Isolation and characterization of novel Bacillus strains with superior probiotic potential: comparative analysis and safety evaluation

Abstract

Despite the current use of some Bacillus spp. as probiotics, looking for and introducing new efficient and safe potential probiotic strains is one of the most important topics in both microbiology and food industry. This study aimed to isolate, identify, and evaluate the probiotic characteristics and safety of some Bacillus spp. from natural sources. Thirty-six spore-forming, Gram-positive, and catalase-positive Bacillus isolates were identified in 54 samples of soil, feces and dairy products. Bacterial identification was performed using 16S rDNA sequencing. To evaluate the probiotic potential of isolates, the resistance of bacterial cells to simulated gastrointestinal tract (GIT) conditions, the presence of enterotoxin genes, their susceptibility to antibiotics, antimicrobial and hemolytic activities and biochemical profiles were investigated. The results revealed that eight sporulating Bacillus spp. isolates fulfilled all tested probiotic criteria. They showed a high growth rate, non-hemolytic and lecithinase activity, and resistance to simulated GIT conditions. These strains exhibited broad-spectrum antibacterial activity against pathogenic bacteria. In addition, they did not exhibit antibacterial resistance to the 12 tested antibiotics. The results of this study suggest that these isolates can be considered as candidates for functional foods and as safe additives to improve diet quality.

Solid-State Fermentation Using Bacillus licheniformis-Driven Changes in Composition, Viability and In Vitro Protein Digestibility of Oilseed Cakes

“…For a functional probiotic-based feed to effectively exert its activity, the probiotic microorganisms must endure harsh or challenging environmental conditions from the GI tract, including low pH, high temperatures, elevated levels of bile salts, and nutrient deprivation [57]. Considering the resilience of Bacillus spores in withstanding gastrointestinalsimulated conditions as shown in this study, an intriguing question arises regarding their capacity to transition into vegetative states and sustain their life cycle and potentially colonizing the intestine.…”

Bacillus halotolerans attenuates inflammation induced by enterotoxigenic Escherichia coli infection in vivo and in vitro based on its metabolite soyasaponin I regulating the p105-Tpl2-ERK pathway

“…7–9 These bioactive substances play a crucial role as pharmaceuticals in alleviating human or animal ailments. 9 Bacillus stands out as one of the most representative bacterial groups, which can produce a variety of antibacterial substances through culture or fermentation, 10,11 including polypeptides, 8 bacteriocins, 10 fatty acids, 12 polyketones, 13 isocoumarins, 8 and soyasaponin (SoSa). 14 These compounds demonstrate diverse structures, a broad range of biological activities, including antibacterial, antiviral, and anticancer effects, 15 and play a beneficial role in disease resistance by either directly inhibiting or indirectly stimulating the host defense mechanism.…”