Isolation and Characterization of Probiotic Bacillus subtilis MKHJ 1-1 Possessing L-Asparaginase Activity

Effects of Saccharomyces cerevisiae and Bacillus subtilis on in vitro fermentation in the rumen of Hu sheep

BACKGROUND

The demand for animal products is increasing in developing countries due to population growth. However, livestock production contributes significantly to global warming, accounting for 25%. Probiotics can help improve livestock efficiency by enhancing gut microbes and fat metabolism. They can modify rumen populations, enhance fermentation, reduce methane emissions and improve feed digestion. In this study, the goal was to determine the most effective method of reducing methane emissions in the rumen of sheep in vitro by adding different concentrations of Saccharomyces cerevisiae and Bacillus subtilis.

RESULTS

Adding 8 × 106 CFU g-1 S. cerevisiae during fermentation reduced pH levels after 48 h. This also increased the concentrations of NH3-N, microbial protein and total gas production. At the same time, it decreased methane emissions. Furthermore, adding 20 × 106 CFU g-1 B. subtilis to the mixture increased total gas production (TGP) and methane production, with the highest production observed after 48 h. However, it did not affect pH levels after 48 h.

CONCLUSION

It can be concluded that S. cerevisiae had significantly increased microbial protein and NH3-N concentrations after fermentation without altering pH. Additionally, the addition of S. cerevisiae enhanced TGP and reduced methane emissions. It is worth noting that TGP increased because B. subtilis was added at a concentration of 20 × 106 CFU g-1, with no significant differences between concentrations. Therefore, we recommend adding S. cerevisiae and B. subtilis to the diet at doses of 8 and 20 × 106 CFU g-1, as it resulted in higher TGP and reduced methane emissions. © 2024 Society of Chemical Industry.

Isolation, Identification, and Characterization of L-asparaginase-Producing Human Commensal Bacterial Strains: A Promising Next-Gen Probiotics

L-asparaginase is an FDA-approved drug for treating blood cancer, but its inherent antigenicity and L-glutaminase activity are associated with hypersensitivity and organ toxicity. Extracellularly produced glutaminase-free L-asparaginase from human commensal bacteria may be a good alternative to reduce the side effects of therapeutic L-asparaginase. Here, we report the isolation and characterization of fourteen L-asparaginase-producing bacterial strains belonging to the genera Acinetobacter, Escherichia, Klebsiella, and Pseudomonas from human stool and saliva samples. To the best of our knowledge, this is the first report of L-asparaginase-producing human commensal bacterial strains isolated from healthy individuals. L-asparaginase produced by fecal and salivary isolates exhibited significantly higher activity (3.64 to 16.96 U/ml) toward L-asparagine than L-glutamine. Interestingly, L-asparaginase from fecal isolates, Escherichia coli strains 3F1 and 3F2 and salivary isolate Klebsiella pneumoniae 3S3, exhibited no L-glutaminase activity. These isolates were also sensitive to all tested antibiotics. Additionally, these three isolates demonstrated tolerance to pH 3.0 (≥ 88% survival) and 0.3% bile (≥ 95% survival), indicating their potential as probiotics. Among these isolates, L-asparaginase from the highest-producing K. pneumoniae 3S3 strain was found to be a homodimer, with native and subunit molecular weights of 110 kDa and 55 kDa, respectively. The purified enzyme can be further explored for its antitumor and immunomodulatory properties. Overall, future research can be expanded to include the use of a pool of human commensal bacteria as genuine and alternative sources of L-asparaginase for effective cancer treatments and cutting-edge next-generation probiotics.

Extracellular nanovesicles produced by Bacillus licheniformis: A potential anticancer agent for breast and lung cancer

Cancer is a major public burden and leading cause of death worldwide; furthermore, it is a significant barrier to increasing life expectancy in most countries of the world. Among various types of cancers, breast and lung cancers lead to significant mortality in both males and females annually. Bacteria-derived products have been explored for their use in cancer therapy. Although bacteria contain significant amounts of anticancer substances, attenuated bacteria may still pose a potential risk for infection owing to the variety of immunomodulatory molecules present in the parental bacteria; therefore, non-cellular bacterial extracellular vesicles (BEVs), which are naturally non-replicating, safer, and are considered to be potential anticancer agents, are preferred for cancer therapy. Gram-positive bacteria actively secrete cytoplasmic membrane vesicles that are spherical and vary between 10 and 400 nm in size. However, no studies have considered cytoplasmic membrane vesicles derived from Bacillus licheniformisin cancer treatment. In this study, we investigated the potential use of B. licheniformis extracellular nanovesicles (BENVs) as therapeutic agents to treat cancer. Purified BENVs from the culture supernatant of B. licheniformis using ultracentrifugation and ExoQuick were characterized using a series of analytical techniques. Human breast cancer cells (MDA-MB-231) and lung cancer cells (A549) were treated with different concentrations of purified BENVs, which inhibited the cell viability and proliferation, and increased cytotoxicity in a dose-dependent manner. To elucidate the mechanism underlying the anticancer activity of BENVs, the oxidative stress markers such as reactive oxygen species (ROS) and glutathione (GSH) levels were measured. The ROS levels were significantly higher in BENV-treated cells, whereas the GSH levels were markedly reduced. Cells treated with BENVs, doxorubicin (DOX), or a combination of BENVs and DOX showed significantly increased expression of p53, p21, caspase-9/3, and Bax, and concomitantly decreased expression of Bcl-2. The combination of BENVs and doxorubicin enhanced mitochondrial dysfunction, DNA damage, and apoptosis. To our knowledge, this is the first study to determine the anticancer properties of BENVs derived from industrially significant probacteria on breast and lung cancer cells.

