Isolation and Characterization of Four Gram-PositiveNickel-Tolerant Microorganisms from Contaminated Riparian Sediments

• Published in: Microbial ecology 2006-08, Vol.53 (3)
• Main Authors: Van Nostrand, Joy D., Khijniak, Tatiana V., Gentry, Terry J., Novak, Michelle T., Sowder, Andrew G., Zhou, Jizhong Z., Bertsch, PaulM, Morris, Pamela J.
• Format: Article
• Language: English
• Subjects: ANTIBIOTICS; BACTERIA; Bioremediation, Extremophiles, Field Studies, StressResponse; COMMUNITIES; FUNCTIONALS; GENES; HOMEOSTASIS; MICROORGANISMS; PROBES; SEDIMENTS; STREPTOMYCES; TELLURIUM; TOLERANCE
• ISSN: 0095-3628; 1432-184X

Microbial communities from riparian sediments contaminatedwith high levels of Ni and U were examined for metal-tolerantmicroorganisms. Isolation of four aerobic Ni-tolerant, Gram-positiveheterotrophic bacteria indicated selection pressure from Ni. Theseisolates were identified as Arthrobacter oxydans NR-1, Streptomycesgalbus NR-2, Streptomyces aureofaciens NR-3, and Kitasatosporacystarginea NR-4 based on partial 16S rDNA sequences. A functional genemicroarray containing gene probes for functions associated withbiogeochemical cycling, metal homeostasis, and organic contaminantdegradation showed little overlap among the four isolates. Fifteen of thegenes were detected in all four isolates with only two of these relatedto metal resistance, specifically to tellurium. Each of the four isolatesalso displayed resistance to at least one of six antibiotics tested, withresistance to kanamycin, gentamycin, and ciprofloxacin observed in atleast two of the isolates. Further characterization of S. aureofaciensNR-3 and K. cystarginea NR-4 demonstrated that both isolates expressed Nitolerance constitutively. In addition, both were able to grow in higherconcentrations of Ni at pH 6 as compared to pH 7 (42.6 and 8.5 mM Ni atpH 6 and 7, respectively). Tolerance to Cd, Co, and Zn was also examinedin these two isolates; a similar pH-dependent metal tolerance wasobserved when grown with Co and Zn. Neither isolate was tolerant to Cd.These findings suggest that Ni is exerting a selection pressure at thissite for metal-resistant actinomycetes.