Isolation
of marine fungi Aspergillus sp. and its in vitro antifouling
activity against marine bacteria
Santhanamari
Thiyagarajan1*, Manoharan Bavya2 and Alruwaili Jamal1
1Department of
Microbiology, Faculty of Applied Medical Sciences, Northern Border
University, Arar-91431, Kingdom of Saudi Arabia
2P.G. and Research
Department of Microbiology, Asan Memorial College of Arts and Science,
Chennai-600 100, India
*Corresponding
Author E-mail: drsthiyagarajan@live.com
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Publication
Data
Paper received:
16 October 2014
Revised received:
19 October 2015
Re-revised received:
30 November 2015
Accepted:
15 January 2016
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Abstract
Biofouling
is considered as a main issue of concern in aquatic environment causing
severe economic loss and pollution. The aim of the present study was to
isolate marine fungus antagonistic to biofouling bacteria and to define
antifouling compounds present in it. Using standard plate method five
predominant biofouling bacteria viz., Methylococcus sp., Flavobacterium
sp., Marinococcus sp., Serratia sp. and Pseudomonas sp.
were isolated from marine solid substances on Zobell's agar. Tolerance range
of these bacteria to NaCl was 2-10%. Isolation of fungi from mangrove and
estuarine sediments and their screening identified Aspergillus sp. EF4
as a potential isolate. This isolate caused inhibition of all the five test
bacterial cultures measuring zone diameters respectively of 11, 16, 12, 13
and 11mm.? Subsequent to submerged fermentation using shaking flask method
this fungus produced bioactive compounds within 5 days. The culture
parameters optimized were raffinose as carbon source, yeast extract as lone
nitrogen source, pH up to 9.0 and temperature up to 40?C. Antifouling
compounds of culture filtrate were separated and detected by a three-step
procedure involving thin layer chromatography, bioautography and preparative TLC.
The in vitro assay involving glass slide-wooden stick-biofilm method revealed
that these compounds could cause inhibition and destruction of bacteria to an
extent of 2.16 x 104 CFU ml-1 and 2.46 x 104
CFU ml-1 respectively while growth of bacteria in control beaker
was enumerated to be 4.41 x 104 CFU ml-1. High
performance liquid chromatography of culture filtrate indicated probable
principal antifouling compound as Fumonisin B2. Isolation of antagonistic
marine fungus from Indian coast and detection of its antifouling compound
would help in planning effective strategies for controlling biofouling in
marine environment.
Key
words
Antagonistic
fungi, Antifouling compound, Aspergillus sp., Bioautography,
Biofouling, Marine bacteria
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