Subcellular components of probiotics Kocuria SM1 and Rhodococcus SM2 induce protective immunity in rainbow trout (Oncorhynchus mykiss, Walbaum) against Vibrio anguillarum

Abstract

The efficacy of cellular components of probiotics Kocuria SM1 and Rhodococcus SM2 to protect rainbow trout (Oncorhynchus mykiss, Walbaum) against vibriosis was assessed. Groups of fish (average weight = 10–15 g) were immunized intraperitoneally (i.p.) with 0.1 ml of subcellular materials, i.e. 0.2 ± 0.05 mg protein per fish, comprising extracellular proteins (ECPs), cell wall proteins (CWPs) and whole cell proteins (WCPs) of SM1 and SM2, respectively, or with 0.1 ml of phosphate-buffered saline (PBS) to serve as the control. Seven days after administration, fish from each group were challenged i.p. with 0.1 ml of a suspension in PBS of 3 × 105 cells ml−1 per fish of Vibrio anguillarum. Use of CWPs and WCPs demonstrated significantly (P < 0.05) better protection against V. anguillarum insofar as mortalities were reduced to 11–17% [relative percent survival (RPS) = 80–87%], although ECPs fared less well (mortalities = 33–38%; RPS = 56–62%; P > 0.05), compared to 86% mortalities of the controls. The mode of action reflected activation of innate immune factors by CWPs and WCPs, demonstrating significantly (P < 0.05) increased expression of respiratory burst (optical density; OD550nm) from 0.039 to 0.043–0.045, peroxidase (OD550nm) from 0.26 to 0.37–0.55, and bacterial killing activities (i.e. percentage of surviving bacteria reduced from 79% to 56–57% for SM2). Moreover, an elevation of leucocyte number (from 1.93% to 1.98–2.93%; P > 0.05) and immunoglubolin level (from 27 mg ml−1 to 28.5–33 mg ml−1; P > 0.05) were observed with the experimental groups. These results indicate that cell components of the probiotics stimulate an immune response

Role of Bacillus licheniformis VS16-Derived Biosurfactant in Mediating Immune Responses in Carp Rohu and its Application to the Food Industry

“…It is used to identify and neutralize foreign objects such as bacteria and viruses (Giri et al, 2014). Similarly, cellular components of the probiotics Kocuria SM1 and Rhodococcus SM2 increased IgM levels in Oncorhynchus mykiss (Sharifuzzaman et al, 2011). Earlier studies demonstrated that probiotic supplementation increased IgM levels in fish at an initial time point; however, at later time points, these levels declined (Sun et al, 2010; Giri et al, 2013, 2014).…”

“…Recently, the application of probiotics has also received attention in aquaculture. However, one concern regarding its uses is antagonism with other beneficial bacteria, the possible development of virulence traits through horizontal gene transfer, and pathogenicity to humans (Sharifuzzaman et al, 2011). The limitations of antibiotics, chemotherapeutics, vaccines, and probiotics suggest that aquaculture disease management should emphasize on harmless, preventative, and lasting methods.…”

Use of bacterial subcellular components as immunostimulants in fish aquaculture

“…One of the uncertainties surrounding the usage of probiotics is that the release of live bacterial cells in large quantities into the vicinity of fish could interfere with the associated eco‐systems (Sharifuzzaman et al . ). Additionally, there is concern regarding potential antagonism with other beneficial bacteria, possible development of virulence traits through horizontal gene transfer and the pathogenicity to humans (Sharifuzzaman et al .…”

“…Additionally, there is concern regarding potential antagonism with other beneficial bacteria, possible development of virulence traits through horizontal gene transfer and the pathogenicity to humans (Sharifuzzaman et al . ). For example, the risk of lateral gene transfer of antibiotic resistance genes has raised questions regarding the use of Streptomyces as probiotic in aquaculture (Tan et al .…”

“…Thus, the administration of bacterial subcellular components, especially those of probiotics, might eliminate potential concerns associated with virulence (Sharifuzzaman et al . ). Bacterial cell components such as lipopolysaccharides (LPS) from Gram‐negative bacteria, lipoteichoic acid (LTA) and peptidoglycan (PGN) from Gram‐positive bacteria, and bacterial DNA have been reported as potent immunostimulants for fish (MacKenzie et al .…”