Enhanced meat chicken productivity in response to the probiotic Bacillus amyloliquefaciens H57 is associated with the enrichment of microbial amino acid and vitamin biosynthesis pathways.

AIMS: Sub-therapeutic use of antibiotics as a growth promoter in animal diets has either been banned or voluntarily withdrawn from use in many countries to help curb the emergence of antibiotic-resistant pathogens. Probiotics may be an alternative to antibiotics as a growth promoter. We investigated the effects of a novel probiotic strain, Bacillus amyloliquefaciens H57 (H57) on the performance and microbiome-associated metabolic potential. METHODS AND RESULTS: Broiler chickens were fed either sorghum- or wheat-based diets supplemented with the probiotic H57. The growth rate, feed intake, and feed conversion in supplemented birds were compared with those in non-supplemented control. Caecal microbial metabolic functions were studied with shotgun metagenomic sequencing. H57 supplementation significantly increased the growth rate and daily feed intake of meat chickens relative to the non-supplemented controls without any effect on feed conversion ratio. In addition, relative to the non-supplemented controls, gene-centric metagenomics revealed that H57 significantly altered the functional capacity of the caecal microbiome, with amino acid and vitamin synthesis pathways being positively associated with H57 supplementation. CONCLUSIONS: Bacillus amyloliquefaciens H57 improves the performance of meat chickens or broilers and significantly modifies the functional potential of their caecal microbiomes, with enhanced potential capacity for amino acid and vitamin biosynthesis.

Toxic effects of low concentrations of Cu on nodulation of cowpea (Vigna unguiculata).

Although Cu is phytotoxic at Cu(2+) activities as low as 1-2 microM, the effect of Cu(2+) on the nodulation of legumes has received little attention. The effect of Cu(2+) on nodulation of cowpea (Vigna unguiculata (L.) Walp. cv. Caloona) was examined in a dilute solution culture system utilising a cation exchange resin to buffer solution Cu(2+). The nodulation process was more sensitive to increasing Cu(2+) activities than both shoot and root growth; whilst a Cu(2+) activity of 1.0 microM corresponded to a 10% reduction in the relative yield of the shoots and roots, a Cu(2+) activity of 0.2 microM corresponded to a 10% reduction in nodulation. This reduction in nodulation with increasing Cu(2+) activity was associated with an inhibition of root hair formation in treatments containing > or =0.77 microM Cu(2+), rather than to a reduction in the size of the Rhizobium population.