Notable fibrolytic enzyme production by Aspergillus spp. isolates from the gastrointestinal tract of beef cattle fed in lignified pastures.

Fungi have the ability to degrade vegetal cell wall carbohydrates, and their presence in the digestive tract of ruminants can minimize the effects of lignified forage on ruminal fermentation. Here, we evaluated enzyme production by Aspergillus spp. isolates from the digestive tracts of cattle grazed in tropical pastures during the dry season. Filamentous fungi were isolated from rumen and feces by culture in cellulose-based medium. Ninety fungal strains were isolated and identified by rDNA sequence analysis, microculture, or both. Aspergillus terreus was the most frequently isolated species, followed by Aspergillus fumigatus. The isolates were characterized with respect to their cellulolytic, xylanolytic, and lignolytic activity through qualitative evaluation in culture medium containing a specific corresponding carbon source. Carboxymethyl cellulase (CMCase) activity was quantified by the reducing sugar method. In the avicel and xilan degradation test, the enzyme activity (EA) at 48 h was significantly higher other periods (P < 0.05). Intra- and inter-specific differences in EA were verified, and high levels of phenoloxidases, which are crucial for lignin degradation, were observed in 28.9% of the isolates. Aspergillus terreus showed significantly higher EA for avicelase (3.96 ±1.77) and xylanase (3.13 ±.091) than the other Aspergillus species at 48 h of incubation. Isolates AT13 and AF69 showed the highest CMCase specific activity (54.84 and 33.03 U mg-1 protein, respectively). Selected Aspergillus spp. isolates produced remarkable levels of enzymes involved in vegetal cell wall degradation, suggesting their potential as antimicrobial additives or probiotics in ruminant diets.

Antimicrobial activity of Syagrus coronata (Martius) Beccari

This work aimed to evaluate the antimicrobial activity of aqueous and methanol extracts of leaves, inflorescences, nut-shell, liquid and solid endosperm nuts of Syagrus coronata against pathogenic bacteria and yeast. Screening was initially performed using the agar dilution method. The extracts regarded as bioactive underwent liquid-liquid partition for determination of their minimum inhibitory concentration and minimum bactericide concentration (MIC and MBC) and those of their respective fractions against the microorganisms inhibited in preliminary tests. Antimicrobial activity was observed only in inflorescences. The corresponding aqueous extract was effective against B. cereus and the three strains of S. aureus, and the corresponding MIC and MCB values were lower than those of dichloromethane, ethyl acetate and butanol fractions of the same extract. The methanol extract was effective against B. cereus, and the corresponding MIC and MBC values were higher than those of ethyl acetate and butanol fractions of the same extract.