Kinetic Analysis of the Inhibition of in vitro Growth of Pathogenic Escherichia coli K88 and O138 by Lactobacillus Isolates from Porcine Intestine / 微生物学通报

Fermentation property and kinetic analysis of the inhibition of in vitro growth of pathogenic Escherichia coli K88, O138 by Lactobacillus intestinalis isolated from porcine intestine mucus were investi-gated. The results of fermentation showed that L1 result in a pH of 3.90 within 12 h and a large amount of lactic acid production, with the concentration of 104.08 mmol/L. Kinetic analysis of the antibacterial activity of L1 metabolic product toward K88, O138 showed that CFUS display strong antibacterial activity toward K88, O138; the antibacterial activity of L1 CFUS was higher than the lactic acid control samples and was mainly due to the production of lactic acid; K88, O138 had the tolerance property toward pH 4.5.

Effects of Mannan-oligosaccharide on the Growth of Lactobacillus Pure Culture and Co-culture / 微生物学通报

Effects of mannan-oligosaccharide (MOS) on the growth of Lactobacillus were investigated by pure culture of three swine originated Lactobacillus strains or co-culture with swine pathogenic E. coli. The pure culture results revealed that OD values and lactic acid concentration of three Lactobacillus strains in the MOS supplemented cultures were higher than those of the control group without MOS supplementation, a lower pH was observed for MOS supplement compared with that of the control group. The co-culture results showed that MOS were utilized by both Lactobacillus strains and swine pathogenic E. coli strain. But Lac-tobacillus grew faster than the latter. A significant increase in lactic acid concentration (P

Recombinant Probiotics for Prevention of Enteric Infections / 微生物学通报

Many microbial pathogens,including those responsible for major enteric infections,exploit oligosaccharides that are displayed on the surface of host cells as receptors for toxins and adhesins. Blocking crucial ligand receptor interactions is therefore a promising therapeutic strategy. One approach is to express molecular mimics of host receptors on the surface of harmless recombinant bacteria that can survive in the gut. These recombinant probiotics bind bacterial toxins in the gut lumen with very high avidity,thereby preventing disease.

Effects of Chinese Herbs on Gastrointestinal Bacteria / 微生物学通报

In China,Chinese herbs have been used to promote health status and prevent diseases for a long history.Most of the herbs are administered orally,then metabolized and absorbed in the gastrointestinal tract.After they enter gastrointestinal tract,the herbs meet gastrointestinal bacteria and exert effects on microbial community,resulting in affecting the health status of animals.This paper summarized the effects of Chinese herbs on gastrointestinal bacteria.

Partial Immunoactivies of Peptidoglycan from Lactic Acid Bacteria / 微生物学通报

Partial immunoactivities of peptidoglycan(PG)isolated from lactic acid bacteria were investigated.PG isolated from strain Z8 and Z17 of lactic acid bacteria respectively,had similar immunoactivities.The phagocytic function of M?(macrophage)increased markedly and serum lysozyme activity was significantly enhanced by injection of PG-extracts on mice.Investigation of immuno-enhancing effects of PG on vaccine of Newcastle disease in chickens showed that the hemagglutination inhibition levels of PG were higher than that of the control and the level was maintained for a longer time as compared to the control.

Lactic Acid Production and Tolerance Property of Lactic Acid Bacteria from Broiler Intestine / 微生物学通报

Lactic acid production of twelve strains of LAB isolated from broiler intestine and tolerance property of three strains were investigated. The results of lactic acid production showed that among all strains K6 exhibited the most rapid production during the first twelve hours, the seconds were K9 and C1; D17 exhibited the highest production of lactic acid by twenty-four hours, C1 exhibited the highest production of lactic acid by forty-eight hours. The pH values in three strains of K9、D17 and C1 culture showed the fast decline during the first twelve hours, with the final values significantly lower than those of other strains cultures. The results of tolerance property showed that the survival counts of C1could be detected when pH value was at 2 after three hours, but the survival counts of D17 and K9 could not be detected after one hour. When pH value was at 2.5 after three hours ,the survival counts of C1 declined from 10~ 8.2 /mL to 10~ 4.8 /mL, K9 from 10~ 8.2 /mL to 10~ 4.6 /mL, the survival counts of D17 could not be detected. 0.08% bile had few effects on the survival counts of three strains; when incubated in the medium with 0.40% bile, the survival counts of C1 declined from 10~ 8.4 /mL to 10~ 6.5 /mL,D17 from 10~ 10.3 /mL to 10~ 7.5 /mL, and K9 from 10~ 9.8 /mL to 10~ 7.7 /mL. When the group treated with 37℃ for 20 minutes was served as the control, the survival counts of C1 and K9 was not detected when treated with 80℃, but the survival counts of D17 were 10~ 4.9 /mL, when treatment with 65℃ the survival counts of C1 and K9 decreased significantly .

Probiotics-A New Immunomodulator / 微生物学通报

The relationship between probiotics and host intestinal immune system was reviewed. Then, as a new immunomodulator, the mechanisms and clinical uses of probiotics were discussed.

Lactic Acid Production and Antagonistic Effect of Lactic Acid Bacteria from Piglet Intestine / 微生物学通报

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.

Screening of Anaerobic Fungi and their Medium Modification for Xylanase Production / 微生物学通报

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