Cellulolytic Bacillus Strain: Production Optimization Using Wheat Bran under Solid-State Fermentation and Investigation of Its Probiotic Potential

Abstract

Attention to the association of cellulolytic bacteria with probiotic potential as an additive in animal feeding has risen in the last decades. Such additive use in livestock feed is essential in improving animal health, growth, and production performances. This study was designed to identify probiotic characteristics and test the cellulolytic ability of Bacillus strains isolated from the dromedary gastrointestinal tract. Thus, thirty-two Bacillus strains were tested for their cellulolytic ability on cellulose Congo-red agar media. Among the isolates, only the strain D1B3 showed the largest degradation zone (2.4 cm) and was identified as Bacillus amyloliquefacians by 16S rRNA gene sequence analysis. Solid-state fermentation (SSF) retained this strain for cellulase and biomass production using wheat bran as a substrate. The fermentation was optimized through a central composite design, by exploring three factors: incubation temperature, moisture ratio, and pH. Biomass and cellulose enzyme activity were selected as responses and corresponding regression coefficients were calculated. The optimal parameters were: liquid-to-solid ratio (1.19%), pH buffer (6.2), and incubation temperature (36.99 °C) to obtain the highest level of biomass and cellulose enzyme activity reaching a value of 9.828 log CFU/g and 0.0144 g/L.min, respectively. The potentiality of Bacillus amyloliquefacians D1B3 as a probiotic was examined in vitro. It also showed antimicrobial activity against Pseudomonas aeruginosa 9027, Klebsiella pneumoniae, and Escherichia coli 10536. The isolate tolerates low pH and bile salt (0.3% Oxygall). The hydrophobicity and coaggregation abilities were 1.7% and 69.79%, respectively. The results indicated that Bacillus amyloliquefacians D1B3 could be a potential probiotic additive for improving in vitro fermentation of wheat bran and suggests the possibility of combining the probiotic attributes of this strain with its cellulolytic ability to enhance the rumen fermentation of animal feed.

Probiotics and Postbiotics as an Alternative to Antibiotics: An Emphasis on Pigs

“…A variety of commercial probiotics for swine are currently available in the market, and small doses of these additives are frequently used. One study revealed that probiotics typically accounted for USD 13.65 billion in 2019 and are estimated to increase by 6.1% in 2027, depending on the manufacturer and the product’s active components [ 151 ]. In commercial pig farming, higher growth performance and feed efficiency are likely to result in lower production costs.…”

Indigenous Bacteria Diversity of Fermetodege Based on Molecular Analysis The Next Generation Sequencing (NGS)

“…In the process of composting plant residues for compost production, many cellulolytic bacteria are also used [2]. Cellulolytic bacteria have been shown to be potential probiotics for ruminants [3]. Sheep with probiotic supplementary feed showed better biomass growth in all ages than sheep that were not supplemented with probiotics.…”

Optimization, gene cloning, expression, and molecular docking insights for enhanced cellulase enzyme production by Bacillus amyloliquefaciens strain elh1

“…Numerous factors can be adjusted to enhance enzyme productivity and yield, including media components such as carbon, nitrogen, mineral sources, additives, and inducers, as well as physical parameters like pH, aeration, and temperature. These factors play a crucial role in determining the cost of enzyme production, which is often considered a primary challenge in biotechnological processes [ 21 ]. Researchers typically use a one-variable-at-a-time (OVAT) approach to screen physical and chemical parameters.…”

“…The aim is to identify optimal conditions and understand the specific impact of each variable. However, this method is time-consuming and may overlook interactions between variables, leading to suboptimal results [ 21 , 22 ].…”