Properties of Probiotics Kocuria SM1 and Rhodococcus SM2 Isolated from Fish Guts

S. M. Sharifuzzaman*, Hafizur Rahman, Dawn Amy Austin, B. Austin

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

26 Citations (Scopus)


This study characterized probiotics Kocuria SM1 and Rhodococcus SM2, which were recovered from the intestinal microbiota of rainbow trout (Oncorhynchus mykiss, Walbaum). The cultures were Gram-positive, non-motile, catalase-positive and oxidase-negative cocci or rods. Cell multiplication of SM1 and SM2 was observed at 4–37 °C (45 °C for SM1), in 0–20% (w/v) NaCl and at pH 2–11. The viability was not affected when exposed to pepsin at pH 2.0 and 3.0, and pancreatin at pH 8.0. Neither isolates were chrome azurol S-positive for siderophore production. Of the 19 common enzymes analysed using the API-ZYM system, only 8 were evident in the culture of SM1 compared to 11 enzymes for SM2. The secondary metabolites of both probiotics were inhibitory to Acinetobacter baumannii, Vibrio anguillarum and V. ordalii; SM2 inhibited Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Staphylococcus aureus. SM2 was resistant to penicillin and sulphatriad, out of six antimicrobial agents; SM1 was resistant to sulphatriad. These results suggest that Kocuria SM1 and Rhodococcus SM2 are able to grow over a wide range of temperature, salinity and pH, including in conditions that mimic the gastrointestinal environment of fish and produce extracellular enzymes that may have a role in the host digestive processes. Importantly, Rhodococcus SM2 displays a high degree of bacteriocinogenic potential against multi-drug-resistant human pathogens that have never been documented among the gut microbiota of fish.

Original languageEnglish
Pages (from-to)1-9
Number of pages9
JournalProbiotics and Antimicrobial Proteins
Early online date5 Jun 2017
Publication statusE-pub ahead of print - 5 Jun 2017


  • Antagonism
  • Antibiogramme
  • Identification
  • Intestinal microbiota
  • Probiotics
  • Rainbow trout

ASJC Scopus subject areas

  • Microbiology
  • Molecular Medicine
  • Molecular Biology


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