ISOLATION AND IDENTIFICATION OF BACILLUS ALCALOPHILUS FROM KAPPAPHYCUS ALVAREZII AND THEIR ANTIBACTERIAL ACTIVITY AGAINST HUMAN PATHOGENSSYAHARUDDIN, ASNAH MARZUKI, SUDIR SUMARHENI AND YAYU M. EVARYAbstract Bioactive compounds from algae-associated bacteria are good resources for fulfilling necessity of antibiotics which are used for many kinds of infectious diseases. A study was performed to determine the influence of alkaline and glucose concentrated medium condition to the growth of Bacillus alcalophilus and its activity to produce bioactive compounds as antibiotic agents. Bacillus alcalophilus was isolated and purified from red algae K. alvarezii and the identification of isolates was conducted using PCR amplification. The active isolate from antagonist test was fermented for ten days to produce secondary metabolites. The highest amount of B. alcalophilus isolate was obtained after 10 days of fermentation with optical density 0.691. The inhibition zone, minimum inhibitory concentration (MIC) and minimum killing concentration (MKC) were measured to determine the antibiotic activity. Two extraction methods were designed to collect the secondary metabolites. The First was extracted with ethyl acetate and showed activity against Staph. aureus and E.coli with the inhibition zone of 9.7 mm and 8.20 mm, respectively. While the other part of the supernatant was absorbed with active carbon and extracted with acetone. The acetone extract was showed antibiotic activity against S. Aureus with the inhibition zone of 11.56 mm (at a concentration of 9%) and 8.38 mm against B. subtilis. Phytochemical screening of secondary metabolites was done by using Thin Layer Chromatography (TLC) plates and showed positive reaction to sitroboric reagents and expected to be a flavonoid group compounds. These inventions suggest that B. alcalophilus may contribute to the search for new antibiotic compounds.
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