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Articles by Gires Usup
Total Records ( 4 ) for Gires Usup
  Fatemeh Shayesteh , Asmat Ahmad and Gires Usup
  Antibacterial peptides have emerged as an alternative therapeutic to protect food and other products from deterioration and spoilage. In this study, bacteria were isolated from marine clams and screened for bacteriocin production using cross-streaking and spot-on-lawn methods. One of the isolates, identified as Bacillus species Sh10, produced proteinaceous bacteriocin with a broad spectrum of activity against human pathogens and food-spoilage bacteria. The effect of different media compositions and culture conditions namely, the type and concentration of carbon and nitrogen source, NaCl concentration, temperature, pH, aeration and incubation time on the production of bacteriocin by Bacillus sp. Sh10 was investigated. Optimum bacteriocin production was recorded when 2% tryptone and 1% glucose were added to a basal medium as nitrogen and carbon sources, respectively. The bacteria exhibited maximum bacteriocin production at 2% NaCl, pH 8, 30°C and 200 rev min-1 aeration. Bacteriocin was produced during the stationary phase, indicating it is synthesized as a secondary metabolite. Bacillus sp. Sh10 is able to produce bacteriocin at a wide pH and temperature range making it a good candidate for the production of bacteriocin on an industrial scale level.
  Mohammad Mokhtari , Mazlan Abd Ghaffar , Gires Usup and Zaidi Che Cob
  Fiddler crabs burrow creates oxic-anoxic interfaces on the burrow walls. Accordingly burrow walls represent the transitions site between oxic and anoxic condition where the sediment properties varied significantly across it. In this study the burrows of three species of fiddler crabs including Uca rosea, Uca forcipata and Uca pardussumieri were sampled at three depth layers. Sediment properties of burrow walls including; temperature, redox potential, pH, density, porosity, water content, organic content, chlorophyll content and solid phase iron pools were measured to determine the magnitude of burrow effects on mangrove sediments. The results indicated that U. paradussumieri effectively reduced the sediment porosity of surrounding sediments down to 45%. Oxidized layer was more extended around U. paradussumieri burrows. Burrow walls of U. forcipata and U. paradussumieri contain higher water content than ambient sediment and burrows of U. rosea efficiently decreased the organic content of sediment. The PCA biplots indicated that the burrow walls of the all three species of fiddler crabs at 3 and 8 cm depth were correlated with oxidized iron. Ambient sediments of U. forcipata habitat were correlated with reduced iron and organic content. At 20 cm depth, burrow walls of U. paradussumieri were highly correlated with water content, while ambient sediment was correlated with reduced iron. The results of this study revealed that the thickness of oxidized layer varied according to sediment depth and burrow volume. Consequently the burrow effect varied significantly among different species of fiddler crabs as results of different habitat characteristics, sediment types and crab size.
  K.D. Simon , A.G. Mazlan and Gires Usup
  Toxicity analysis of the puffer fishes Lagocephalus wheeleri and Lagocephalus sceleratus from the East Coast Water of Peninsular Malaysia was carried out. The presence of tetrodotoxin (TTX) in fish tissue and cultures of bacteria isolated from the liver of the fish were determined. Detection of TTX was carried out by mouse bioassay, Thin Layer Chromatography (TLC) and High Performance Liquid Chromatography (HPLC). The bacteria Shewanella sp. was isolated from the liver of L. wheeleri while, Exiguobacterium sp. and Staphylococcus sp. were isolated from the liver of L. sceleratus. Mouse bioassay showed that tissue extracts of L. wheeleri and culture supernatants of Shewanella sp. were positive for TTX. Tissue extracts of L. sceleratus and culture supernatants of Exiguobacterium sp. and Staphylococcus sp. exhibited non-lethal toxicity to mice but the symptoms were not typical of TTX poisoning. The symptoms in mice, coupled with TLC and HPLC analysis indicated that the toxic factor in L. wheeleri and Shewanella sp. was TTX. This study has confirmed the toxicity of the puffer L. wheeleri and some of this toxicity may be attributed to symbiotic bacteria.
  Muhd. Danish-Daniel , Mohd. Ezhar Mohd. Noor , Nur Azna Saari , Mohd. Huzairi Mohd. Zainudin , Yeong Yik Sung and Gires Usup
  Background: Association between bacteria and marine dinoflagellates is one of the important factors in harmful algae bloom formation and toxin production by dinoflagellates. The diversity of the bacteria associated with clonal cultures of both toxic and non-toxic dinoflagellates, Alexandrium tamiyavanichii and Alexandrium leei were assessed by using culture dependent and culture independent approaches. Materials and Methods: In culture-dependent approach, isolated bacteria were identified based on 16S rDNA sequences. In culture-independent approach bulk nucleic acid was extracted directly from the cultures of dinoflagellates. The extracted nucleic acid was then used for 16S rDNA amplification to construct the clone libraries. Nucleotide sequences obtained were then compared with sequences from the GenBank Database. Results: A total of 17 bacteria were isolated from culture of Alexandrium tamiyavanichii and 21 were from Alexandrium leei . The 16S rDNA sequences analysis revealed that bacteria associated with two species of dinoflagellates were a diverse group of α-proteobacteria (40%) followed by γ-proteobacteria and cytophaga flavobacter bacteroides (CFB) (21%) and firmicutes (14.7%). In 16S PCR cloning and sequencing analysis, a total of 50 phylotypes were obtained from the directly amplified DNA of both cultures, of which 22 phylotypes were obtained from Alexandrium tamiyavanichii and 28 from Alexandrium leei . Sequence analysis of the clones also revealed that associated bacteria belonged to α-proteobacteria (48.4%), CFB (21.2%), unknown bacteria group (18.9%) and γ-proteobacteria (10.5%). In addition, one phylotype belonged to Planctomycetes was discovered from culture of Alexandrium leei . The results suggest that a number of different bacterial species are associated with dinoflagellates, some of which are common to each of the dinoflagellate cultures examined, whereas others appear to be unique to a particular dinoflagellate. Conclusion: Present study showed that culture-independent method is necessary to capture better diversity of these associated bacteria since a large percentage of uncultured bacteria sequences were obtained.
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