Preliminary characterization of a Nisin Z bacteriocin with activity against the fish pathogen Streptococcus iniae

Wright, Emily E., Nguyen, Hong Uyen, and Owens, Leigh (2017) Preliminary characterization of a Nisin Z bacteriocin with activity against the fish pathogen Streptococcus iniae. Oceanography & Fisheries, 3 (2). pp. 1-13.

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Abstract

This is a preliminary characterisation of a bacteriocin, BacL49 produced by Lactococcus lactis ssp. lactis. This bacteriocin is significant due to its activity against Streptococcus iniae, a bacterial pathogen causing severe economic losses in the global aquaculture of various fish. Spot-on-lawn and microtitre plate assays were used to test antagonistic activity of the bacteriocin. BacL49 is heat and pH stable (100 °C for 60min, pH 2.5-9.5), and sensitive to proteinase K, α-chymotrypsin, trypsin and papain. BacL49 has a bactericidal mode of action and is produced during late log phase growth. BacL49 exhibits a broad activity spectrum against S. iniae, antagonising 93.75% (45/48) of S. iniae isolates collected from a variety of hosts and environments. The apparent molecular masses of the active protein components determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis are 5 and 54kDa. Molecular analyses were performed to locate the genetic determinants of BacL49. PCR of chromosomal DNA successfully amplified the structural gene encoding the precursor of nisin. Subsequent analysis of nucleotide sequences of the PCR products revealed it to be identical to the nis Z structural gene of nisin Z. There is a paucity of reports examining the inhibition of S. iniae by a lactococcal bacteriocin or even L. lactis as an aquacultural probiotic. This is one of the first studies to identify nisin genes in a strain of L. lactis exhibiting activity against S. iniae. BacL49 is a candidate biocontrol agent for mitigation of this important fish pathogen.

Item ID: 49656
Item Type: Article (Research - C1)
ISSN: 2476-0536
Keywords: bacteriocin; Lactococcus lactis; probiotic; Streptococcus iniae; Nisin Z
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This work is licensed under Creative Commons Attribution 4.0 Licence.

Funders: James Cook University (JCU)
Date Deposited: 25 Jul 2017 01:30
FoR Codes: 06 BIOLOGICAL SCIENCES > 0605 Microbiology > 060501 Bacteriology @ 50%
07 AGRICULTURAL AND VETERINARY SCIENCES > 0704 Fisheries Sciences > 070404 Fish Pests and Diseases @ 50%
SEO Codes: 83 ANIMAL PRODUCTION AND ANIMAL PRIMARY PRODUCTS > 8301 Fisheries - Aquaculture > 830102 Aquaculture Fin Fish (excl. Tuna) @ 100%
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