Azam Sheida Doost - Young Researchers Club, Islamic Azad University-Lahijan Branch
Khosro Isazadeh - Department of Microbiology- Faculty of Basic Sciences, Islamic Azad University-Lahijan Branch
Mohammad Faezi Ghasemi

Introduction: Mycobacterium marinum is ubiquitous, slow growing nontuberculosis that has an optimal growth temperature at 30–32ºC. This organism can cause disseminated granulomatous infections in fish and other poikilothermic animals called ‘fish TB’. Changes of growth pattern is a strategy by which microorganisms survive in the face of a changing or hostile environment. The aim of study was evaluation of changes in nutritional and environmental factors on growth pattern and biofilm formation by M. marinum CCUG 20998.Materials and Methods: M. marinum CCUG 20998 was grown in Middlebrook 7H9 broth medium containing different concentrations of Tween 80 (50, 100, 150, 200, 250 and 300 μg/ml), Oleic Albumin Dextrose Catalase supplement (OADC), (2, 4, 6, and 8/ml) and glycerol (30, 35, 40, 45, and 50%). The growth patterns of this organism were measured at OD600 nm and compared to standard growth curve. Crystal violet staining method use for to evaluate the ability of biofilm formation.Results: The obtained results showed that M. marinum CCUG 20998 growth was maximum at 200 μg/ml of Tween 80. Oleic Albumin Dextrose Catalase supplement at different concentrations did not showed significant effect in increasing growth pattern of M. marinum CCUG 20988. Decreasing glycerol concentration significantly decreased growth rate of M. marinum CCUG 20998.Discussion: According to the results we can conclude that Tween 80 and glycerol in formulation of Middlebrook 7H9 broth are very critical for M. marinum CCUG 20998 growth. But in contrast Oleic Albumin Dextrose Catalase supplement can be omitted from medium formulation due to not very significant effect on growth pattern. The maximum biofilm formation was obtained in 35% glycerol without Tween 80 and OADC in culture medium.

Mycobacterium marinum CCUG 20998, environmental conditions, growth pattern, biofilm formation, Crystal violet staining method