Characterizing corn-straw-degrading actinomycetes and evaluating application efficiency in straw-returning experiments

Abstract

Corn straw is an abundant lignocellulose resource and by-product of agricultural production. With the continuous increase in agricultural development, the output of corn straw is also increasing significantly. However, the inappropriate disposal of straw results in wasting of resources, and also causes a serious ecological crisis. Screening microorganisms with the capacity to degrade straw and understanding their mechanism of action is an efficient approach to solve such problems. For this purpose, our research group isolated three actinomycete strains with efficient lignocellulose degradation ability from soil in the cold region of China: Streptomyces sp. G1T, Streptomyces sp. G2T and Streptomyces sp. G3T. Their microbial properties and taxonomic status were assessed to improve our understanding of these strains. The three strains showed typical characteristics of the genus Streptomyces, and likely represent three different species. Genome functional annotation indicated that most of their genes were related to functions like carbohydrate transport and metabolism. In addition, a similar phenomenon also appeared in the COG and CAZyme analyses, with a large number of genes encoding carbohydrate-related hydrolases, such as cellulase, glycosidase and endoglucanase, which could effectively destroy the structure of lignocellulose in corn straw. This unambiguously demonstrated the potential of the three microorganisms to hydrolyze macromolecular polysaccharides at the molecular level. In addition, in the straw-returning test, the decomposing consortium composed of the three Streptomyces isolates (G123) effectively destroyed the recalcitrant bonds between the various components of straw, and significantly reduced the content of active components in corn straw. Furthermore, microbial diversity analysis indicated that the relative abundance of Proteobacteria, reportedly associated with soil antibiotic resistance and antibiotic degradation, was significantly improved with straw returning at both tested time points. The microbial diversity of each treatment was also dramatically changed by supplementing with G123. Taken together, G123 has important biological potential and should be further studied, which will provide new insights and strategies for appropriate treatment of corn straw.

The Role of Soil Microbial Consortia in Sustainable Cereal Crop Residue Management

“…Another research conducted by Gong and his colleagues on the characterization of maize-straw-degrading actinomycetes revealed that a consortium composed of the three Streptomyces spp. showed a decomposition rate of 51.60% after 77 days, significantly reducing the content of recalcitrant components in the maize straw [ 170 ]. A metatranscriptomic analysis of compost-derived microbial communities enriched on rice straw under thermophilic and mesophilic conditions showed significant overexpression of enzymes from glycoside hydrolase family 48 and carbohydrate-binding modules families 2 and 33 in the thermophilic community, predominantly expressed by the actinobacteria genus Micromonospora [ 171 ].…”

Straw from Different Crop Species Recruits Different Communities of Lignocellulose-Degrading Microorganisms in Black Soil

“…This method is environmentally friendly, requires minimal energy input, is cost-effective, and operates under mild conditions [5]. Microorganisms imparting biodegradation encompass bacteria, fungi, and actinomycetes [6]. Nevertheless, studies focusing on lignocellulose-degrading microorganisms indicate that fungi are sensitive to surrounding environmental conditions and are unsuitable for largescale industrial production [7,8].…”

Enhanced Biosynthesis of Phenazine-1,6-dicarboxylic Acid in Streptomyces coelicolor

“…Besides, most related studies are focused on Pseudomonas strains while phenazine-producing Streptomyces strains are omitted. Streptomyces strains can not only produce various bioactive secondary metabolites but also utilize a wide array of materials as carbon sources including cellulose, xylan, and other lignocellulosic compositions. − For example, two xylanases with high alkaline and thermostability were characterized from Streptomyces sp. B6 .…”