Production of glutathione from probiotic Bacillus amyloliquefaciens KMH10 using banana peel extract

Glutathione, a tri-peptide (glutamate-cysteine-glycine) with the thiol group (-SH), is most efficient antioxidative agent in eukaryotic cells. The present study aimed to isolate an efficient probiotic bacterium having the potential to produce glutathione. The isolated strain Bacillus amyloliquefaciens KMH10 showed antioxidative activity (77.7 ± 2.56) and several other essential probiotic attributes. Banana peel, a waste of banana fruit, is chiefly composed of hemicellulose with various minerals and amino acids. A consortium of lignocellulolytic enzyme was used for the saccharifying banana peel to produce 65.71 g/L sugar to support the optimal glutathione production of 181 ± 4.56 mg/L; i.e., 1.6 folds higher than the control. So, the studied probiotic bacteria could be an effective resource for glutathione; therefore, the stain could be used as natural therapeutics for the prevention/treatment of different inflammation-related gastric ailments and as an effective producer of glutathione using valorized banana waste that has excellent industrial relevance.

An Assessment of the Lactic Acid-Producing Potential of Bacterial Strains Isolated from Food Waste

Lactic acid (LA) is widely used in many industries as a crucial starting material in food products, bio-based materials, and biodegradable polymers. The goals of this research were to isolate LA bacteria from food wastes, assess their potential for LA production, and study their growth characteristics. In this study, six bacterial strains were isolated from food waste and identified using 16S rRNA gene sequencing; namely, Weissella viridescens WJ39, Leuconostoc lactis YS33, Leuconostoc citreum KD42, Leuconostoc mesenteroides VN60, Macrococcus caseolyticus FCI29, and Weissella confusa RG41. W. viridescens WJ39 showed the highest potential for lactic acid production (17.56 g L−1day−1), and the lowest potential was found in L. lactis YS33 (14.09 g L−1day−1). There were significant differences (p < 0.05) in the LA production rates among Weissella spp., Leuconostoc spp., and Macrococcus spp. Moreover, dramatic differences in growth rate were observed among the six strains. W. viridescens WJ39 exhibited the highest growth rate (0.80 h−1), while M. caseolyticus FCI29 exhibited the lowest growth rate (0.57 h−1). W. viridescens WJ39 also exhibited lactic acid production (at a rate around 2 g L−1day−1) in a lab incubation experiment with food waste as a nutrient source. The draft genome of W. viridescens WJ39 with 16 contigs was constructed with an N50 of 215217 bp. The genome size was approximately 1.54 Mb, with a GC content of 41%. A hicD gene, known to catalyze the conversion of pyruvate to D-lactate, was discovered in the genome. This study illustrated the potential for the production of lactic acid from food waste with lactic acid bacteria.

Bacillus licheniformis and Bacillus subtilis, Probiotics That Induce the Formation of Macrophage Extracellular Traps

Probiotics are considered living microorganisms that help preserve the health of the host who uses them. Bacillus are a genus of Gram-positive bacteria used as probiotics for animal and human consumption. They are currently distributed in various commercial forms. Two of the species used as probiotics are B. licheniformis and B. subtilis. Macrophages are central cells in the immune response, being fundamental in the elimination of microbial pathogens, for which they use various mechanisms, including the formation of extracellular traps (METs). There have been very few studies carried out on the participation of macrophages in response to the interaction of probiotics of the genus Bacillus with the host. In this work, we used macrophages from the J774A mouse cell line.1, and we found that they are susceptible to infection by the two Bacillus species. However, both species were eliminated as the infection progressed. Using confocal microscopy, we identified the formation of METs from the first hours of infection, which were characterized by the presence of myeloperoxidase (MPO) and citrullinated histone (Hit3Cit). Quantitative data on extracellular DNA release were also obtained; release was observed starting in the first hour of infection. The induction of METs by B. licheniformis caused a significant decrease in the colony-forming units (CFU) of Staphylococcus aureus. The induction of METS by bacteria of the Bacillus genus is a mechanism that participates in controlling the probiotic and potentially pathogenic bacteria such as S. aureus. The induction of METs to control pathogens may be a novel mechanism that could explain the beneficial effects of probiotics of the genus Bacillus.