| In order to improve the decomposition efficiency of corn stover in the cold northeast region and break through the bottleneck of low temperature.This study explored the low-temperature lignocellulose-decomposing microbial consortium PLC-8 on the decomposition characteristics and microbial diversity of corn stover,and the effect of the microbial consortium on lignocellulose from different sources.Simplify the microbial consortium and study the effect of microbial consortium on the decomposition of corn stover and the dynamic changes of microorganisms.The results are as follows:(1)The results showed that microbial consortium PLC-8 decomposed corn stover:the pH droped and then rose to close to the original initial value;after 30 d,the weight-loss ratio of corn stover reached 43.65%;the content of hemicellulose,cellulose and lignin decreased respectively by 61.13%,40.91%and 14.25%.Cellulase activity increased and then decreased.The filter paper enzyme andβ-glucosidase activities were on 20 d,which were respectively 0.0540 U·mL-1 and 0.025 U-mL-1.The highest endonuclease and exonuclease activities were on the 15 d,which were respectively 0.0320 U·mL-1 and 0.0300 U·mL-1;Xylanase activity gradually increased with the decomposition of corn stover.The highest values of formic acid and acetic acid were respectively on the 20 d and 15 d.Microbial community analysis showed that PLC-8 is composed of bacterium and fungi,which has decomposition stability.The dominant strains of bacterium at the genus level are Chryseobacterium;Brevundimonas;Acinetobacter;the dominant strain of fungus at the genus level is Hypocreales.(2)The results showed that microbial consortium PLC-8 decomposed lignocellulose from different sources:the pH changed in the process of the microbial consortium decomposed filter paper,printing paper,paper boxes,newspapers,and cotton showed a regular pattern:"First drop to slightly acidic,then gradually rise back to slightly alkaline ";after 30 d,the weight loss rates of filter paper,printing paper,paper box,newspaper,cotton were 45.49%,73.72%,29.59%,30.16%,12.64%;the content of hemicellulose decreased respectively by 16.44%,77.31%,45.99%,44.40%,15.46%;the content of cellulose decreased respectively by 11.23%,72.40%,44.35%,49.67%,5.00%;the content of lignin decreased respectively by 5.27%,22.16%,9.22%,9.71%,4.26%;the cellulase activity of the microbial consortium during the decomposition of different substrates first increased and then decreased,the highest cellulase activity using printing paper as the substrate,its filter paper enzymes,endonucleases,exonuclease and β-glucosidase all reached the highest value on the 20 d,which were 0.0580 U·mL-1,0.0381 U·mL-1,0.0631 U·mL-1,0.0498 U·mL-1;The xylanase activity of the printing paper substrate was the highest relative to other substrates,and reached the highest value on the 15 d,which is 0.0700 U·mL-1;during the decomposition of different substrates,the formic acid and acetic acid accumulation of the printing paper are higher than others,and at the 30 d,formic acid reached 0.2070 g·L-1 and acetic acid reached 3.4837 g·L-1.This showed that microbial consortium decomposed printing paper best.(3)Using traditional microbiological methods,11 strains of bacterium and 2 strains of fungi were selected from the microbial consortium PLC-8.After identification,the bacterium were:Kouria,Serratia,Sphingomonas,Brevibacterium,Flavobacterium,Staphylococcus,Rhodococcus,Pedobacter,Pseudomonas,Commamonas;The fungi were:Hypocreales,Penicillium.Used congo red agar,it was found that 4 strains of bacterium and 1 strain of fungus produced cellulase.(4)The results showed that artificially combining three groups of microbial consortium F1,F2,and F3 decomposed corn stover:F1:pH showed a downward trend;F2:pH showed an upward trend;F3:pH first decreased and then gradually rose to slightly alkaline.After 30 d,the microbial consortium F1,F2,and F3 decomposed corn stover,and the corn stover lost weight by 8.19%,26.78%,and 39.80%,the content of hemicellulose decreased respectively by 12.74%,41.53%,and 52.64%;the content of cellulose decreased respectively by 7.31%,14.10%,and 25.8%;the content of lignin decreased respectively by 0.76%,1.16%,and 6.26%.F3 had the highest cellulase and xylanase activity among the three groups of microbial consortium.Among them,the activities of filter paper enzyme,endonuclease,exonuclease,β-glucosidase and xylanase reached the highest on the 15 d,which were 0.0893 U·mL-1,0.0813 U·mL-1,0.0854 U·mL-1,0.0682 U·mL-1,0.1144 U·mL-1.F1 had the highest formic acid and acetic acid content on the 15 d which were 0.5413 g·L-1 and 0.5881 g·L-1;F2 had the highest formic acid and acetic acid content on the 20 d of culture,which were 0.2031 g·L-1 and 0.5923 g· L-1,respectively.F3 had the highest formic acid content at the 20 d of fermentation supernatant,which was 0.5486 g·L-1;F3 had the highest acetic acid content at the 10 d of fermentation supernatant,which was 0.5213 g·L-1.Among them,during the process of decomposing corn stover,the bacterium of microbial consortium F1 and F3 changed significantly. |
