Complex microbial communities from river
biofilms might contain microorganisms capable of
degrading xenobiotic pollutants such as pesticides (e.g.
methomyl, which is commonly detected in rivers). Therefore,
this study was used to determine the methomyl degradation
potential of bacteria consortia and single bacterial
strains acclimatized and isolated from natural river biofilms
to provide biomaterials for bioremediation of water that is
contaminated with methomyl. Natural river biofilms were
culture enriched with methomyl as the sole carbon source
to obtain acclimatized bacterial consortia and single bacterial
strains. The microbial consortium on the ceramic
discs was able to remove 91 % of added methomyl
(50 mg l
-1) in 7 days. The longer-acclimatized bacterial
consortium on loofah sponges removed methomyl more
quickly than the shorter-acclimatized consortium, but both
had similar removal capabilities (i.e. 92.4 and 92.2 %).
This finding suggested that the former might contain more
methomyl degraders than the latter. However, after preservation
at 25, 4 and -20 ºC for 1 or 3 months, the
methomyl degradation ability of the bacterial consortia
decreased significantly, indicating loss of methomyl
degraders during preservation. Three bacterial species were
isolated from acclimatized river biofilms, and only one
species, identified as
Sphingomonas
sp., was able to
remove methomyl, with a 7-day removal rate of 44.7 %
when sugar was added and of 32.5 % when no sugar was
added. These results suggested that an additional carbon
source might slightly improve the ability of
Sphingomonas
sp. to degrade methomyl. Acclimatized bacterial consortia
have a higher potential for treating methomyl-contaminated
water than isolated bacterial species.
