Antivibrio compounds produced by Pseudomonas sp. W3: characterisation and assessment of their safety to shrimps

Abstract

In order to explore compounds naturallly inhibitory to shrimp pathogenic vibrios, a culture filtrate of Pseudomonas sp. W3 at a pH of 2 was extracted with ethyl acetate (EtOAc) to produce 82.15 mg/l of a yellow-brown extract (EtOAc-W3) that had MIC values of 225-450 lg/ml against the growth of 18 shrimp pathogenic Vibrio harveyi strains. The MIC of EtOAc-W3 against the most pathogenic strain PSU 2015 was 450 lg/ml and this strain had the lowest LD 50 (50% lethal dose) to pacific white shrimp (Litopenaeus vannamei, PL 21). At this MIC value, EtOAc-W3 in artificial sea water (ASW) killed strain PSU 2015; however in natural sea water, only a partial growth inhibition was observed. The toxicity to pacific white shrimp and antivibrio activity of the EtOAc-W3 were investigated by conducting an experiment with 4 sets; native control (commercial ASW), EtOAc-W3 control (MIC/10, 45 lg/ml), challenge (inoculation 6.0 9 10 6 c.f.u./ml PSU 2015) and treatment (6.0 9 10 6 c.f.u./ml PSU 2015 ? 45 lg/ml EtOAc-W3). The same experiment was repeated by increasing the dose of EtOAc-W3 to 90 lg/ml (MIC/5). Both concentrations of EtOAc-W3 tested had no toxicity to postlarval shrimps. A significant decrease in shrimp mortality was observed over a 72 h period as approximately 80% of the shrimps died in each challenge set but only 63 and 23% died in the presence of 45 and 90 lg/ml EtOAc-W3. The major component of EtOAc-W3 was supposed to be 2-heptyl-4-quinolone (HHQ) by FAB-MS and 1 H-NMR analyses of the purified fraction.

In vitro and in vivo selection of probiotic purple nonsulphur bacteria with an ability to inhibit shrimp pathogens: acute hepatopancreatic necrosis disease-causing Vibrio parahaemolyticus and other vibrios

“…It is well recognized that most of the bacteria that cause pathogenic infections of shrimp are Vibrio spp. (Rattanachuay, Kantachote, Tantirungkij, Nitoda & Kanzaki , ). The use of antibiotics for shrimp farming is not recommended for controlling disease (Serrano ; Albuquerque‐ Costa, Araujo, Souza & Vieira ) because of the potential to build up antibiotic resistant strains in the sediments (Defoirdt, Sorgeloos & Bossier ).…”

Pyocyanin induced in vitro oxidative damage and its toxicity level in human, fish and insect cell lines for its selective biological applications

“…However, the in vitro toxicity studies and the IC 50 value of pyocyanin from environmental isolates in various biological systems including human cell lines have yet to be accomplished. Antagonistic Pseudomonas species are gaining increasing attention as biological control agents for pathogenic fungi and bacteria in agriculture (Anjaiah et al 2003;Bano andMusarrat 2003, Rangarajan et al 2003;Kumar et al 2005), vibrios in aquaculture (Chythanya et al 2002;Rattanachuay et al 2011) and also as augmenters in bioremediation programs (De Meyer et al 1999;Chaerun et al 2004;Hasanuzzaman et al 2004;Tang et al 2007). Considering the above applications and to facilitate its safe usage toxicity of purified pyocyanin from an environmental isolate of P. aeruginosa (MCCB 118) has been tested on human, fish and insect cell lines chosen based on its possible exposure to handlers (humans) and the very sensitive aquatic (fish) and terrestrial (insect) systems as representatives.…”

Antagonistic effect of Pseudomonas aeruginosa isolates from various ecological niches on Vibrio species pathogenic to crustaceans

“…The isolates of Pseudomonas were grown in the above mentioned media and incubated at (28依1) °C . About 1 mL aliquot of each of these 24 h grown Pseudomonas cultures were removed, centrifuged at 12 000 r/min for 15 min and 20 µL supernatant was spotted onto sterile discs of 6 mm in diameter (prepared from a stack of 6 Whatman No.1 filter papers) and placed on the plates swabbed with Vibrio spp. The plates were incubated at (28依1) °C for 18 h and the diameter of the zone of inhibition recorded using HI antibiotic zone scale (Himedia, Mumbai, India).…”

“…Differences in the diameter of the inhibition zones were related to the quantity of pyocyanin produced by each isolate grown at different salinities. For all the isolates, maximum inhibition zones were obtained when they were grown in media at [5][6][7][8][9][10] g/L salinity and the marine isolate MCCB117 could inhibit vibrios even when grown at a salinity of 40 g/L. …”

“…Among the probiotics, antagonistic Pseudomonas spp. have been gaining increasing attention as biological control agents against pathogenic fungi and bacteria in agriculture [2][3][4] , vibrios in aquaculture [5,6] and also as bioaugmenters in bioremediation programs [7][8][9] . Specifically, the versatile and ubiquitous bacterium, Pseudomonas aeruginosa [10,11] ( P. aeruginosa ) has recently been recognized as an active antagonist of pathogenic Vibryo harveyi (V. harveyi) and thus as a candidate probiotic in aquaculture systems [12][13][14][15] .…”