Selective isolation and antagonistic activity of actinomycetes from mangrove forest of Pahang, Malaysia

Abstract

This study aimed to isolate and evaluate the antagonistic potential of actinomycetes from mangrove forest of Pahang, Malaysia. Sediment samples from seven different sites were pretreated using wet heat and dry heat methods followed by dilution plating on eight isolation media. In total, 4850 isolates were successfully recovered, with inorganic salt-starch agar displaying the highest percentage of recovery (31.7%), followed by actinomycete isolation agar (24.1%). The wet heat pretreatment was found to be more effective in the enumeration of actinomycetes, since 81.4% of total isolates were yielded using this technique, whereas dry heat treatment was better in the enumeration of spore-forming actinomycetes. After both pretreatments, Streptomyces-like and Micromonospora-like isolates were the most predominant. The antagonistic activities of the representative isolates were evaluated using the cross-streak method. In total, 78 isolates were active against at least one of the test organisms. Among them, 28.2% exhibited antibacterial activity, 23.1% exhibited antifungal activity and 48.7% displayed both. Nine isolates demonstrated broad antagonism by inhibiting the growth of all test organisms. The presence of a relatively large number of bioactive isolates suggests that Pahang mangrove forest is a potential source of actinomycetes with biosynthetic capabilities.

CHEMICAL COMPONENTS OF POLYMERASE CHAIN REACTION IN 18S rRNA FOR DETECTION OF Cryptosporidium FROM RIVER WATER SAMPLES

“…Reduced concentration of polymerases ensure specificity while higher counterpart causing nonspecific amplicons [19]. DNA polymerases are favored in PCR process with a cofactor like magnesium ion [20]. They are easily manipulated resulting in the stringency of PCR as its ionic concentration is critical.…”

First molecular characterization of Cryptosporidium from three different points of two main rivers in Kuantan, Malaysia using 18S rRNA gene nested PCR

“…This is could be due to the fact that the location of downstream and midstream point of Balok River is near to residential areas whereby the housing discharge from residential areas might be dumped to Balok River from the nearby housing drains. In particular, downstream point of Balok River is also near to mangrove forest area that might increase the probability of getting Cryptosporidium oocysts on surface river water even this area is also adjacent to estuary of Balok River heading to South China Sea [19]. In fact, the upstream point of Balok River is also located near to forest area where zoonotic transmission of Cryptosporidium oocysts can possibly happen and infect nearby river water stream [19].…”

“…In particular, downstream point of Balok River is also near to mangrove forest area that might increase the probability of getting Cryptosporidium oocysts on surface river water even this area is also adjacent to estuary of Balok River heading to South China Sea [19]. In fact, the upstream point of Balok River is also located near to forest area where zoonotic transmission of Cryptosporidium oocysts can possibly happen and infect nearby river water stream [19]. In contrast, only one water sample from the upstream point of Kuantan River was detected to be negative for C. parvum.…”

Antimicrobial Activity of Marine Actinomycetes and the Optimization of Culture Conditions for the Production of Antimicrobial Agent(s)

“…1). However, several previous studies reported lower percentages of antagonistic isolates among actinomycetes isolated from marine environments [17][18][19] . Only 2 isolates (12.5%) did not exhibit any antimicrobial activity against any of the pathogens tested.…”