Endoglucanase activity of cellulolytic bacteria from lake sediments and its application in hydrophyte degradation

• Published in: FEMS microbiology letters 2020-12, Vol.367 (24), p.1
• Main Authors: Zhang, Hongpei, Li, Qianzheng, Zhao, Yuqing, Zhang, Mingzhen, Xu, Dong, Wu, Zhenbin, Zhou, Qiaohong
• Format: Article
• Language: English
• Subjects: Actinomycetales; Analysis; Aquatic ecosystems; Aquatic organisms; Aquatic plants; Bacillus (Bacteria); Bacteria; Bacteria - enzymology; Bacterial Proteins - metabolism; Biodegradation; Cellulase - metabolism; Cellulolytic bacteria; Cellulose; Correlation analysis; Endoglucanase; Enzymatic analysis; Geologic Sediments - microbiology; Hydrophytes; Identification and classification; Lake sediments; Lakes; Lakes - microbiology; Lignin; Methods; Microbiology; Organic matter; Physiological aspects; Plants - metabolism; Plants - microbiology; Pretreatment; Residues; Sediments; Soil Microbiology; Streptomyces; Submerged plants; Sugar
• ISSN: 1574-6968; 0378-1097; 1574-6968
• DOI: 10.1093/femsle/fnaa200

ABSTRACT Hydrophytes are plants that grow in or on water. Their overgrowth adversely affects the ecosystem because of crowding out other aquatic organisms and polluting the environment with plant residue. In principle, cellulolytic bacteria can be used to degrade hydrophyte biomass. We here isolated and characterized four cellulolytic bacterial strains from Lake Donghu sediments (Wuhan, China) that are rich in organic matter and plant residues. The isolates (WDHS-01 to 04) represent Bacillus, Micromonospora and Streptomyces genera. The bacteria exhibited pronounced endoglucanase activities (from 0.022 to 0.064 U mL–1). They did not extensively degrade the emerged plant Canna indica L. However, in an Hydrilla verticillata (submerged plant) degradation medium, strain WDHS-02 exhibited a high degradation rate (54.91%), endoglucanase activity of 0.35 U mL–1 and the conversion rate of cellulose to reducing sugars of 7.15%. Correlation analysis revealed that bacterial endoglucanase activity was significantly correlated with the degradation rate, and acid detergent lignin, ash and cellulose content of the residual H. verticillata powder. In conclusion, the identified bacteria efficiently decomposed submerged plants without the need for acid–base pretreatment. They expand the set of known cellulolytic bacteria and can be used for natural degradation of submerged plants. Cellulolytic strains with superior endoglucanase activities were isolated from the lake sediments, and the ADL, Ash and cellulose of residual Hydrilla verticillata powder could significantly affect endoglucanase activity of strains.