Global Analysis of the Genes Involved in the Thermotolerance Mechanism of ThermotolerantAcetobacter tropicalisSKU1100

Abstract

Acetobacter tropicalis SKU1100 is a thermotolerant acetic acid bacterium that grows even at 42 °C, a much higher temperature than the limit for the growth of mesophilic strains. To elucidate the mechanism underlying the thermotolerance of this strain, we attempted to identify the genes essential for growth at high temperature by transposon (Tn10) mutagenesis followed by gene or genome analysis. Among the 4,000 Tn10-inserted mutants obtained, 32 exhibited a growth phenotype comparable to that of the parent strain at 30 °C but not at higher temperatures. We identified the insertion site of Tn10 on the chromosomes of all the mutant strains by TAIL (Thermal Asymmetric Interlaced)-PCR, and found 24 genes responsible for thermotolerance. The results also revealed a partial overlap between the genes required for thermotolerance and those required for acetic acid resistance. In addition, the origin and role of these thermotolerant genes are discussed.

Complete Genome Sequencing and Comparative Genomic Analysis of the Thermotolerant Acetic Acid Bacterium, <i>Acetobacter pasteurianus</i> SKU1108, Provide a New Insight into Thermotolerance

“…In order to identify the genes whose expression is required for growth at higher temperatures, we previously mutated the A. tropicalis SKU1100, a thermotolerant AAB that grows even at 42°C, by transposon mutagenesis, thereby inducing random insertions in the Tn 10 transposon using a conjugation method (30). We revealed that 24 “thermotolerant” genes (see Table 2 or Table S4) were associated with growth at higher temperatures.…”

“…The 24 thermotolerant genes conserved in A. tropicalis NBRC 101654 (=SKU1100) and their homologous sequences were also searched for in the three A. pasteurianus complete genomes by BLASTP with an E-value cut-off of 10 −10 and sequence overlap (query and subject) ≥70% (1, 30). …”

Bioconversion of Biodiesel-derived Crude Glycerol to 1,3 Dihydroxyacetone by a Potential Acetic Acid Bacteria

“…BACTERIA AND GROWTH CONDITIONS YPGD medium consisting of 0.5% (w/v) glucose, glycerol, yeast extract and peptone (Soemphol et al 2011) was used to prepare the seed culture. The cultivation was carried out on a rotary incubator shaker (Vision Scientific Co., Ltd. Korea) at 200 rpm at 30°C for 24 h. All newly isolated acetic acid bacteria (AAB) were previously isolated from natural resources.…”

“…Five percent (v/v) of each cell culture was then transferred into 5 mL of YPGc, which was modified as described by Soemphol et al (2011) and consisted of 10% crude glycerol (by weight), 0.5% yeast extract, 0.5% peptone and 0.1% MgSO 4 . Finally, the pH of the medium was adjusted to 6.5 using conc.…”

“…)/H + antiporter of A. tropicalis SKU1100, was constructed (Soemphol et al 2011) and transformed into competent cells of G. frateurii NKC115 by electroporation, according to a previous report (Soemphol et al 2008). The transformant was selected for on YPGD agar medium containing 12.5 mg/mL of tetracycline.…”