Selection of <Emphasis Type="Italic">Lactobacillus plantarum</Emphasis> TN627 as a new probiotic candidate based on <Emphasis Type="Italic">in vitro</Emphasis> functional properties

Nine lactobacilli previously selected for high antagonism against food borne bacterial pathogens were identified via 16S rRNA gene sequencing and screened for probiotic potential for use in poultry production. The lactobacilli were subjected to a subtractive in vitro analysis system using a certified probiotic as reference. This allowed for selection of a milk-derived Lactobacillus plantarum strain, termed TN627. This organic acid-producing bacterium was free of harmful enzymatic activity and sensitive to several antibiotics. It also showed good growth at pH 4 and in the presence of bile. L. plantarum TN627 also exhibited high efficacy of adhesion to chicken enterocytes, which correlated with detecting genes encoding the mucusbinding, adhesion-promoting proteins (Mub and MapA) and the adhesion-like factor EF-Tu, commonly involved in adherence of lactobacilli to mucosal surfaces. Taken together, our findings suggest that TN627 is a promising probiotic candidate with high potential for application as a supplement in the animal feed industry.     

Effects of Dietary Supplementation with Bacillus amyloliquefaciens US573 on Intestinal Morphology and Gut Microbiota of European Sea Bass

Probiotics and Antimicrobial Proteins - Probiotics or direct-fed microbials (DFM) have proven strong potential for improving aquaculture sustainability. This study aims to evaluate the effects of...     

Optimization of β-mannanase production by Bacillus subtilis US191 using economical agricultural substrates

The Bacillus subtilis US191 strain producing highly thermostable β-mannanase was previously selected as potential probiotic candidate for application as feed supplement in poultry industry. Initially, the level of extracellular β-mannanase production by this strain was 1.48 U ml⁻¹. To improve this enzyme titer, the present study was undertaken to optimize the fermentation conditions through experimental designs and valorization of agro-industrial byproducts. Using the Plackett–Burman design, in submerged fermentation, a set of 14 culture variables was evaluated in terms of their effects on β-mannanase production. Locust bean gum (LBG), soymeal, temperature, and inoculum size were subsequently optimized by response surface methodology using Box–Behnken design. Under optimized conditions (1 g L⁻¹ LBG, 8 g L⁻¹ soymeal, temperature of 30°C and inoculum size of 10¹⁰ CFU ml⁻¹), a 2.59-fold enhancement in β-mannanase titer was achieved. Next, to decrease the enzyme production cost, the effect of partial substitution of LBG (1 g L⁻¹) by agro-industrial byproducts was investigated, and a Taguchi design was applied. This allowed the attaining of a β-mannanase production level of 8.75 U ml⁻¹ in presence of 0.25 g L⁻¹ LBG, 5 g L⁻¹ of coffee residue powder, 5 g L⁻¹ of date seeds powder, and 5 g L⁻¹ of prickly pear seeds powder as mannans sources. Overall, a 5.91-fold improvement in β-mannanase production by B. subtilis US191 was achieved.