Bacillus Species as Direct-Fed Microbial Antibiotic Alternatives for Monogastric Production

Abstract

Antibiotic growth promoters have been utilized for long time at subtherapeutic levels as feed supplements in monogastric animal rations. Because of their side-effects such as antibiotic resistance, reduction of beneficial bacteria in the gut, and dysbiosis, it is necessary to look for non-therapeutic alternatives. Probiotics play an important role as the key substitutes to antibacterial agents due to their many beneficial effects on the monogastric animal host. For instance, enhancement of the gut microbiota balance can contribute to improvement of feed utilization efficiency, nutrients absorption, growth rate, and economic profitability of livestock. Probiotics are defined as “live microorganisms that, when administered in adequate amounts, confer a health benefit on the host.” They are available in diverse forms for use as feed supplements. Their utilization as feed additives assists in good digestion of feed ingredients and hence, making the nutrients available for promoting growth. Immunity can also be enhanced by supplementing probiotics to monogastrics diets. Moreover, probiotics can help in improving major meat quality traits and countering a variety of monogastric animals infectious diseases. A proper selection of the probiotic strains is required in order to confer optimal beneficial effects. The present review focuses on the general functional, safety, and technological screening criteria for selection of ideal Bacillus probiotics as feed supplements as well as their mechanism of action and beneficial effects on monogastric animals for improving production performance and health status. Supplementary Information The online version contains supplementary material available at 10.1007/s12602-022-09909-5.

Immunomodulatory and Antioxidant Properties of a Novel Potential Probiotic Bacillus clausii CSI08

“…Spore-forming bacteria of the genus Bacillus represent an ample and remarkably diverse group of microorganisms. Their capacity to produce a wide variety of secondary metabolites, such as antibiotics, enzymes, vitamins, and carotenoids, created a huge potential for use in pharmaceutical, agricultural, and industrial processes [ 49 , 50 , 51 ]. Bacillus strains have been recognized as safe and efficacious probiotics, offering, in addition to classic probiotic traits, notably high stability during processing and storage [ 52 ], as well as relatively low production costs [ 53 ].…”

Bacillus licheniformis–fermented products and enramycin differentially modulate microbiota and antibiotic resistome in the cecal digesta of broilers

“…The main antibacterial mechanisms of Bacillus spp. in the gut include competitive exclusion, competition for substrates and limiting resources, and antimicrobial substance synthesis ( Bahaddad et al, 2022 ). We previously demonstrated that the antimicrobial lipopeptides isolated from BLFPs exhibit antibacterial activity against Gram-positive and Gram-negative bacteria ( Horng et al, 2019 ).…”

“…Bacillus spp. have been proposed to inhibit gut pathogens through various mechanisms, such as competitive exclusion, competition for substrates and limiting resources, and production of antimicrobial substances ( Bahaddad et al, 2022 ). These findings indicate that enramycin and BLFPs exhibit distinct antibacterial mechanisms in the gut.…”

Inhibitory Effect of Bacillus licheniformis Strains Isolated from Canine Oral Cavity

“…Bacillus spp. are prolific in the production of antimicrobial substances which may give them a selective advantage over other bacterial species [ 51 ]. Levan is a fructan-type EPS produced from sucrose via extracellular levansucrases by many bacteria, including B. licheniformis , and its synthesis can occur both under aerobic and anaerobic conditions [ 52 , 53 ].…”