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Title:	Isolation and identification of thermophilic photosynthetic bacteria and biological potentials of the bacteriocarotenoids
Authors:	Faith-Anthony Akinnuoye Olawale (P37289)
Supervisor:	Ainon Hamzah, Professor, Dr. (Datin)
Keywords:	Photosynthetic bacteria
Issue Date:	8-Jan-2013
Description:	The objectives of this study were to isolate thermophilic photosynthetic bacteria from hot spring, to determine the growth parameters for optimum bacteriocarotenoid production, to extract and identify bacteriocarotenoid properties from the selected bacterial isolates and to determine the bioactivities of the bacterial bacteriocarotenoid extracts. Initial isolation of hot spring samples from Pedas and Sungai Congkak, Malaysia was done using malate yeast extract (MYE) broth and MYE agar resulting in initial selection of 92 bacterial isolates. Eighteen isolates were finally selected for further identification based on colony pigmentation, thermophilic growth potential, pigment density, colony-forming units, and bacteriocarotenoid-producing capability with 14.2% and 8.3% phototrophic bacterial population from Pedas and Sungai Congkak respectively without significant statistical mean difference between the two locations. Morphological, biochemical, carbon source and microscopic examinations with structural analyses showed that the isolates were Gram-negative, motile, flagellated and belonged to six species of photosynthetic bacteria represented and identified as Rhodomicrobium vannielii (UKMP 4-5A), Rhodopseudomonas palustris (UKMP 2-5A), Blastochloris sulfoviridis (UKMSC 1-A2T), Rhodocista pekingensis (UKMP 3-4A), Rhodospirillum rubrum (UKMSC 1-A2) and Rhodocista centanaria (UKMP-WA). The growth of all the bacteria was optimal at pH 6.0-7.5, temperature of ≥ 45oC, light intensity of 1.5-2 kilo-lux except Blastochloris sulfoviridis and Rhodomicrobium vannielii (1.5 klux). Statistical evaluation of growth-enhancing parameters did show that the growth for all the isolates except B. sulfoviridis was optimised by agitation, pH, incubation time, temperature and by addition of 5 g/L yeast extract. Addition of methanol, ethanol, isopropyl alcohol, Dubai crude petroleum oil, and dimethylsulphoxide (DMSO) enhanced growth and bacteriocarotenoid yields of all the isolates except R. centanaria which did not metabolise ethanol. Bacteriocarotenoid production was optimised by varying the physical and nutritional parameters. Exo-structural, ultra-structural, and intra-cytoplasmic analyses by scanning and transmission electron microscopy revealed that the bacteria were rod or curved rod, ovoid. Polyhydroxybutyrate (PHB) was present in all the isolates as part of the intra-cytoplasmic inclusions while refractile body was found in two. Bacteriocarotenoid extracts were purified using thin layer chromatography (TLC), high performance liquid chromatography (HPLC) and TORFQ-HPLC methods. The spectra of the separated bacteriocarotenoids were determined by spectrophotometry method. Seven bacteriocarotenoid compounds were present. Three of the bacteriocarotenoids were identified as spirilloxanthin, rhodopin and β-carotene. Bioactivities of the identified compounds tested on MDA-MB, MCF-7, Hep-G2 (human carcinoma cell lines) and Vero (non-human cell line) for inhibitory ability showed the percentage of inhibition as 88.2, 78.9 and 81.2% respectively in cells treated with 25 μg/mL of identified bacteriocarotenoids incubated for 72 hours and 100% inhibition by crude extracts within 48 hours of exposure with necrosis at ≥ 25 μg/mL. Purified bacteriocarotenoids at 0.5-0.25 mL/2x106 cells and purified extracts at 0.126 mL/ 2x106cells did show mild toxicity on the Vero cell line. Ferric ion-reducing antioxidant power (FRAP) and 2,2-diphenyl-2-picrylhydrazyl (DPPH) assays showed anti-oxidative capability by all tested bacteriocarotenoids. Spirilloxanthin and rhodopin showed anti-oxidative potentials with less toxicity level in all the cells. Both inhibitions and antioxidative tests showed β-carotene to be more effective in most of the tested cell lines with weak biphasic response on cell line at 48 hours of exposure to the crude carotenoids and 72 hours of exposure to purified bacteriocarotenoids.,Phd
Pages:	263
Call Number:	QR88.5.F338 2013 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Science and Technology / Fakulti Sains dan Teknologi

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