The Bacillus subtilis strain VTT E-68013 was chosen for purification and characterization of its excreted phytase. Purified enzyme had maximal phytase activity at pH 7 and 55°C. Isolated enzyme required calcium for its activity and/or stability and was readily inhibited by EDTA. The enzyme proved to be highly specific since, of the substrates tested, only phytate, ADP, and ATP were hydrolyzed (100, 75, and 50% of the relative activity, respectively). The phytase gene (phyC) was cloned from the B. subtilis VTT E-68013 genomic library. The deduced amino acid sequence (383 residues) showed no homology to the sequences of other phytases nor to those of any known phosphatases. PhyC did not have the conserved RHGXRXP sequence found in the active site of known phytases, and therefore PhyC appears not to be a member of the phytase subfamily of histidine acid phosphatases but a novel enzyme having phytase activity. Due to its pH profile and optimum, it could be an interesting candidate for feed applications.

A DNA-based, direct method for initial characterization of the total bacterial community in ileum and cecum of the chicken gastrointestinal (GI) tract was developed. The efficiencies of bacterial extraction and lysis were >95 and >99%, respectively, and therefore the DNA recovered should accurately reflect the bacterial communities of the ileal and cecal digesta. Total bacterial DNA samples were fractionated according to their percent G+C content. The profiles reflecting the composition of the bacterial community were reproducible within each compartment, but different between the compartments of the GI tract. This approach is independent of the culturability of the bacteria in the consortium and can be used to improve our understanding of how diet and other variables modulate the microbial communities of the GI tracts of animals.

This review focuses upon poultry. Sections consider the physicochemical environment of the digestive tract, microbial responses to exogenous enzymes, indirect interactions between host and microflora mediated by enzymes, a microbial modulators with the potential to interact with a response to enzymes.

Two similar Gram-positive rods were isolated from 10 "6 dilutions of ruminal fluid from a sheep receiving a mixed grass hay/concentrate diet, using a medium containing pancreatic casein hydrolysate as sole source of carbon and energy. The isolates did not ferment sugars, but grew on pyruvate or trypticase, forming caproate as the main fermentation product and valerate to a lesser extent. Acetate and propionate were utilized. One of these strains, I-6 T , was selected for further study. Strain I-6 T was a non-motile coccal rod, 1?260?4 mm, with a Gram-positive cell wall ultrastructure and a G+C content of 56?8 mol%. No spores were visible, and strain I-6 T did not survive heating at 80˚C for 10 min. Its rate of NH 3 production was 375 nmol (mg protein) "1 min "1 , placing it in the 'ammonia-hyperproducing' (or HAP) group of ruminal bacteria. 16S rDNA sequence analysis (1296 bases) indicated that it represents a novel species within the 'low-G+C' Grampositive group, for which the name Eubacterium pyruvativorans sp. nov. is proposed. Among cultivated bacteria, strain I-6 T was most closely related (89 % identity) to other asaccharolytic Eubacterium isolates from the mouth and the rumen. It was 98 % identical to uncultured bacterial sequences amplified by others from ruminal digesta.

Two independent studies were performed, each with a 3 × 2 factorial arrangement to compare the response in broilers and turkeys to phytase and xylanase supplementation on cecal fermentation and microbial populations. For both studies, 960 Ross 308 and 960 BUT 10 (1-day-old) were allocated to 1 of 6 experimental treatments: (1) control diet, containing the standard dose (100 g/ton) of phytase ( STD-Xyl ); (2) the control diet with 100 g/ton of xylanase ( STD + Xyl ); (3) the control diet supplemented on top with 2 fold the standard dose of phytase (200 g/ton), also referred as superdosing ( SD-Xyl ); (4) the superdosed diet with 100 g/ton of xylanase ( SD + Xyl ); (5) the control diet supplemented with 5-fold the standard dose of phytase (500 g/ton), also referred as megadosing ( MD-Xyl ); and (6) the megadosed diet with 100 g/ton of xylanase ( MD + Xyl ). Each treatment had 8 replicates of 20 animals. Broiler and turkey diets, based on wheat, soybean meal, rapeseed, and barley, and water were available ad libitum. On day 28, the cecal contents from 5 birds per pen were collected. The profile of short-chain fatty acids ( SCFA ) and microbiome structure (by % guanidine and cytosine [ G + C ] method) were analyzed. Selected % G + C fractions were used for 16S rDNA sequencing for the identification of bacteria. No treatment effects were noted on SCFA concentrations in either broilers or turkeys. Broilers fed MD diets had greater proportions of unclassified Clostridiales , Mollicutes (RF9) and Faecalibacterium . Xylanase supplementation in broilers resulted in lower proportions of Lactobacillus but increased Mollicutes (RF9), unclassified Ruminococcus , unclassified Clostridiales , and Bifidobacterium . The microbiome in turkeys was unaffected by phytase supplementation, but xylanase supplementation increased the proportions of Lachnospiraceae ( Incertae sedis ), Lactobacillus , and Bifidobacterium . Supplementation of turkey diets with increasing doses of phytase did not affect the cecal microbiota in contrast to what was observed in broilers. In contrast, xylanase supplementation in both species led to significant changes in the microbial populations, suggesting a positive influence through the provision of oligosaccharides.