Characterization of thermotolerant Acetobacter pasteurianus strains and their quinoprotein alcohol dehydrogenases

Abstract

We isolated several thermotolerant Acetobacter species of which MSU10 strain, identified as Acetobacter pasteurianus, could grow well on agar plates at 41 degrees C, tolerate to 1.5% acetic acid or 4% ethanol at 39 degrees C, similarly seen with A. pasteurianus SKU1108 previously isolated. The MSU10 strain showed higher acetic acid productivity in a medium containing 6% ethanol at 37 degrees C than SKU1108 while SKU1108 strain could accumulate more acetic acid in a medium supplemented with 4-5% ethanol at the same temperature. The fermentation ability at 37 degrees C of these thermotolerant strains was superior to that of mesophilic A. pasteurianus IFO3191 strain having weak growth and very delayed acetic acid production at 37 degrees C even at 4% ethanol. Alcohol dehydrogenases (ADHs) were purified from MSU10, SKU1108, and IFO3191 strains, and their properties were compared related to the thermotolerance. ADH of the thermotolerant strains had a little higher optimal temperature and heat stability than that of mesophilic IFO3191. More critically, ADHs from MSU10 and SKU1108 strains exhibited a higher resistance to ethanol and acetic acid than IFO3191 enzyme at elevated temperature. Furthermore, in this study, the ADH genes were cloned, and the amino acid sequences of ADH subunit I, subunit II, and subunit III were compared. The difference in the amino acid residues could be seen, seemingly related to the thermotolerance, between MSU10 or SKU1108 ADH and IFO 3191 ADH.

Identification and characterization of thermotolerant acetic acid bacteria strains isolated from coconut water vinegar in Sri Lanka

“…The results obtained were similar to those published for other thermotolerant AAB. 21,23) On the other hand, mesophilic A. pasteurianus IFO3191 did not grow on potato agar plates at 39°C even in the absence of ethanol and of acetic acid, while A. pasteurianus IFO3284 grew on a potato agar plate at 39°C but not at 41°C. It tolerated 1% acetic acid at 39°C and only 4% ethanol at 37°C.…”

“…It tolerated 1% acetic acid at 39°C and only 4% ethanol at 37°C. 23) Since SL13E-2, SL13E-3, and SL13E-4 grew well at up to 42°C and tolerated acetic acid and ethanol at elevated temperatures, they are considered thermotolerant AAB. Similarly, SL13-5, SL13-6, SL13-7, and SL13-8 are also considered thermotolerant Gluconobacter AABs, because although the mesophilic type strain, G. frateurii IFO3276, does not grow at 37°C, these strains do grow, like the thermotolerant isolates from Thailand.…”

The Key to Acetate: Metabolic Fluxes of Acetic Acid Bacteria under Cocoa Pulp Fermentation-Simulating Conditions

“…1) was derived from the genomic repertoire of A. pasteurianus IFO 3283 and A. pasteurianus 386B, which have recently been sequenced (21,40). A. pasteurianus possesses membrane-bound, pyrroloquinoline quinone (PQQ)-dependent alcohol and aldehyde dehydrogenases for oxidation of ethanol into acetate, as well as genes encoding intracellular alcohol dehydrogenase and aldehyde dehydrogenase (see Table S1 in the supplemental material) (21,(40)(41)(42)(43). Lactate is metabolized via lactate dehydrogenase and further metabolized into acetate (26).…”

Membrane-Bound Alcohol Dehydrogenase Is Essential for Glyceric Acid Production in Acetobacter tropicalis

“…4a . PQQ-containing quinoproteins have a common basic structure called a propeller fold superbarrel made up of eight four-stranded anti-parallel β-sheets called W motifs because they look like the letter W 18,19 . In the AdhA sequence, W-motifs W1-W8 were also conserved see Fig.…”