Isolation And Degradation Characteristics Of Cellulose Degrading Bacteria From Rumen Of Black Goats

Cellulose,as the most abundant renewable resource on the earth,is burned and discarded except for a small part of the crop straw,which not only has not been used efficiently,but also has caused serious environmental pollution.At present,the treatment methods of cellulose include physical degradation,chemical degradation and biodegradation.The biodegradation of cellulose has become a hotspot because it conforms to the concept of green,ecological and environmental protection.There are a lot of cellulose-degrading bacteria in rumen of ruminants,so ruminants digest and degrade cellulose efficiently.Black goats,as ruminants,are mainly raised as poultry in southern provinces of China.It has strong digestive capacity and rapid growth,and is recognized as a local fine variety of pollution-free herbivores in China.At present,rumen microorganisms of ruminants are mainly studied by cattle,deer and camels at home and abroad,while the research on rumen microorganisms of black goats is still blank.The purpose of this study was to isolate and screen cellulose-degrading bacteria from the rumen of black goats,and to study their degradation characteristics,so as to provide theoretical basis and practical basis for the rapid decomposition of straw in the future,especially in the double cropping rice stubble.The results are as follows:(1)Isolation,Screening and Identification of Cellulose Degrading BacteriaSixteen strains of cellulose-degrading bacteria were obtained by enriching and diluting the rumen contents of black goats from Changsha Red Star slaughter market.Four strains of cellulose-degrading bacteria L1,C3,B4 and L6 were screened by Congo red staining and filter paper disintegration test.16 S r DNA sequencing and phylogenetic analysis showed that L1 was Ochrobactrum anthropi,C3 was Klebsiella variicola,B4 was Acinetobacter lactucae and L6 was Klebsiella pneumoniae.(2)Enzyme Activity of Cellulose Degrading BacteriaUsing rice straw as the sole carbon source,four strains were cultured to produce enzymes by fermentation.Their CMCase and FPA activities were determined by 3-5 dinitrosalicylic acid colorimetry(DNS).The results showed that the activity of CMCases of the four strains was L6 > L1 > C3 > B4,and the order was 96U/m L,74U/m L,67U/m L and 47U/m L.Among them,the highest activity of CMCase was L6 strain and the lowest was B4 strain.The activity of FPA enzyme was L6 > L1 > C3 > B4,71 U/m L,51 U/m L,45 U/m L and 38 U/m L,respectively.The highest activity of FPA was L6 strain and the lowest was B4 strain.Generally speaking,CMCase activity is more than 50 U/m L and FPA activity is more than 40 U/m L.It is considered that the strain is a cellulase-producing strain.Therefore,the strains L1,C3 and L6 obtained in this study are all cellulase-producing strains.(3)Degradation characteristics of cellulose-degrading bacteriaUsing filter paper and rice straw as substrates,the dry weights of filter paper and straw were measured on the 5th and 10 th days,and the degradation rates of filter paper and rice straw were calculated.The results showed that the degradation of filter paper by the tested strains was better than that of rice straw.On the 10 th day,the degradation rate of filter paper L6 > L1 > C3 > B4 was 92.5%,85.5%,70.2% and 60.9% respectively,and that of rice straw L6 > L1 > C3 > B4 was 37.7%,23.9%,20.2% and 11%,respectively.The results were consistent with the results of enzyme activity determination,which further verified the ability of four cellulose-degrading bacteria to produce enzymes and the ability of rice straw degradation.