| Agricultural biomass resources are extremely abundant and renewable biofuels,chemical raw materials and feed sources in China.However,the complexity of the cell wall polysaccharide composition,the diversity of synthetase system and the heterogeneity of the supramolecular structure determines that straw is difficult to be effectively utilized by livestock and poultry which causes great waste.Anaerobic fungi are important fiber-degrading functional microorganisms in the herbivores’ digestive tract.The present study used the Hungate roll tube technique to isolate and identify fungus with high plant cell wall degrading enzymes activity from the rumen of Xinong Saanen dairy goat.Studying the application of fungi on corn silage could evaluate the efficiency and potential of degradation of plant cell plant wall by rumen anaerobic fungi,and could provide a theoretical basis and technical support for the utilization of rumen microorganism resource and the plant cell wall degrading enzymes in feed industry.Isolation and Identification of Rumen Fungi with High Plant Cell Wall Degrading Enzymes Activity and Its Enzymological CharacterizationThe purpose of this research was to screen anaerobic rumen fungi with high activity plant cell wall degrading enzymes for practical applications to improve the utilization of roughage.12 anaerobic fungi strains were isolated from Xinong Saanen dairy goat using the Hungate roll tube technique.Based on morphological characteristics and sequence analysis of internal transcribed spacer region and 28 S r DNA D1/D2 region,the fungi strains were identified.Meanwhile,activities of xylanase,carboxymethyl cellulose(CMCase),avicelase,acetyl esterase(AE)and β-glucanase of 12 fungi cultures were assayed,and the enzymatic characteristics of xylanase and aceteyl esterases produced by Piromyces sp.CN6 were also analysed.The results showed that,12 anaerobic fungi strains were belonged to Piromyces and they were named Piromyces sp.CN1~Piromyces sp.CN12,respectively.The xylanase,CMCase and AE activities of Piromyces sp.CN6 were 1655.3,93.4and 152.8 mU,which were significantly higher than other fungi strains(P<0.05).The avicelase activity of Piromyces sp.CN3 was the highest,but showed no difference with Piromyces sp.CN6(P>0.05).There was no significant difference on β-glucanase activityproduced by fungi strains(P>0.05).And the xylanase activities had extremely significant positive correlation with CMCase and AE activities(P<0.01),and the xylanase activities also had significant positive with avicelase activity(P<0.05).The optimum temperature of xylanaseactivity was 50℃,and the optimum pH was 5.0.The xylanase was stable at 40℃ and pH 5.0~8.0.K+,Ca2+,Co2+ had active effects on the enzyme whereas Zn2+,Cu2+,Mg2+,Fe2+ and Mn2+ had inhibitory effect on it.The AE activity preformed optimally at 50℃ and pH 9.0.And it was stable at 40℃ and pH 5.0~10.0.The AE activity could be promoted by Mg2+,K+ and Ca2+,and inhibited by Zn2+,Fe2+,Co2+ and Mn2+.12 anaerobic fungi strains were isolated from Xinong Saanen dairy goat,Piromyces sp.CN6 showed the highest plant cell wall degrading enzymes activity,and xylanse and AE activity had high pH and heat stabibity.The effect of Piromyces sp.CN6 on thefermentation quality,nutrient composition and in vitrodegradation of whole corn silagesThe aim of this study was to investigate the effect of anaerobic fungi inoculant on fermentation quality,nutrient composition,in vitrodegradation of whole corn silages.Asingle factor completely randomized was used in the experiment,each group had 5 replicates.The whole plant corn was used as silage material in three groups contained the control group,the fungi group(105 TFU/g)and the enzyme group(0.033 mg/g).Silages were sealed in polythene bags,stored at ambient temperature and analyzed after 10,30 and 60 days of ensiling.The results were showed as follows: the silage fermentation quality of the fungi group and the enzyme group as level 1and the silage fermentation quality of the control group as level 2.The rumen anaerobic fungi could reproduce and attach to the surface of maize stem and leaf in the early stage of silage.Compared with the control group,silages treated with the fungi inoculant and enzyme significantly decreased pH,acetic acid content,and NH3-N/TN in 30 days ensiling(P<0.05),decreased the NDF and ADF contents in 10,30,60 days ensiling significantly(P<0.05),and increased the water-soluble carbohydrates,the crude protein content,lactic acid contents,A:P ratio in 30 days ensiling significantly(P<0.05).The fungi treatment significantly increased IVDMD,IVNDFD and IVADFD at 48 h in 30 days ensiling(P<0.05).There was no significant difference on DMR of silages among different treatmants(P>0.05).Overall,this study indicated that the fungi inoculant improved the quality of corn silage,decreased the cell wall content and increased in vitro DM and crude fiber degradation.In the present study,12 anaerobic fungi strains were isolated from Xinong Saanen dairy goat,Piromyces sp.CN6 showed the highest plant cell wall degrading enzymes activity.Both xylanse and AE activity showed high activity in a wide range of temperature and pH,and had high pH and heat stability.What’s more the fungi inoculant can improve the quality of corn silage,and increase crude fiber degradation. |
