In vitro assessment of potential probiotic characteristics of indigenous Lactococcus lactis and Weissella oryzae isolates from rainbow trout (Oncorhynchus mykiss Walbaum)

• Published in: Journal of applied microbiology Vol. 129; no. 4; pp. 1004 - 1019
• Main Authors: Mortezaei, F., Royan, M., Allaf Noveirian, H., Babakhani, A., Alaie Kordghashlaghi, H., Balcázar, J.L.
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 01-10-2020
• Subjects: Acid resistance; Animals; Antibiotics; Antiinfectives and antibacterials; Antimicrobial activity; Aquaculture; Bacteria; Bacteria - drug effects; Bile salts; Biosafety; Fish; Fish Diseases - microbiology; fish pathogens; Gastrointestinal Microbiome; Gene sequencing; Hydrophobicity; indigenous microbiota; Intestinal microflora; Intestine; Lactic acid; Lactic acid bacteria; Lactococcus lactis; Lactococcus lactis - isolation & purification; Lactococcus lactis - physiology; Microbiota; Oncorhynchus mykiss; Oncorhynchus mykiss - microbiology; Pancreatin; probiotic characteristics; Probiotics; Probiotics - isolation & purification; Probiotics - pharmacology; rainbow trout; RNA, Ribosomal, 16S - genetics; rRNA 16S; Salmon; Salts; Sodium chloride; Temperature; Trout; Virulence; Virulence factors; Weissella; Weissella - isolation & purification; Weissella - physiology; Weissella oryzae; Lactococcus lactis; indigenous microbiota; rainbow trout; Weissella oryzae; probiotic characteristics; biosafety; fish pathogens
• ISSN: 1364-5072; 1365-2672
• DOI: 10.1111/jam.14652

Aim
The objective of this study was to evaluate the probiotic potential of lactic acid bacteria (LAB) isolated from the intestinal ecosystem of rainbow trout.
Methods and Results
Among LAB isolates, 10 of them were selected and screened for resistance to acid and bile salts, pancreatin, sodium chloride and temperature, hydrophobicity, growth profile and antimicrobial activity against fish pathogens. Then, biosafety assessments were investigated. Selected LAB tolerated to gastrointestinal physiological conditions, pancreatin and a range of sodium chloride and temperature. They also exhibited hydrophobicity and showed antagonistic activity against Streptococcus iniae and Yersinia ruckeri. Results of 16S rRNA gene sequencing showed that selected LAB belonged to the Lactococcus lactis (n = 5) and Weissella oryzae (n = 5) species. They exhibited no β‐haemolytic activity, while six selected LAB were resistant to some antibiotics. None of them harboured virulence factors.
Conclusions
This study revealed probiotic characteristics of indigenous LAB isolated from the intestinal ecosystem of rainbow trout. However, further studies are required to confirm the effectiveness of these isolates as probiotics in aquaculture.
Significance and Impact of the Study
To the best of our knowledge, for the first time, the presence of probiotic candidates belonging to W. Oryzae was confirmed in fish intestinal microbiota.