| dc.description.abstract | Sponge has been acknowledged for its ability to produce secondary
metabolites compounds that have been explored for new source of marine natural
product compounds. Unfortunately, information on sponge ecological interaction,
especially concerning its secondary metabolite production and symbiotic
organisms, are usually from observation and experimental researches in coral
reefs ecosystem. Meanwhile, not many information has been gathered on sponge
community and its ecological interaction in the seagrass ecosystem.
Information on sponge community and its ecological interaction in seagrass
ecosystem should be explored intensively, for seagrass vegetation could has
different environmental condition due to seagrass species characterization that
composing the ecosystem. Thus, vegetation characterization of seagrass will
influence sponge community and its secondary metabolite, and also its interaction
with symbiotic microbial (bacterial). This research wants to figure out several
issues concerning sponge community in seagrass ecosystem. These issues are:
will sponge species composition and association be different due to condition of
seagrass vegetation in the ecosystem; is sponge species in seagrass ecosystem
have the same potential concerning its antibacterial activity as in reefs area; how
diverse the sponge bacterial symbiont and the potential of its secondary
metabolite; and also how the ecological interaction between sponge and its
symbiotic bacterial.
This research was conducted in several stages. The first stage is field
observation at seagrass ecosystem. The next stage was conducted as laboratory
activities. Laboratory activities were conducted in several phases. The phase was
an assay to test the antibacterial activity of sponges tissues on generally tested
bacteria (Escherichia coli and Staphylococcus aureus) and marine bacteria
isolates from surrounding water (Al1, Al2, Al3, Al4 and Al5). The aims of this
activity were to screen potential sponge that having antibacterial activity, and
isolating its symbiotic bacterial. Afterwards, the next phase was an assay to test
the antagonistic activity of sponge symbiotic bacterial against marine-biofilm
forming bacteria. Symbiotic bacterial with high antagonistic activity then
analyzed for its species diversity, using molecular analysis of symbiotic bacterial
DNA fingerprinting and identification.
Field observation was done in two different seagrass meadow/bed in
Pramuka Island, Seribu Islands, near Jakarta Bay, Indonesia, since September
2013 to Mei 2014. Laboratory assays activities were done in Marine Microbiology
Laboratory and Marine Biosystematics and Biodiversity, Departement of Marine
Science and Technology, Bogor Agricultural University (IPB). Antibacterial assay
on sponge tissue was conducted since September 2013 to March 2014, whilst
isolation on symbiotic bacterial and secondary metabolites assay were done from
December 2013 to November 2015. Molecular analysis on bacterial symbionts
diversity and identification were just done ons January to May 2016.
Results of this research showed that sponge community in seagrass
ecosystem was influenced by the density, morphological form and vegetation
architectural of seagrass beds. Sponge will have more species number (higher
diversity), with lower abundance in patchy seagrass bed. On the contrary,
diversity of sponge will be lower, with higher individual number (abundance) in
continuous seagrass bed, regarding higher protection mechanism from predatory
activities in continuous bed. Overall, sponge community at both seagrass beds
(Site 1 and 2) were dominated by Spirastrella sp. (Sp) and Agelas conifera
sponges.
Antibacterial assay showed that only 7 of 18 sponge species have low
activity against pathogenic bacteria (E. coli and S. aureus) and marine bacteria
from surrounding water. This probably caused by a conducive environment
condition for sponge growth and less environmental stress that could stimulate
sponge antibacterial activity.
There were 44 different colonies of bacterial symbionts successfully isolated
from 9 species of sponge, with 22 active isolates against potential marine biofilmforming
bacteria. The higher number of bacterial symbionts was isolated from
Haliclona spp. (Hy), Iotrochota sp. (Io) and Aplysina aerophoba, respectively.
The antagonistic activity of those 22 symbiotic bacteria has the similar
interaction with all targeting bacteria. It showed that all those 22 isolates of 44
symbiotic bacteria isolates have similar activity and antibiofilm potential. This
high antibiofilm activity also promising for the search of biofilm modulator
compounds that has important values in medicines. The most promising symbiotic
bacteria (Aa3) was came from Aplysina aerophoba sponge, with higher activity
(more than 9 mm inhibition zone) against 4 marine biofilm-forming bacteria,
respectively.
Genomic fingerprinting analysis of symbiotic bacteria was used Rep-PCR
method. It showed that symbiotic bacteria from same species of sponge have close
genetic relation than bacteria from different species of sponges. Nevertheless,
DNA sequencing result showed that there was genomic homologous of several
bacterial groups from different sponges. 16sDNA sequencing resultsof 12
symbiotic bacteria isolates showed that those bacteria has genomic homologous
with α and γ proteobacteria and firmicutes bacterial groups.
Ecologically, symbiotic interaction between bacterial symbionts and
sponges is a protection mechanism against marine-biofilm forming bacteria for
sponge, that was contributed by the symbiotic bacteria, despite sponge
antibacterial activity was very low. It’s related with the activation mechanism of
sponge chemical defense that need adequate stimulus, such as space competition
and/or predation activity by other organisms. | id |
