El-Sharouny, EE; Belal, MA; Yusef, HH
Two psychrotolerant bacteria were isolated from Nile river, Egypt during winter 2007. Based on 16S rRNA sequences, they were identified as members of the genus Kocuria.The yellow pigmented strain showed 99% similarity to K.carniphila, and was designated as K. carniphila MY, whereas the orange strain was similar to Kocuria Polaris by 99% and was named K.polaris MO. Both strains grew best at pH 7.2. The optimum growth temperature was found to be 28°C and 20°C for K.carniphila MY and K.polaris MO, respectively. The two strains shared the same need to glycerol, fructose, glucose, xylose, mannose, cellulose, cyclohexane and benzene as carbon sources. Casein and peptone supportrd maximal growth, whilst inorganic nitrogen sources (NaNO3, (NH4)2SO4 and NH4Cl) proved to be unsuitable for both strains.The two strains could tolerate high level of salinity reaching up to 7.5% and 10% NaCl for K.carniphila MY and K.polaris MO, respectively.They were sensitive to the tested antibiotics; Salbactam+ampicillin, Ceftazidim, Amikin, Ofloxacin, Kanamycin, Ceftriaxone, Chloramphenicol, Cefotaxim, Cefadroxil, Aztreonam, Cefalexin and Tetracycline and were resistant to nitrofurantoin, nalidixic acid and colistin.The metabolized cells of the isolates were used for metal biosorption, where it was noticed that K.carniphila MY and K.polaris MO highly biosorbed all of the five tested cations (Zn, Cu, Co, Cd, and Pb) with maximum affinity towards Zn and Cu, respectively.