Biodegradation of high-concentration isopropanol by a solvent-tolerant thermophile, Bacillus pallidus
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Date
2002
Journal Title
Journal ISSN
Volume Title
Publisher
Springer Verlag
Abstract
The aerobic biodegradation of high-concentration,
to 24 g l
–1
, 2-propanol (IPA) by a thermophilic isolate
ST3, identified as
Bacillus pallidus
, was successfully carried
out for the first time. This solvent-tolerant
B. pallidus
utilized
IPA as the sole carbon source within a minimal salts
medium. Cultivation was carried out in 100-ml shake flasks
at 60°C and compared with cultivation within a 1-l stirred
tank reactor (STR). Specific growth rate () was about
0.2 h–1
for both systems, with a maximum cell density of 2.4 x 10
8 cells ml–1
obtained with STR cultivation. During exponential
growth and stationary phase, IPA biodegradation
rates were found to be 0.14 and 0.02 g l
–1h–1, respectively, in
shake-flask experiments, whereas corresponding values of
0.09 and 0.018 g l
–1h–1
were achievable in the STR. Generation
of acetone, the major intermediate in aerobic IPA biodegradation,
was also monitored as an indicator of
microbial IPA utilization. Acetone levels reached a maximum
of 2.2–2.3 g l–1
after 72 and 58 h for 100-ml and 1-l systems,
respectively. Both IPA and acetone were completely
removed from the medium following 160 and 175 h, respectively,
during STR growth, although this was not demonstrated
within shake-flask reactions. Growth of
B. pallidus
on acetone or IPA alone demonstrated that the maximum
growth rate () obtainable was 0.247 h–1
at 4 g l–1
acetone
and 0.202 h–1
at 8 g l–1
IPA within shake-flask cultivation.
These results indicate the potential of the solvent-tolerant
thermophile
B. pallidus
ST3 in the bioremediation of hot
solvent-containing industrial waste streams.
Description
Keywords
Biodegradation, Bacillus pallidus, Isopropanol (IPA), Solvent tolerant, Volatile organic compounds (VOCs), Thermophilic
Citation
Bustard, M.T., Whiting, S., Cowan, D.A., Wright, P.C. (2002). Biodegradation of high concentration solvents by a solvent tolerant thermophile, Bacillus pallidus. Extremophiles, 6:319-323.