Characterization of Acinetobacter SP. LWC1 isolated from contaminated water and its survivability under different stress condition
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Date
2014-09
Authors
Lim, Wui Chen
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Abstract
The role of PHA in the survival of bacteria in contaminated waters was
investigated in this study. This study began with the isolation of a bacterium from water
contaminated with domestic wastes, followed with the identification and characterization
of the isolate and ended with the stress treatments to it. Based on the 16S rDNA, this
isolate was closer to the Acinetobacter spp. Therefore, it was designated as Acinetobacter
sp. LWC1. Besides this, the effect of various types of carbon sources such as sugars, oils
and carboxylic acids and medium on PHA production was investigated in this study.
Among all of the sugars, LB with 2% (w/v) of glucose yield the highest PHA content (11%
DCW) with 0.4 g/L dry cell weight at 48 h. Meanwhile for the oils, LB with 3% (v/v) of
used engine oil gave the highest PHA content (6.6% DCW) with 1.4 g/L dry cell weight at
72 h. The biosynthesis of P(3HB-co-3HV) copolymer was also evaluated in this study.
However, it was recorded as second highest PHA content (9.14% DCW) with 0.98 g/L
dry cell weight and 70 mol% 3HV at 96 h in LB medium by using 2% (w/v) of glucose
supplemented with 0.25% (v/v) of valeric acid. For the MS medium, 2% (v/v) of used
engine oil with 0.5% (v/v) of propionic acid gave the highest PHA content (3.99% DCW)
with 0.30 g/L dry cell weight at 72 h. The relationships between PHAs accumulation in
enhancing the survivability of Acinetobacter sp. LWC1 were carried out by comparing the
bacteria with highest PHA and lowest PHA content under the same environmental stress
conditions. It was found that Acinetobacter sp. LWC1 containing high PHA content of 11%
DCW obtained from cultivation cultures in LB with 2% (w/v) glucose (LG) improved its
endurance against environmental stresses such as high temperature, UV irradiation,
ethanol treatment and osmotic pressure compared to the ones with low PHA content of 0.5%
DCW obtained from cultivation cultures in LB with 2% (w/v) lactose (LA) and LB with 2%
(v/v) palm oil (LPO) respectively.
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Keywords
Acinetobacter SP. LWC1