Isolation and identification of sulphur oxidizing bacteria from freshwater fish farm soil
Isolation and identification of sulphur oxidizing bacteria from freshwater fish farm soil
Date
2018
Authors
Kumar, N.R.
Archana, K.K.
Basha, K.A.
Muthulakshmi, T.
Joseph, T.C.
Prasad, M.M.
Journal Title
Journal ISSN
Volume Title
Publisher
Society of Fisheries Technologists (India), Cochin
Abstract
Sulphur oxidizing bacteria (SOB) are natural microflora
in aquaculture farms that play a significant role
in sulphur cycle. In this study isolation, characterization
and sulphate ion production ability was
carried out to assess the role of SOB in utilizing
thiosulphate. Ninety six distinct morphological
isolates of SOB were isolated from the freshwater
fish farm soil employing six different isolation
media. Subsequent dye reduction test revealed that
16 isolates on Thiobacillus aquaesulis medium, 12
isolates on T. denitrificans medium, 9 isolates on T.
thioparus medium and 10 isolates on Thiothrix
medium showed characteristic color change of the
dye (bromo phenol blue). Eight sulphur oxidizing
bacterial isolates (SOBA17, SOBA12, SOBA3,
SOBA20, SOBD10, SOBD16, SOBD12 and SOBD14)
were selected for further studies based on the pH
reduction test. To screen the potential sulphur
oxidising bacteria, medium was amended with
sodium thiosulphate and the sulphate ion production
ability of the isolates was measured spectrophotometrically.
Bacterial isolate of SOBA17 (1.62 mg
ml-1) showed maximum sulphate ion production,
followed by SOBA20 (1.50 mg ml-1). The 16S rRNA
sequencing revealed that the isolates belonged to
Thiobacillus aquaesulis. The partially purified sulphur
oxidase of SOBA17 in SDS-PAGE exhibited three
consecutive protein bands of molecular weight 10,
17 and 30 kDa. The present study revealed that SOB
has the capacity to utilize sulphur in its oxidized
state to non-toxic sulphate. Further studies are
needed to understand the diversity and role of these
bacteria in sulphur dynamics in aquaculture farms.
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Citation
Fishery Technology 55(4):270-275