Effects Of Different Levels Of Tannins On Cellulose Degradation And Morphology Of Major Ruminal Cellulolytic Bacteria

In this study,major ruminal cellulolytic bacteria strains were isolated from the rumen of the Mongolia sheep.Bacterial physiological and biochemical characterization,16S rDNA sequence homology analysis were used for identification of isolated strains.The separated bacteria was cultiveed in culture medium with different concentration of tannins(0,100 ?g/mL,200 pg/mL,400 ?g/mL and 600 pg/mL)to evaluate the effect of tannins on growth feature,fermentation parameters in in vitro,morphology and cellulose degration feature.Select the concentration of tannins that have great affect on the growth and cellulose digestion of bacteria to add polyethylene glycol,which is twice concentration of tannins.Bacteria grow with and without tannins and with PEG were observed by scanning electron microscopy(SEM)and transmission electron microscopy(TEM)to research the influence of polyethylene glycol on removing effect of tannins on bacteria.The results showed as follows:1.Eight strains bacteria were identified as Ruminococcus flavefaciens numbered F1 and F2,and fibrobacter succinogenes FS1 and FS2,and Ruminococcus albus numbered A1 and A2,and Streptococcus S1 and S2.2.(1).The growth of cellulolytic bacteria was inhibited by tannins and the inhibition enhanced with the increasing concentration of tannins.(2).The gas production of F2,FS1,S1,S2 were significantly decreased in concentration of tannins between 100-200 ?g/mL(P<0.05),all bacteria gas production was inhibited in concentration between 400-600?g/mL(P<0.05).(3).The pH value of in vitro fermentation liquid increased as the increasing concentration of tannins.(4).NH3-N concentration of strains F1,F2,A1,A2,S1,S2 were significantly reduced by 100?g/mL of tannins(P<0.05),NH3-N concentration of 200?g/mL tannins group of F2,FS1,FS2,A2,S1,S2 was lower than control group(P<0.05).NH3-N concentration at 400-600 ?g/mL of tannins significantly lower than other groups(P<0.05).(5).400-600 ?g/mL of tannins seriously(P<0.05)declined BCP concentration of eight strains celllolytic bacteria,100?g/mL,200p?g/mL tannins significantly reduced BCP concentration of F1,F2,A1,A2,FS1,FS2,SI(P<0.05).(6).Addition of 100?g/mL tannins significantly(P<0.05)reduced acetic acid,propionic acid,butyric acid and total VFA of bacteria F1,F2,FS1,S1,S2 and A2,and reduced acetic acid and butyric acid and total VFA of bacteria FS2.At 200?g/mL tannins concentration,acetic acid,propionic acid,butyric acid and total VFA of FS1,FS2,A2,S1,S2 and propionic acid and butyric acid and total VFA of bacteria F1 clearly(P<0.05)reduced compared to control group.Addition 400?g/mL tannins significantly(P<0.05)reduced acetic acid,propionic acid,butyric acid and total VFA of strains FS1,A2,S1 S2.and reduced acetic acid,butyric acid and total VFA of F1,FS2.600?g/mL of tannins significantly(P<0.05)reduced acetic acid,propionic acid,butyric acid and total VFA concentration of strains FS1,A2,S1,S2,and reduced acetic acid,propionic acid and total VFA of F1,reduced propionic acid and butyric acid and total VFA of FS2.(7).100?g/mL and 200?g/mL tannins decreased(P<0.05)four types enzyme activity of FS1?S1?A2.All cellulase activity of all strains was reduced(P<0.05)by 400pg/mL,600?g/mL of tannins.(8).100?g/mL and 200?g/mL of tannins decreased cellulose digestion of bacteria F1,F2,FS2,A1,400?g/mL and 600 ?g/mL tannins significant decreased(P<0.05)all strains cellulose digestion.(9).Cells grown with tannins(400?g/mL)showed irregular shape and incomplete morphology and destruction of bacterial cell membranes.3.Addition of PEG increased growth of all strains comparaed to tannins group,increased the in vitro feimentation gas production,ammonia nitrogen concentration,BCP concentration,cellulose enzyme activity and cellulose digestion compared with tannins group.The in vitro fermentation gas production and cellulose enzyme activity and cellulose digestion was lower than control group.