Screening Of Cellulose-degrading Actinomycetes From Cold Region And Black Glebe And Taxonomic Identification Of HUCO-GS316

Corn straw is a kind of cheap and renewable cellulose biological resource.Due to the complexity and high inertia of the natural cellulose structure in corn straw,it is difficult to degrade naturally,resulting in waste of resources and environmental pollution.As a method of degrading cellulose,microorganism has attracted more and more attention because of its mild reaction conditions,small investment,low cost and no pollution.Compared with other microorganisms,actinomycetes have many advantages,such as:they can produce and secrete a variety of hydrolases,simple structure,easy genetic analysis and improve the soil environment,with the characteristics of heat resistance,metabolic diversity and adaptability to extreme environment.At present,the research results show that actinomycetes have relatively high cellulase activity,and the production capacity of cellulase can be improved by building a multiple microorganisms,so as to achieve the purpose of effective utilization of straw cellulose.The cold region and black glebe is a kind of high cold black soil with deep humus layer,which is a unique resource for strain selection.In this study,a group of multiple microorganisms with cellulose degradation ability was screened and constructed from the cold region and black glebe of Mudanjiang City,and the degradation efficiency of corn straw was analyzed.Finally,the new actinomycete HUCO-GS316 was classified and identified.The main research contents and results are as follows:（1）Screening of actinomycetes for efficient degradation of cellulose:gause’s synchrotagarno.1（GS）,cellulose proline medium（CPA）,amino acid medium（AAG）and dulcitol proline medium（DPA）were used to screen actinomycetes from the cold region and black glebe of Mudanjiang.The potential strains of cellulase activity were screened and rescreened.The results showed that 129 different actinomycetes were screened from the cold region and black glebe.In the preliminary screening experiment,8 strains produced clear circles,and 3 strains with better cellulase production capacity were obtained through the re-screening experiment.（2）Identification of cellulolytic strain:through morphological characteristics and molecular biological level,the isolated strains with cellulose degrading ability were preliminarily identified.The results showed that the morphological observation of GS-3-39,GS-4-21 and CPA-3-4 accorded with the morphological characteristics of actinomycetes.The16S r RNA sequence of strain GS-3-39 is 1,507 bp,confirming that it belongs to Micromonospora;the 16S r RNA sequence of strain GS-4-21 is 1,518 bp,confirming that it belongs to Streptomyces;the 16S r RNA sequence of strain CPA-3-4 is 1,518 bp,confirming that it belongs to Streptomyces.（3）Construction of composite flora and degradation of corn stalks:construction of composite flora,response surface method to optimize the conditions of composite bacteria degradation of corn stalks,and finally scanning electron microscope to observe the structure changes of corn stalks before and after degradation Changes in content.The study found that there is no antagonism between the strains GS-3-39,GS-4-21 and CPA-3-4,and the construction of complex flora can be carried out.Among them,combination 1 had the highest enzyme activity,and its FPA enzyme activity,C₁ enzyme activity,C_X enzyme activity andβ-glucosidase enzyme activity reached 24.12±1.26 U/m L,25.31±0.42 U/m L,55.80±0.74 U/m L,and 49.13±0.29 U/m L.When the initial p H of the culture medium was 7,the inoculation amount was 3%,and the fermentation rate of the corn stalk was good with the composite bacteria group,the degradation rate reached 38.24%.Among them,cellulose,hemicellulose and lignin degraded 33.97%,34.08%and 21.52%,respectively.Scanning electron microscopy results showed that the composite flora had a good ability to degrade corn stalks.（4）Taxonomic identification of a new actinomycete HUCO-GS316:Strain HUCO-GS316with 16S r RNA sequence similarity<99%was classified and whole genome sequenced.The results showed that the 16S r RNA sequence similarity of the strain HUCO-GS316 was 98.55%（Streptomyces cyslabdanicus）and the strains with high similarity were all Streptomyces genus,which formed a separate phylogenetic tree with Streptomyces Kebangsaanensis SUK12^T（98.44%）Branch to determine that it belongs to the genus Streptomyces.Because the strains HUCO-GS316 and Streptomyces Kebangsaanensis SUK12^T have large differences in morphology and culture characteristics,physiological and biochemical,it can be preliminarily judged that the strain HUCO-GS316 is a new species of Streptomyces.Whole genome sequencing results show that the strain HUCO-GS316 has multiple genetic components and multiple predicted biological functions.The strain HUCO-GS316 was deposited in China General Microbial Culture Collection Management Center（CGMCC 4.7630）and Thailand Institute of Science and Technology（TISTR 2812）.