Construction And Functional Evaluation Of Novel Lignocellulose Degradation Microbial Consortia At Low Temperature

In order to biodegrade lignocellulose at low temperature,this research came up with the addition of functional microbial consortia.To construct microbial consortium which is able to degrade lignocellulose and easy – to enlarge,we collected microorganisms from forest topsoil.After that,the microorganisms were enriched at the low temperature using minimal mediums and waste paper was regarded as the sole carbon source.Enriched microorganisms were screened,isolated and identified us R2 A medium.The identified microorganisms were using in straw and paper biodegradation.Besides,the influence of these microorganisms in straw returning was studied as well.Results are as follows:The lignocellulose degradation consortium was enriched after the cultivation process.57 strains were got after screen,isolation and identification using R2 A medium.All the strains belonged to six genera,including 23 Sphingobacterium strains,8 Flavobacterium strains,11 Pedobacter strains,10 Arthrobacter strains,3 Delftia strains and 2 Spingomonas strains.All microorganisms were capable to degrade lignocellulose,which produce and secrete enzymes to decompose all components of lignocellulose.Both the constructed easy – to enlarge consortium and the enriched consortium had the ability to degrade straw and waste paper.After 15 days degradation process,the degradation degree of straw reached 53.4 % and 52.0 %(constructed consortia and original consortia respective),while the degradation degree of paper was 24.2 % and 21.8 %(constructed consortia and original consortia respective).Among all the components of lignocellulose,the degradation effect of hemicellulose was the best,the degradation effect of lignin was the second and the degradation ability of cellulose was the weakest.SEM,TGA analyze results showed the destruction of straw and paper surface,the decrease of the aromatic ring and the decrease of cellulose chain length.The enzyme activity and degradation rate analyze results showed the constructed consortia were able to secreted more enzymes and degrade lignin more efficiently when the inoculation the equal microorganisms.PLFAs analyze result showed the compositions different consortia with different incubation consortia type,viz constructed consortia and original consortia,and the carbon source type,viz waste paper and straw,were similar(correlation > 0.8,P < 0.05).Among all the microorganism,the Gram Positive strains had the highest proportion as high as 35.1 %.A one-month simulation experiment showed the exogenous microorganism that we added had significant effect on the mend of soil quality and the improvement of soil nutrient content.The moisture contents were improved obviously of straw returning groups compared to the control groups.The straw returning would decrease the soil pH so that the soil would get acidic with straw returning.The addition of exogenous microorganisms would make the soil closer to neutral.The microbial biomass carbon content increased obviously with the addition of exogenous microorganisms.Besides,other kinds of soil nutrients,such as total organic carbon,total nitrogen and available nitrogen increased as well.The enzymes related lignocellulose degradation,viz laccase and cellulase enzyme activity showed a visible increase trend.The physical and chemical properties and the soil nutrients were different with the same carbon source type and different consortia type(original consortia,constructed consortia).The results showed the addition of exogenous microorganisms,especially constructed consortia were beneficial to improve the effectiveness of straw returning,the function in maintaining soil structure and improvement the soil nutrients content.