Objective
:
This study was aimed to isolate and screen marine s
ponge-associated bacteria producing anti-
Vibrio
compounds and to identify their
compounds from the bacterial extract.
Methods
:
Sponge-associated bacteria were isolated by spread
plate method. Their anti-
Vibrio
activity against
Vibrio parahaemolyticus, V. harveyi
,
and
V. vulnificus
was determined by dual culture test. Three potenti
al isolates were identified based on 16S-rRNA gene
analysis. All isolates
producing anti-
Vibrio
compounds was tested for their haemolytic characte
rs in blood agar medium. Anti-
Vibrio
activity of the most potential isolate
was also tested by using its supernatant, extract,
and concentrated culture. Chemical composition of c
rude extract derived from that isolate was
identified by GC-MS analysis.
Results
:
68 bacterial isolates have been isolated from the m
arine sponge,
Spongia
sp.,
Svenzea
sp.,
Ircinia
sp., and
Igernella
sp. Of 68 isolates, 15
(22%) isolates had anti-
Vibrio
activities in various spectra against three
Vibrio
species, including
V. harveyi, V. parahaemolyticus
, and V. vulnificus.
All isolates producing anti-
Vibrio
compounds were non-haemolytic. Bacterial isolates
coded as D6.6, D6.19, and P4.17 have broad spectra.
They
could inhibit at least two
Vibrio
species as indicated by the clear zone formed arou
nd bacterial colonies. Based on 16S-rRNA, these iso
lates were
closely related (similarity ≥ 99%) to
Brevibacterium casei
strain M Sw oHS,
Bacillus altitudinis
strain FJAT 47750, and
Bacillus altitudinis
strain
PgBe190, respectively. D6.6 isolate was the most po
tential isolate, which could inhibit three
Vibrio
species. Consistently, its anti-
Vibrio
activity also
confirmed by their supernatant, concentrated cultur
e, and crude extract of that isolate. The crude ext
ract derived from this isolate contained 10
major compounds that are biologically active.
Conclusion
:
This study suggests that 15 bacteria strains isolat
ed from marine sponges were potentially could inhib
it
Vibrio
’s growth
in vitro
. These
isolate could be further explored as anti-
Vibrio
agent.