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.

Characterization of fungi from ruminal fluid of beef cattle with different ages and raised in tropical lignified pastures.

The objective of this study was to evaluate the aerobic rumen mycobiota from three age groups of Nelore beef cattle reared extensively on lignified pasture. The experiment was randomized and sampled 50 steers, 50 cows, and 50 calves grazed on Brachiaria spp. pasture during the dry season. Rumen fluid in all animals was aromatic, slightly viscous, and greenish-brown in color. Microscopic examination revealed monocentric and polycentric anaerobic fungi in similar proportions (P > 0.05) in the rumen fluid of cows and steers. However, these microorganisms were not identified in any of the samples from calves. In culture exams, aerobic filamentous population was significantly higher for rumen fluid of cows compared to the other two groups. Microculture and rDNA sequence analyses showed Aspergillus spp. as the most frequent aerobic fungus among the isolates from the three bovine groups evaluated. Biochemical profiles were determined by the growth level of yeast isolates with 44 nutrient sources. Ten different yeast profiles were obtained, and yeast isolates from cow ruminal fluid showed ability to catabolize greater diversity of carbon and nitrogen sources. The differences in the fungal populations observed in this study could be explained by microbial and physiological interactions existing in the ruminal ecosystem of each age bovine group. The present study showed the fungal population of the rumen related with differences among age of cattle raised in lignified pastures. Metabolic capabilities of mycelial fungi or yeast identified in this study may be employed in new probiotics or microbial additives for different bovine categories.

Análise da contaminação parasitária em compostos orgânicos produzidos com biossólidos de esgoto doméstico e resíduos agropecuários / Analysis of parasitological contamination in organic composts with sewage sludge and agricultural residues

Este estudo avaliou a contaminação por ovos de helmintos, cistos e oocistos de protozoários em compostos orgânicos utilizando lodo de esgoto doméstico e resíduos agropecuários. Foram realizadas análises parasitológicas em amostras de 25 diferentes compostos orgânicos, antes e após tratamento térmico a 60°C durante 12 horas. Os resultados demonstraram elevada contaminação parasitária em todos os compostos analisados antes do tratamento e a não redução dessa contaminação após o tratamento térmico. A identificação das larvas obtidas em coproculturas antes e após o tratamento térmico dos compostos indicou que os gêneros mais freqüentemente observados foram Cooperia e Trichostrongylus, que são nematóides gastrintestinais de ruminantes. Estes resultados demonstram que ovos de helmintos podem permanecer viáveis mesmo após o processo de compostagem e o tratamento térmico. Os compostos produzidos com lodo de esgoto doméstico e resíduo agropecuários, utilizando esses processos de tratamentos, podem constituir riscos de contaminação para humanos e animais.

This research aimed at evaluating the cysts, oocysts and eggs contamination before and after thermal treatment of 60°C for 12 hours, in 25 different organic composts produced with biosolids from domestic waste-water treatment and animal and agricultural residues. The results showed high parasitological contamination for all organic composts before the treatment and these contaminations were not reduced after thermic treatment. The larva identification in coprocultures before and after thermic treatment showed Cooperia spp. and Trichostrongylus spp. were the most prevalent nematodes. These results demonstrated that helmintus’ eggs can remain viable even after the composing and thermic treatment. The obtained composition with sewage sludge and agricultural residues through these treatment processes can establish contamination risks for humans and animals.