In vitro screening of, antibacterial antifungal and cytotoxicity activities in crude extract of freshwater cyanobacterium Oscillatoria sp.

Authors: Manoj Wijesekara & Pathmalal Manage
Journal: Journal of Tropical Forestry and Environment

Cyanobacteria, highly diverse group of prokaryotes are recognized as a potent source of biologically active compounds with antiviral, antibacterial, antifungal, and anticancer properties.The aim of the present study was to screen antibacterial, antifungal and cytotoxic activities of intracellular secondary metabolites of freshwater cyanobacterium Oscillataria sp. Cyanobacterium Oscillatoria sp. was isolated from Senanayaka Samudraya reservoir (70 11’ 37.370N 810 31’ 47.130E), Sri Lanka.In vitro antibacterial and antifungal activity of Oscillatoria sp. was screened against Gram-positive Methicillin-resistant Staphylococcus aureus (MRSA) ATCC 25923, Bacillus anthracis and Gram-negative Pseudomonas aeruginosa (ATCC 25853), Salmonella typhi and Escherichia coli (ATCC 25922) and fungi, unicellular Candida albicans (ATCC 60192) and Candida tropicalis using agar disc diffusion method.The Minimum Inhibitory Concentrations (MIC), Minimum Bacteriocidal Concentration (MBC), Minimum Fungicidal Concentrations (MFC) and cytotoxic effects (brine shrimp bioassay) of Oscillatoria crude extract were determined. 10% and 60% of biomass was extracted with hexane and methanol respectively.Gas Chromatography-Mass Spectrometry (GC-MS) was used to identify compounds in the crude extract. The highest antibacterial and antifungal activity of crude extract were detectedin methanol extract against S.aureus (19 ± 2 mm)and C.albicans (10 ± 1 mm) within 24 hours wherein the hexane extract, antibacterial activity was detected only for S. aureus and mean diameter of inhibition zone was 11 ± 1mm within 24 hours.The lowest MIC of methanol extract against S. aureus wasfound as 156.25 μg/ml. The lowest MBC and MFC of methanol extract againstS. aureus and C.albicans were 0.63 mg/ml and 1.25mg/ml respectively. Lethal concentration, 50% of the crude extract against brine shrimp was recorded at 2.50 g/l, 1.25 g/l and 0.625 g/l for 6, 12, 24 hrs intervals respectively. GC-MS analysis revealed that the methanol crude extract of Oscillatoria sp. contains important fatty acid namely hexadecanoic acid methyl ester, methyl tetradecane and 13-tetradecanoic acid and n-hexane extract contains Bis (2-ethylhexyl hydroxypyridine oxide, 1 2-benzenedicarboxylic acid mono (2-ethylhexyl) ester, Phthalic acid 6-ethyl-3-Octyl heptyl ester and Phthalic acid dodecyl nonyl ester which may possess antibacterial and antifungal properties.



Degradation of Microcystin LR, Oxytetracycline and Amphicillin by Four Native Bacteria Species

Authors: PS Dharmadasa, GY Liyanage, PM Manage
Journal: Journal of Tropical Forestry and Environment

Pollution reaches its most serious proportion in past few decades and adversely effect on animals and human health. Reduction of pollutant in the environment take place with microbial metabolism and remediation studies by microbes have proved their feasibility on clean up the contaminated environment. Thus, the present study reports the biodegradation of Micocystins (MC-LR) and antibiotics [Oxytetracycline (OTC) and Ampicillin (AMP)] by Bacillus cereusEnterobacter ulcerans, Enterobacter sp. and Micrococcus sp. strains which were previously reported as potential crude oil degraders.  A 0.5 ml of overnight starved bacterial suspensions was introduced into medium containing antibiotic (OTC, AMP) at 60 µg/ml and Microcystin-LR at 10 µg/ml respectively. Triplicate samples were incubated at 280C while shaking at 100 rpm. A 0.5 ml of aliquots was removed at 2 days interval for a period of 14 days and analysis was done by High Performance Liquid Chromatography (HPLC). The highest degradation of MC- LR was shown by Micrococcus sp. (97%) where as other stains; E. ulcerans (96 %), Enterobactor sp. (95 %) and B. cereus (88%) also showed comparative high degradation after 14 days of incubation. B. cereusEnterobacter sp. and Micrococcus sp. were identified as AMP resistance bacteria and degraded AMP at 81%, 22% and 39% respectively. It was found that B. cereus was resistance to OTC and showed 56% reduction at 14 days of incubation. The results of the present study revealed that the bioremediation potential of harnessing microbes can cleanup of pollutant in the environment and use as eco friendly tool for removal of environmental pollutants.


වෙල්ඩින් කර්මාන්තය හා පොලික්ලොරිනේටඩ් බයිෆීනෝල්, පාරිසරික සහ මානව සෞඛ්‍ය බලපෑම්

සත්ත්ව විද්‍යා අධ්‍යයන අංශ ප්‍රධානී, මහාචාර්ය පත්මලාල් මානගේ මහතා විසින් 2017 දෙසැම්බර් 13 වන දින විදුසර විද්‍යා සගරාවේ පලකළ විශේෂ ලිපිය.

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