Awang, Mohd Syafiq
(2018)
Discovery Of Antibacterial-Producing
Actinobacteria From Selected Malaysian
Mangrove Sediments.
Masters thesis, Universiti Sains Malaysia.
Abstract
The rapid emergence of multi-drug resistant pathogenic bacteria has called for
intensive research on the discovery of new and potent antibacterial metabolites.
Actinobacteria is one of the major producers of antibacterial secondary metabolites.
Among the most reliable sources for the isolation of actinobacteria are forest soil and
marine sediments. Mangrove is a rich marine environment, but it is seldom explored
for actinobacterial isolation. Accordingly, the present study was carried out with the
main aim to isolate and screen for potential antibacterial-producing actinobacteria
from mangrove sediments. The mangrove sediments were sampled from the
mangrove environment located at Balik Pulau, Pulau Pinang, Malaysia. A total of
131 actinobacterial isolates were successfully isolated by using a combination of
selective pre-treatment and isolation media. Preliminary screening of these isolates
against five species of Gram-positive and Gram-negative bacteria using cross streak
plate method showed that 54 % of the isolates were capable of producing
antibacterial metabolites. Among these active isolates, 70 % have broad-spectrum
antibacterial activity against both Gram-positive and Gram-negative test bacteria,
24 % have narrow-spectrum antibacterial activity against only Gram-positive
bacteria and 6 % against only Gram-negative test bacteria. Five actinobacterial
isolates with potent broad-spectrum antibacterial activity were selected for
cultivation in three litres submerged culture fermentation using a bubble-column
bioreactor.
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