Arsenic resistant microorganisms isolated from agricultural drainage water and evaporation pond sediments
✍ Scribed by K. Davis Huysmans; W. T. Frankenberger
- Book ID
- 104646174
- Publisher
- Springer Netherlands
- Year
- 1990
- Tongue
- English
- Weight
- 561 KB
- Volume
- 53
- Category
- Article
- ISSN
- 0049-6979
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✦ Synopsis
Elevated levels of As in contaminated water and soil could pose a major threat to the environment. Relatively high levels of As have been reported in agricultural drainage water and in evaporation pond sediments in Kern County, California. The objective of this study was to enumerate and isolate Asresistant microorganisms from agricultural drainage water and evaporation pond sediments and to assess their tolerance to metals, metalloids and antibiotics. The culture medium was amended with arsenite (III), arsenate (V), methylarsonic acid (MAA), and dimethylarsinic acid (DMA). Among the water samples, As(V), MAA, and DMA added to the medium at concentrations from 0.1 to 1000 mg L -~ showed no effect on the colony forming units (CFUs) compared with no As supplementation, while arsenite (III) (> 1.0 mg L -1) inhibited the population. The sediments showed three trends: (i) no effect on CFUs in the presence of As(V) up to 1000 mg kg -1, (ii) a decline in CFUs in the presence of > 100 mg kg -1 As(III), and (iii) an increase in CFUs upon the addition of MAA or DMA at > 25 mg kg -~. Arsenite (III) was much more toxic to the indigenous microflora than any other As species. Arsenite (III) inactivates many enzymes by having a high affinity for thiol groups of proteins. A plate diffusion method was used to assess the tolerance of the As-resistant bacteria to heavy metals, metalloids and antibiotics. Of 14 isolates tested, all were resistant to Co, Cu, Pb, Ni, Mo, Cr, Se(IV), Se(VI), As(III), As(V), Sb, Sn, and Ag (50 v,g mL-1). The most toxic trace elements were Cd followed by Hg>Te>Zn. Multiple antibiotic tolerance (resistance to 2 or more antibiotics) was found among 43% of the isolates. The As-resistant bacteria showed a high tolerance to metals and antibiotics.