Vibriosis caused by Vibrio alginolyticus infection is getting challenging to treat as the bacteria harbor the ability to form biofilm. One of the natural products that might be potentially applied to treat vibriosis through biofilm deformation is the leaves of Moringa oleifera. The objective of the study was to determine the effect of ethanol extracts of M. oleifera to inhibit V. alginolyticus biofilm formation in vitro. A microtiter plate biofilm assay (OD570nm) method was applied in this study. The treatments were the addition of ethanolic Moringa leaves extracts at different concentrations of 2%, 4%, 8% and 10%. The result of this study showed that Moringa leaves extract significantly inhibited the biofilm formation of V. alginolyticus. The optimal condition to inhibit biofilm formation was at 10% concentration for 60 hours incubation at room temperature signifying the potential application of Moringa leaf extracts to treat biofilmmediated diseases in aquaculture.

Abstract. Suhartono S, Ismail YS, Muhayya SR. 2019. The interference of Moringa oleifera leaf extracts to modulate quorum sensing-facilitated virulence factors. Biodiversitas 20: 3000-3004. The infections attenuated by the presence of virulence factors might be facilitated by quorum sensing (QS) mechanism. The continuous treatments of bacterial infections with current drugs, however, has developed such pathogenic bacteria more antibiotic-resistant, encouraging to searching for better alternative treatment, such as the use of plant-derived bioactive constituents, including kelor (Moringa oleifera L.). In the present research, kelor (M. oleifera) ethanolic leaf extract was evaluated for their potency as an antibacterial agent to inhibit bacterial virulence factors mediated by quorum sensing mechanism against Chromobacterium violaceum and Pseudomonas aeruginosa PAO1. A phytochemical examination of M. oleifera leaf-ethanolic extracts has been conducted resulting positive detection of alkaloids, steroids, terpenoids, flavonoids, and phenolics or tannins. The extracts had MIC and MBC values of 10 mg/mL and 20 mg/mL, respectively, for both tested bacteria. The ethanolic extracts of M. oleifera leaves also showed potent inhibition of quorum sensing by significantly reducing violacein and pyocyanin production as well as interference of swarming motility and biofilm formation.

Vibriosis is one of the major problems in prawn aquaculture leading to a significant loss in yield. The objective of the study was to isolate and identify the etiological agent of vibriosis from the giant freshwater prawn (Macrobrachium rosenbergiii) aquaculture. The study was conducted by isolating the bacteria using selective media of thiosulfate-citrate-bile salts-sucrose (TCBS) agar followed by the morphological and biochemical characterizations, i.e., indole, methyl-red (MR), Voges-Proskauer (VP), citrate, urease, NaCl 0%, gelatinase and lysine decarboxylase tests. The isolated bacteria were further assayed for their standard growth-curve as well as the ability to form a biofilm on Congo-red agar (CRA). The results showed that the bacteria showed a yellow color in colony appearance and had negative Gram staining. On the biochemical assays, the isolates showed positive reactions on the indole, MR, VP, gelatine, and lysine decarboxylase; but had negative reactions on the citrate, urea, and NaCl 0% tests. The isolates were then identified as Vibrio alginolyticus and after further characterization, the isolates showed the ability to form a biofilm. This result signifies the urgency to overcome V-. alginolyticus as the causing agent of vibriosis that was able to form a biofilm on the giant river prawn aquaculture.