Characterization of fermentation liquid from mangrove leaves Avicennia marina and its inhibitory potential for bacterium causing ice-ice disease

Abstract

ABSTRACT Fermentation liquid from mangrove leaves Avicennia marina contains microorganisms, nutrients, and secondary metabolites. This study aimed to identify bacteria and the compounds in fermentation liquid of mangrove leaves A. marina and measured their inhibitory capacity against pathogenic bacteria Stenotrophomonas maltophilia which causes ice-ice disease in seaweed. Molecular analysis which aimed the 16S rRNA gene showed that the bacteria in fermentation liquid consisted of eight types of Bacillus, Bacillus subtilis MSAR-01, Bacillus megaterium MSAR-02, Bacillus firmus MSAR-03, Bacillus thuringiensis MSAR-04, Bacillus subterranerus MSAR-05, Bacillus vietnamensis MSAR-06, Bacillus sp. MSAR-07, Bacillus circulans MSAR-08, with the best inhibitory power indicated by B. subtilis MSAR-01, B. vietnamensis MSAR-06, and Bacillus sp. MSAR-07. The administration of lactic acid, bacteriocin, total fermentation liquid, and supernatant as much as 15 mL produce inhibition to S. maltophilia indicated better result than using one or a combination of several types of bacterial isolates. The inhibition of single bacterial enriched fermentation and supernatant liquids was better than bacterial combination enrichment. Keywords: Avicennia marina, fermentation, ice-ice, mangrove