Enumeration and characterization of culturable arsenate resistant bacteria in a large estuary

• Published in: Systematic and applied microbiology 2005-10, Vol.28 (8), p.727-734
• Main Authors: Jackson, C.R., Harrison, K.G., Dugas, S.L.
• Format: Article
• Language: English
• Subjects: Animal, plant and microbial ecology; Aquatic bacteria; Arsenate-resistant bacteria; Arsenates - pharmacology; Arsenic; Arsenic resistance; Bacteria - classification; Bacteria - drug effects; Bacteria - growth & development; Bacteria - isolation & purification; Bacteriology; Biodiversity; Biological and medical sciences; Colony Count, Microbial; Dose-Response Relationship, Drug; Drug Resistance, Bacterial; Estuary; Flavobacteriaceae - classification; Flavobacteriaceae - drug effects; Flavobacteriaceae - growth & development; Flavobacteriaceae - isolation & purification; Fundamental and applied biological sciences. Psychology; Louisiana; Microbial ecology; Microbiology; Miscellaneous; Molecular Sequence Data; Proteobacteria - classification; Proteobacteria - drug effects; Proteobacteria - growth & development; Proteobacteria - isolation & purification; RNA, Bacterial - genetics; RNA, Ribosomal, 16S - genetics; Species Specificity; Various environments (extraatmospheric space, air, water); Water Microbiology; Water Pollution
• ISSN: 0723-2020; 1618-0984
• DOI: 10.1016/j.syapm.2005.05.012

Arsenic is a toxic element that exists in two major inorganic forms, arsenate and arsenite. A number of bacteria have been shown to resist arsenic exposure, and even more bacteria appear to possess the genes for arsenic resistance. In this study, the numbers of culturable arsenate-resistant bacteria present in water at three coastal sites in the Lake Pontchartrain estuary, Louisiana, was determined. Despite insignificant (less than 1.33 μM) levels of arsenic in this system, 20–50% of the viable count of bacteria showed appreciable arsenate resistance, suggesting that arsenic-resistant bacteria are common and widespread. A diverse array of arsenate-resistant isolates was obtained, with 16S rRNA sequence analysis indicating 37 different bacterial strains, representing six major bacterial groups. Many of these isolates were affiliated with groups of bacteria that have been poorly characterized in terms of arsenic resistance, such as the Betaproteobacteria or Flavobacteria. Some isolates were capable of tolerating very high (>100 mM) levels of arsenate, although arsenite resistance was generally much lower. The results suggest that arsenic-resistant bacteria are common, even in environments with insignificant arsenic contamination, and that many different groups of aquatic bacteria show appreciable arsenic resistance.