protein (TP). The replacement of FSBM to FM significantly affected liver morphology on the sinusoid, vacuole, nucleus, and erythrocytes. Gut microbiota composition analysis showed a significantly high abundance (p < 0.05) of Akkermansia muciniphila in the experimental fish that received the T2 diet. The gut microbiota indicates that the experimental fish is in a healthy condition. In conclusion, replacing 40% FSBM with FM in aquafeed could enhance C. gariepinus growth performance and health conditions.