RESUMO
Lactic acid production and antagonistic property of five strains of LAB isolated from piglet intestine were investigated. The results showed that among all strains L5 exhibited the most rapid production and highest amount of lactic acid in the culture. Consequently, the pH in L5 culture showed the fast decline, with the final value significantly lower than those of other cultures. Strain L1 showed the least production of lactic acid and highest pH among all strains. Culture supernatants of the five strains showed different degrees of antagonistic effect against pathogenic E. coli K88, K99, 987P, O141, E1, and S. aureus. When taking out the effect of the acid, the culture supernatants still showed 22%～53% inhibitory effect, suggesting that the bacteria produced other inhibitory substances apart from lactic acid. The inhibitory effect of the culture supernatant was above 92% after heat treatment and above 85% when treated with proteases.
RESUMO
Twelve anaerobic fungal strains isolated from rumen and faeces of ruminants were screened for xylanase prodution. Isolate A4 strain identified as Neocallimastix had the highest xylanase activity among all isolates. With rice straw, corn straw , peanut straw and filter paper as fermentation substrates, the activities of xylanase by A4 were14.31 U/mL, 11.39 U/mL, 6.99 U/mL, 13.38 U/mL, respectively. The effect of cell-free rumen fluid and yeast extract on xylanase production was tested. The results showed that the concentration level of cell-free rumen fluid had no significant effect on xylanase production. However as yeast extract concentration decreased from 1.0 g/L to 0,5 g/L , the enzyme activity decreased significantly ( P