Study of antibacterial effect of Lysozyme on Streptococcus iniae and Lactococcus garviea isolated from rainbow trout (O.mykiss) in Chaharmahal-o-Bakhtiari province

Subject Areas : Food-Borne Diseases

Masomeh Mohammady ¹ , Amin Nematollahi ² , Hamdollah Moshtaghi ³ , Mojtaba Bonyadian ⁴

1 - دانش‌آموخته کارشناسی ارشد بهداشت آبزیان، دانشکده دامپزشکی، دانشگاه شهرکرد، شهرکرد، ایران.
2 - گروه بهداشت و کنترل کیفی مواد غذایی ،دانشکده دامپزشکی، دانشگاه شهرکرد، شهرکرد، ایران.
3 - گروه بهداشت و کنترل کیفی مواد غذایی ،دانشکده دامپزشکی، دانشگاه شهرکرد، شهرکرد، ایران.
4 - گروه بهداشت و کنترل کیفی مواد غذایی ،دانشکده دامپزشکی، دانشگاه شهرکرد، شهرکرد، ایران.

Received: 2017-04-22 Accepted : 2017-11-29 Published : 2018-01-21

Keywords: Rainbow trout, Streptococcus iniae, Lactococcus garviea, Lysozyme,

Abstract :

The Streptococcus iniae and lactococcus garviea bacteria cause both Streptococcosis and Lactococcosis diseases in the fishes and so in humann. In recent years, these two factors had large break out in fish-breeding farms. This study amid to verify the effect of lysozyme concentration on Streptococcus iniae and Lactococcus bacteria .It also determined minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of these compounds on the growth of mentioned bacteria. Present study investigated antimicrobial effect of different concentrations of Lysozyme (5000, 2500, 1250, 625, 312.5, 156.25, 78.13, 89.06 and 19.53 µg/mL) against Streptoccus iniae and Lactococcus garviea isolated from rainbow trout in Chaharmahal-o-Bakhtiary province. The study used the methods of light (optical) absorption and microdilution in three pH including 5.5, 6, 7, as well. The result of microdilution showed the effect of lysozym in the inhibition of the growth of both bacteria at pH 5.5 and 6 on concentration of 5000 µg/ml, whereas, at pH7 was observed any inhibition. The results showed declining light absorption values resulting from the growth of both bacteria with increasing concentration of lysozyme, however the inhibition effect of 5000 µg/ml of lysosyme at pH6 and 5.5 was significantly (p<0.05) less, in comparison with the smaller concentrations. On the other hand, any inhibitory effect as the optical absorption was observed in the growth of bacteria for the highest concentration of lysozyme in the media of pH 7.