Identification and characterization of lactic acid bacteria isolated from rainbow trout, Oncorhynchus mykiss (Walbaum), with inhibitory activity against Lactococcus garvieae

Abstract

A study was conducted to evaluate the probiotic properties of endogenous rainbow trout microbiota against pathogenic Lactococcus garvieae. A total of 335 bacterial strains were isolated from rainbow trout and screened for antagonistic activity against L. garvieae using an agar spot assay. Antagonistic strains were grouped by PCR amplification of repetitive bacterial DNA elements (rep-PCR) and identified by 16S rRNA gene sequence analysis. The results revealed that the antagonistic strains belonged to the genera Lactobacillus, Lactococcus and Leuconostoc. Further probiotic characteristics, such as specific growth rate, doubling time, resistance to biological barriers, antibiotic resistance, hydrophobicity and production of antimicrobial substances, were also studied. These strains were able to survive low pH and high bile concentrations, showed good adherence characteristics and a broad spectrum of antibiotic resistance. The antagonistic efficacy was maintained after sterile filtration and was sensitive to proteinase K, indicating that proteinaceous extracellular inhibitory compounds were at least partially responsible for pathogen antagonism. Based on these results, these strains should be further studied to explore their probiotic effects in challenge experiments in vivo. This study shows clear evidence that the indigenous trout-associated microbiota may provide a defensive barrier against L. garvieae.

Garvicin A, a Novel Class IId Bacteriocin from Lactococcus garvieae That Inhibits Septum Formation in L. garvieae Strains

“…Usually, L. garvieae outbreaks in aquaculture are treated with antibiotics, but these are frequently ineffective, and their indiscriminate use is responsible for the appearance of antibiotic-resistant strains (1,52). To overcome the problems resulting from the emergence of antibiotic-resistant L. garvieae strains (1,52) and the limited number of antibiotics approved for use in aquaculture, several strategies, based mainly on the use of vaccines, probiotics, and bacteriocins, have been developed to fight lactococcosis (2)(3)(4).…”

“…To avoid the economic losses of fish lactococcosis, several strategies based on the use of vaccines, probiotics, or bacteriocins have been developed (2)(3)(4). However, the host range of L. garvieae is not limited to aquatic species; it has been associated with subclinical mastitis in cows and water buffalos (5,6) and with pneumonia in pigs (7).…”

A novel probiotic <i>Bacillus siamensis</i> B44v isolated from Thai pickled vegetables (<i>Phak-dong</i>) for potential use as a feed supplement in aquaculture

“…Several microorganisms have been evaluated as probiotics in aquaculture including lactic acid bacteria (Pérez-Sánchez et al, 2011), Bacillus (Han et al, 2015), actinobacteria (Das et al, 2010) and yeasts (Tovar-Ramirez et al, 2010). Thai fermented foods have been reported as potential sources of probiotic bacteria, such as Lactobacillus spp.…”

Antibiotics in Aquaculture – Use, Abuse and Alternatives

“…The most studied are lactic acid bacteria (LAB) (Lactobacillus, Carnobacterium, Enterococcus, Lactococcus, Micrococcus, Streptococcus, and Weissella) (Balcazar et al, 2008;Balcázar et al, 2007;Hagi & Hoshino, 2009;Pérez-Sánchez et al, 2011;Vazquez et al, 2005;Villamil et al, 2002), Bacillus (Ai et al, 2011;Antony et al, 2011;Balcázar & Rojas-Luna, 2007;Bandyopadhyay & Das Mohapatra, 2009;Ochoa-Solano & Olmos-Soto, 2006;Liu et al, 2009;Nakayama et al, 2009;Newaj-Fyzul et al, 2007;Olmos et al, 2011;Salinas et al, 2005;Sun et al, 2010;Vaseeharan & Ramasamy, 2003), Vibrio (Fjellheim et al, 2007;Thompson et al, 2010), Pseudomonas (Abd El-Rhman et al, 2009;Chythanya, 2002;Das et al, 2006;Preetha et al, 2007;Ström-Bestor, Wiklund, 2011), and Aeromonas (Irianto et al, 2003;Lategan et al, 2006;. Yeasts (Saccharomyces, Debaryomyces) (Abdeltawwab et al, 2008;Reyes-Becerril et al, 2008;Tovar-Ramírez et al, 2010), bacterial spore formers (Hong et al, 2005) and recently Actinobacteria have also generated interest due to their high metabolic potential (Das et al, 2010;You et al, 2007).…”