Antagonistic Activity of Cellular Components of Potential Probiotic Bacteria, Isolated from the Gut of Labeo rohita, Against Aeromonas hydrophila

Abstract

The objective of this study was to characterise the antagonistic activity of cellular components of potential probiotic bacteria isolated from the gut of healthy rohu (Labeo rohita), a tropical freshwater fish, against the fish pathogen, Aeromonas hydrophila. Three potential probiotic strains (referred to as R1, R2, and R5) were screened using a well diffusion, and their antagonistic activity against A. hydrophila was determined. Biochemical tests and 16S rRNA gene analysis confirmed that R1, R2, and R5 were Lactobacillus plantarum VSG3, Pseudomonas aeruginosa VSG2, and Bacillus subtilis VSG1, respectively. Four different fractions of cellular components (i.e. the whole-cell product, heat-killed whole-cell product [HKWCP], intracellular product [ICP], and extracellular product) of these selected strains were effective in an in vitro sensitivity test against 6 A. hydrophila strains. Among the cellular components, the ICP of R1, HKWCP of R2, and ICP of R5 exhibited the strongest antagonistic activities, as evidenced by their inhibition zones. The antimicrobial compounds from these selected cellular components were partially purified by thin-layer and high-performance liquid chromatography, and their properties were analysed. The ranges of pH stability of the purified compounds were wide (3.0-10.0), and compounds were thermally stable up to 90 °C. Considering these results, isolated probiotic strains may find potential applications in the prevention and treatment of aquatic aeromonosis.

Effects of dietary supplementation of potential probiotic Pseudomonas aeruginosa VSG-2 on the innate immunity and disease resistance of tropical freshwater fish, Labeo rohita

“…The potential probiotic bacterium P. aeruginosa VSG-2 was previously isolated from the gut contents of the tropical freshwater fish L. rohita [19]. The bacterium was grown in brain heart infusion broth for 24 h at 37 C. Cell density was calculated from OD 600 values and correlated with colony forming unit (cfu) counts using serial dilution and spread plating on tryptone soya agar (TSA).…”

“…However, the immunomodulatory effects of Pseudomonas aeruginosa on the major Indian carp L. rohita have not been reported. Recently, we isolated a potential probiotic, P. aeruginosa VSG-2, from the gut of the tropical freshwater fish rohu, L. rohita [19]. P. aeruginosa VSG-2 and its cellular components inhibit the growth of the fish pathogen A. hydrophila in vitro [19].…”

“…Recently, we isolated a potential probiotic, P. aeruginosa VSG-2, from the gut of the tropical freshwater fish rohu, L. rohita [19]. P. aeruginosa VSG-2 and its cellular components inhibit the growth of the fish pathogen A. hydrophila in vitro [19]. Furthermore, VSG-2 exhibits good tolerance to acid and bile, and adhesion to intestinal mucus [Unpublished data].…”

Identification and Biological Activity of Potential Probiotic Bacteria Isolated From Poecilia Reticulata (Guppy)

“…A good pool of candidate probiotics is of importance in the development of commercial probiotics in aquaculture. Bacteria in aquatic ecosystems might produce antimicrobial substances inhibiting the growth of other microorganisms (Giri et al, 2011). Selection of potential probiotic strains is based on many different criteria, such as acid and bile tolerance (tolerance to gastrointestinal environment), antagonistic activity against pathogens and survival in gastric juice.…”

The fish egg microbiome : diversity and activity against the oomycete pathogen Saprolegnia

“…Survival, immune responses (Balcázar et al, 2006;Balcázar et al, 2007b;Balcázar et al, 2007a;Luis Balcazar et al, 2007;Vendrell et al, 2008) Microbacterium Ruiz-Ponte et al, 1998;Ruiz-Ponte et al, 1999;Hjelm et al, 2004;Martens et al, 2006;Porsby et al, 2008;Kesarcodi-Watson et al, 2012;D'Alvise et al, 2013) (Gram et al, 1999;Vijayan et al, 2006;Gobeli et al, 2009;Hai et al, 2009;Aguilar-Macías et al, 2010;Pai et al, 2010;Campa-Córdova et al, 2011;Giri et al, 2011;Korkea-aho et al, 2011;Giri et al, 2012;Korkea-aho et al, 2012; Rhodopseudomonas Varela et al, 2010;<...>…”