Association of Bacillus subtilis and Bacillus amyloliquefaciens: minimizes the adverse effects of necrotic enteritis in the gastrointestinal tract and improves zootechnical performance in broiler chickens.

This study aimed to evaluate the efficiency and capacity of the probiotic composed of Bacillus subtilis and Bacillus amyloliquefaciens, in improving the zootechnical performance of broiler chickens challenged with Eimeria spp. and Clostridium perfringens. The broilers were distributed in a completely randomized design in poultry isolators (12 birds each), resulting in 3 treatments: T1 (control, no challenge and no Bacillus in diet), T2 (challenged with Eimeria spp., followed by Clostridium perfringens infection and no Bacillus in the diet), and T3 (challenged with Eimeria spp., Clostridium perfringens and treated with Bacillus subtilis and Bacillus amyloliquefaciens). They were evaluated for a period of 29 d, divided into preinitial (1-7 d of age), initial (8-21 d), and growth (22-29 d) phases. Assessments of body weight, weight gain, feed consumption, and feed conversion were conducted, along with the classification of the scores and optical microscopy of the tract gastrointestinal. The animals challenged and treated with the probiotic containing Bacillus spp. showed improved indicators of zootechnical performance. Additionally, the animals challenged and treated (T3) had a better score for intestinal lesions compared to the other treatment groups. Therefore, the probiotic consisting of Bacillus subtilis and Bacillus amyloliquefaciens could be considered an effective option for disease prevention and improving the zootechnical performance of broiler chickens.

Genomic Sequence of the Yeast Kluyveromyces marxianus CCT 7735 (UFV-3), a Highly Lactose-Fermenting Yeast Isolated from the Brazilian Dairy Industry.

Here, we present the draft genome sequence of Kluyveromyces marxianus CCT 7735 (UFV-3), including the eight chromosomes and the mitochondrial genomic sequences.

Construction of a Kluyveromyces lactis ku80⁻ host strain for recombinant protein production: extracellular secretion of pectin lyase and a streptavidin-pectin lyase chimera.

In several organisms used for recombinant protein production, integration of the expression cassette into the genome depends on site-specific recombination. In general, the yeast Kluyveromyces lactis shows low gene-targeting efficiency. In this work, two K. lactis ku80⁻ strains defective in the non-homologous end-joining pathway (NHEJ) were constructed using a split-marker strategy and tested as hosts for heterologous gene expression. The NHEJ pathway mediates random integration of exogenous DNA into the genome, and its function depends on the KU80 gene. KU80-defective mutants were constructed using a split-marker strategy. The vectors pKLAC1/Plg1 and pKLAC1/cStpPlg1 were used to evaluate the recovered mutants as hosts for expression of pectin lyase (PNL) and the fusion protein streptavidin-PNL, respectively. The transformation efficiency of the ku80⁻ mutants was higher than the respective parental strains (HP108 and JA6). In addition, PNL secretion was detected by PNL assay in both of the K. lactis ku80⁻ strains. In HP108ku80⁻/cStpPlg1 and JA6ku80⁻/Plg1 cultures, the PNL extracellular specific activity was 551.48 (±38.66) and 369.04 (±66.33) U/mg protein. This study shows that disruption of the KU80 gene is an effective strategy to increase the efficiency of homologous recombination with pKLAC1 vectors and the production and secretion of recombinant proteins in K. lactis transformants.