Isolation of polyhydroxyalkanoate producing bacteria from brackish water surrounding Bakau Tinggi, Kemaman

Abstract

This study was conducted to evaluate the potential production of polyhydroxyalkanoate (PHA) by bacteria isolated from water sample of mangrove environment in Bakau Tinggi, Kemaman, Terengganu. A total of 134 bacteria colonies isolated anq screened using Nile red staining in order to observe the potential PHA producer. A total of 15 colonies when glucose used as a carbon source and 6 colonies when fructose used as a carbon source was observed to emit pink fluorescence when viewed under UV light. This indicates the probable present of PHA granules in those bacteria. There are possibilities where the Nile red staining was only indicates the present of fatty acid in bacteria cell. Shaken-flasks culture with nutrient limitation and addition of excess carbon sources (glucose, fructose, cooking oil, oleic acid) resulting on the growth of bacteria strain in medium supplemented with glucose and fructose. However, no growth observed in medium supplemented with cooking oil and oleic acid. This phenomenon probably occurred due to the different ability of the bacteria to synthesize and utilize the carbon sources supplement for growth or PHA production. The result of gas chromatography indicates the production of MCL-PHA by strain R6(-6)50.1 using glucose as a carbon source. MCL-PHA produced consist a monomer of 3-hydroxydodecanoate (C12) and 3-hydroxytetradecanoate (C14) with a total PHA content of 2.8 wt%. The strain was tested as gram-negative by using Gram staining method. The complete identification of bacteria species by using Polymerase Chain Reaction (PCR) is proposed on the future study.