Isolation and characterization of cellulose-degrading bacteria from the deep subsurface of the Homestake gold mine, Lead, South Dakota, USA

• Published in: Journal of industrial microbiology & biotechnology Vol. 36; no. 4; pp. 585 - 598
• Main Authors: Rastogi, Gurdeep, Muppidi, Geetha L, Gurram, Raghu N, Adhikari, Akash, Bischoff, Kenneth M, Hughes, Stephen R, Apel, William A, Bang, Sookie S, Dixon, David J, Sani, Rajesh K
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Berlin/Heidelberg : Springer-Verlag 01.04.2009; Springer-Verlag; Springer; Springer Nature B.V
• Subjects: Agriculture; Alternative energy sources; Bacillus; Bacteria; Bacteria - classification; Bacteria - genetics; Bacteria - isolation & purification; Bacteria - metabolism; Bacterial Proteins - chemistry; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Biochemistry; biodegradation; Biodiesel fuels; Biofuels; Bioinformatics; Biological and medical sciences; Biomass; Biomedical and Life Sciences; Biotechnology; Brevibacillus; Carbon; Cellulase - chemistry; Cellulase - genetics; Cellulase - metabolism; cellulolytic microorganisms; Cellulose; Cellulose - metabolism; Contamination; DNA, Ribosomal - genetics; enzyme activity; Enzyme Stability; Enzymes; Firmicutes; Fundamental and applied biological sciences. Psychology; Genetic Engineering; Geobacillus; Geologic Sediments - chemistry; Geologic Sediments - microbiology; Gold; Gold mines & mining; High temperature; Inorganic Chemistry; Laboratories; Lead; Life Sciences; Lignocellulose; Microbiology; Microorganisms; mined soils; Mines; Mining; Molecular Sequence Data; molecular systematics; Original Paper; Paenibacillus; Phylogeny; RNA, Bacterial - genetics; RNA, Ribosomal, 16S - genetics; soil bacteria; soil chemical properties; soil weathering; South Dakota; Spectrum analysis; Studies; thermal stability; South Dakota; Cellulose-degrading bacteria; Thermostable enzymes; Deep subsurface; Gold mine; DUSEL; Gold; Enzyme; Cellulose; Thermal stability; Characterization; Degradation; Mine; Bacteria; Isolation; Subsurface
• ISSN: 1367-5435; 1476-5535
• DOI: 10.1007/s10295-009-0528-9

The present study investigated the cultivable mesophilic (37°C) and thermophilic (60°C) cellulose-degrading bacterial diversity in a weathered soil-like sample collected from the deep subsurface (1.5 km depth) of the Homestake gold mine in Lead, South Dakota, USA. Chemical characterization of the sample by X-ray fluorescence spectroscopy revealed a high amount of toxic heavy metals such as Cu, Cr, Pb, Ni, and Zn. Molecular community structures were determined by phylogenetic analysis of 16S rRNA gene sequences retrieved from enrichment cultures growing in presence of microcrystalline cellulose as the sole source of carbon. All phylotypes retrieved from enrichment cultures were affiliated to Firmicutes. Cellulose-degrading mesophilic and thermophilic pure cultures belonging to the genera Brevibacillus, Paenibacillus, Bacillus, and Geobacillus were isolated from enrichment cultures, and selected cultures were studied for enzyme activities. For a mesophilic isolate (DUSELG12), the optimum pH and temperature for carboxymethyl cellulase (CMCase) were 5.5 and 55°C, while for a thermophilic isolate (DUSELR7) they were 5.0 and 75°C, respectively. Furthermore, DUSELG12 retained about 40% CMCase activity after incubation at 60°C for 8 h. Most remarkably, thermophilic isolate, DUSELR7 retained 26% CMCase activity at 60°C up to a period of 300 h. Overall, the present work revealed the presence of different cellulose-degrading bacterial lineages in the unique deep subsurface environment of the mine. The results also have strong implications for biological conversion of cellulosic agricultural and forestry wastes to commodity chemicals including sugars.