Presence and potential role of thermophilic bacteria in temperate terrestrial environments

Abstract

Organic sulfur and nitrogen are major reservoirs of these elements in terrestrial systems, although their cycling remains to be fully understood. Both sulfur and nitrogen mineralization are directly related to microbial metabolism. Mesophiles and thermophiles were isolated from temperate environments. Thermophilic isolates were classified within the Firmicutes, belonging to the Geobacillus, Brevibacillus, and Ureibacillus genera, and showed optimum growth temperatures between 50°C and 60°C. Sulfate and ammonium produced were higher during growth of thermophiles both for isolated strains and natural bacterial assemblages. They were positively related to organic nutrient load. Temperature also affected the release of sulfate and ammonium by thermophiles. Quantitative, real-time reverse-transcription polymerase chain reaction on environmental samples indicated that the examined thermophilic Firmicutes represented up to 3.4% of the total bacterial community RNA. Temperature measurements during summer days showed values above 40°C for more than 10 h a day in soils from southern Spain. These results support a potential role of thermophilic bacteria in temperate terrestrial environments by mineralizing organic sulfur and nitrogen ruled by the existence and length of warm periods.

Divergent extremes but convergent recovery of bacterial and archaeal soil communities to an ongoing subterranean coal mine fire

“…The proportion of dormant cells in soils is estimated to be as high as 80% (Lennon and Jones, 2011), and the importance of dormancy for microbial community assembly processes has been discussed at length (Nemergut et al , 2013). Specific to the Centralia coal mine fire disturbance, thermophiles are prime examples of microbial seed bank members that often have been found in environments that are improbable to permit their growth (for example, McBee and McBee, 1956; Hubert et al , 2009; Portillo et al , 2012). …”

Latitude-dependent underestimation of microbial extracellular enzyme activity in soils

“…An exponential increase of microbial respiration versus temperature has been reported although high temperature values were previously considered above any real or predicted climate (Townsend et al 1992). The presence in soils of active thermophilic bacteria (Marchant et al 2002(Marchant et al , 2008Portillo et al 2012) adds on to the finding of significant soil microbial activities during high temperature conditions. The hydrolysis of polymers and microbial activity at elevated temperatures show potential ecological and global relevance.…”

Microbial communities associated with wet flue gas desulfurization systems

“…The detection of mesophilic phylotypes in scales suggests some influence of the “fresh” process water microbial communities on scale-associated community composition, and it is possible that thermophiles were present in “fresh” waters, but were not detected in due to the application of insufficient sampling effort to “fresh” waters. Thermophilic bacteria have been isolated from temperate soils, and may maintain some level of metabolic activity at relatively low temperatures (i.e., ≤25°C; Marchant et al, 2002, 2008; Hubert et al, 2010; Portillo et al, 2012). These findings suggest that some thermophilic microorganisms may be cosmopolitan components of non-thermal ecosystems (albeit in low abundance), as members of the “rare biosphere” (Sogin et al, 2006; Elshahed et al, 2008; Galand et al, 2009).…”