The genus Thermotoga: recent developments

Abstract

The genus Thermotoga comprises extremely thermophilic (Topt > or = 70 degrees C) and hyperthermophilic (Topt > or = 80 degrees C) bacteria, which have been extensively studied for insights into the basis for life at elevated temperatures and for biotechnological opportunities (e.g. biohydrogen production, biocatalysis). Over the past decade, genome sequences have become available for a number of Thermotoga species, leading to functional genomics efforts to understand growth physiology as well as genomics-based identification and characterization of novel high-temperature biocatalysts. Discussed here are recent developments along these lines for this group of microorganisms.

Figure 1

Unrooted 16S rRNA tree of Thermotoga species created using the Mobyle portal (http://mobyle.pasteur.fr/).

Figure 2

Central metabolism of T. maritima indicating open reading frames encoding enzymes involved in catabolic pathways.

Figure 3

Transcriptional analysis biofilm formation in T. maritima [53]; (A) biofilm cell samples were collected from a high-temperature continuous anaerobic bioreactor where the encricled region shows biofilm formed on nylon mesh and reactor walls, (B) volcano plot showing differential gene expression in planktonic and biofilm T. maritima cells grown in chemostat culture at 80 °C (horizontal lines indicates Bonferroni correction).

Figure 4

Overview of the proposed peptide-based (TM0504) signaling mechanism in T. maritima [58, 88]. (A) Epifluorescence images of T. maritima mono-culture (left) and T. maritima and M. jannaschii co-culture (right), where T. maritima displays rod morphology while M. jannaschii is the cocci bound up in the middle of the aggregate; (B) TM0504 putative signalling peptide with its predicted cleavage site after the GG motif; (C) schematic of the T. maritima cells in the co-culture summarizing the predicted export pathway for TM0504; (D) Acridine orange (top) and Calcofluor (bottom) stained cells of T. maritima 30 min after dosing with either buffer PBS (right), or synthetic TM0504 peptide (left).