Diversity of Culturable Bacteria from Talang-talang reef and its surrounding waters
Felicity W.I. KUEK1*, Aazani MUJAHID2, Po-Teen LIM2, Chui-Pin LEAW3, Moritz MÜLLER1 1
School of Engineering, Computing and Science, Swinburne University of Technology, Sarawak campus, 93350 Kuching, Sarawak, Malaysia. 2 Department of Aquatic Science, Faculty of Resource Science and Technology, Universiti Malaysia Sarawak, 93400 Kota Samarahan, Sarawak, Malaysia. 3 Institute of Biodiversity and Environmental Conservation, Universiti Malaysia Sarawak, Kota Samarahan, 94300 Sarawak, Malaysia. *Corresponding e-mail:
[email protected]
STUDY AREA
MAIN AIM To isolate, identify and determine the diversity of culturable bacteria from coral surface, surface mucus layer, sediment and its surrounding waters.
INTRODUCTION The reefs of Sarawak are limited to the areas off the shores of Bintulu, Miri and offshore islands including the Talang-Satang region in Kuching. The Talang-talang islands are situated off the coast of Sematan and are especially important as they are one of the most diverse ecosystems found off Sarawak. The isolation and identification of native microbes from the coral surface, surface mucus layer, sediment and surrounding waters allows us to determine the species composition and abundance of various bacteria in the coral reef environment through culture- and molecularbased approaches. This is the first description of the microbial communities associated with corals in Sarawak, Malaysia.
METHODOLOGY
Figure 1: Partial map of Sarawak, depicting the sampling sites of Talang-talang Islands, located approximately 10nm from the coasts of Sematan.
Corals
Water
RESULTS & DISCUSSION
Sediment
Mucus isolates
Unknown Alteromonadales Unknown 3% Alphaproteobact
eria 5%
Spreading of mucus, water and dilute onto agar plates
Coral mucus
Brachybacterium 2%
Unknown bacteria 5%
Table 1: Summary of bacterial communities in coral mucus, water and sediment
Halomonas 2%
Bacillus 10%
Klebsiella 5% Kocuria 5% Microbulbifer 3% Photobacterium 3% Psychrobacter 3% Roseobacter 5% Sphingobium 3%
Vibrio 46%
Serial dilution Incubation at room temperature (30°C)
Unknown Vibrionaceae 9%
A) Overview of bacterial communities at Talang -talang reef
Number of isolates Dominant species Number of unknown isolates Species of interest
Water isolates Alteromonas 9%
Isolation of bacteria
Halomonas 27%
Vibrio 37%
DNA isolation and PCR amplification using universal bacterial 16s rDNA primers (8F and 519R)
Unknown Vibrionaceae 7%
Sediment isolates
Unknown Alteromonadales 5%
Sent for sequencing at the Beijing Genomic Institute Gel electrophoresis
DNA purification
Bacillus 9%
Water
Sediment
39
11
43
Vibrio sp., Bacillus sp.
Vibrio sp., Halomonas sp.
Vibrio sp., Bacillus sp.
5
1
7
Vibrio coralliilyticus, Roseobacter sp.
None
Vibrio shiloi
Vibro sp. dominates in all ecosystems. V. coralliilyticus and V. shiloi are both known coral pathogens, playing a role in coral bleaching[1] [2]. Roseobacter sp. has been found to be closely associated with phytoplankton blooms, and members of this group utilize [3] dimethylsulfoniopropionate (DMSP) .
B) Difference in coral mucus isolates
Lysinibacillus 9%
Rhodobacter 9%
Coral mucus
Unknown bacteria 5%
Ferrimonas 2% Lysinibacillus 5%
Coral mucus isolates are the most diverse (11 genera). 90% of isolates found attached to corals are potentially pathogenic Vibrio sp.. Bacteria isolated from the coral surface mucus layer (SML) are more diverse and have potential roles in coral defence, nitrogen fixing[4] and DMS production.
C) Antibacterial properties Vibrio 67%
Figure 2: Phylogenetic groups of isolates from coral mucus, water and sediment.
20-30 % of bacterial isolates originating from coral SML may possess antibacterial properties that can assist the coral holobiont as a first line of defence[5]. It has been suggested that these antimicrobial compounds are temperature sensitive[6]. Antibacterial screening is currently being conducted and isolates that exhibit antibacterial properties will undergo temperature tests.
Acknowledgement The authors wish to thank the Sarawak Forestry Corporation for permission to conduct sampling at the Talang-Satang National Park, Sarawak. This study is partially funded by the Sarawak Foundation under the Tunku Abdul Rahman Scholarship.
CONCLUSIONS 1) Vibrio sp. is the most dominant bacteria isolated from all three ecosystems. 2) Coral mucus has the most diverse number of isolates, followed by sediment and water. 3) Two known coral pathogens were isolated from the reef environment: Vibrio coralliilyticus from coral mucus and Vibrio shiloi from sediment. 4) Mucus isolates have potential antibacterial properties and may be involved in DMS production. Further research is on-going. 5) Unknown isolates are related to uncultured bacteria or have very low hits on BLAST. They may potentially be new bacteria.
References: [1]
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