Screening Of Bacterial Strains With Straw-Ligninolytic Activitises

As a renewable resource,straw has great potential value, which cannot be effectively used under natural conditions due to its complex structure.How to use the straw resources effectively has become an urgent problem to be solved in our country.In recent years, the biodegradation of lignin has attracted much attention. At present, the most studied ligninolytic strain is white-rot fungus, produced by which thethree kinds of ligninolytic enzymeshavebeenstudiedalot. However,white-rot fungus has long fermentation time, and its growth is easily subject to environmentalimpact,so the efficiency is not high in actual production practice.In summary, it is of great significance to screen efficient bacterial strain of lignin degradation for effective utilization of straw resources.In this study,bacterial strainswith alkali ligninolytic antivitiseswerescreened from Qinling Mountains and Xinjiang wood samples.The strains with straw lignin degradation potential were screened out by aniline blue decolorization test and lignin enzyme activity detection.Finally, the transformation of the straw which pretreatmentedbystrains screened out had been investigated. Through the study, the following conclusionscan be drawn:1. 58 strains were screened from 5 wood samples of Qinling Mountains and Xinjiang. Through the 16 S rDNA sequence homology analysis,the identification results showed that58 strains of bacteriacontain20 species,including Pseudomonas 、 Acinetobacter 、Burkholderia 、 Ochrobactrum 、 Leclercia 、 Lelliottia 、 Enterobacter 、 Raoultella andEnterobacter,a total of 9 generas.Among them, the number of strains of Pseudomonas was the most, there were 27 strains.2. Through the aniline blue decolorization test, 11 strains, Y5,Y7,H1, J2, J6, J9, J10, J11, J12, Q4 and Q16 showed obvious decolorization of aniline blue.Lignin enzyme activity test results showed that the enzyme activities of H1, J12 and Q4 were higher than those of other strains. Themaximum enzyme activity of laccase of strain J12 was 6.167 U/L, the maximum enzyme activity of lignin peroxidase of strain J12 was 4.032 U/L, the maximum manganese peroxidase enzyme activity of strain J12 was 1.119 U/L; the maximum enzyme activity of the three enzymes of strain Q4 were 5.750 U/L, 2.742 U/L and 1.406 U/L, respectively; the maximum enzyme activity of the three enzymes of H1 strains were 700 U/L, 4.919 U/L and 0.181U/L, respectively.3.Thegrowth ofstrain H1, J12 and Q4 had been studied. The results showed that, strains H1 entered the logarithmicgrowth phase within 20 h and entered stationary phasewithin30 h; strain J12 entered the logarithmic phasewithin6 h and enteredstationary phasewithin14 h; strain Q4 entered the logarithmic growth phase within 4 h, after 8 h of logarithmic phaseenteredthe stable period.4. Wheat strawand and corn stover were pretreated with each of strain H1, J12 and Q4, and then the components of straw degradation were analyzed.The results showed that lignin degradation rate on wheat straw of strain J12, Q4 and H1 were 1.89%, 1.39% and 0.69%, respectively; the lignin degradation rate oncorn stover were 1.93%, 1.76% and 1.08%, respectively.The three strains of bacteria have a certaineffect on the degradation of straw lignin, but furtherresearch is needed.