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Microbiological Analysis of Iron‐Related Biofouling in Water Wells and a Flow‐Cell Apparatus for Field and Laboratory Investigations
Author(s) -
Tuhela Laura,
Smith Stuart A.,
Tuovinen Olli H.
Publication year - 1993
Publication title -
groundwater
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.84
H-Index - 94
eISSN - 1745-6584
pISSN - 0017-467X
DOI - 10.1111/j.1745-6584.1993.tb00872.x
Subject(s) - biofouling , biofilm , microorganism , ferrihydrite , precipitation , environmental chemistry , chemistry , bacteria , mineralogy , geology , biochemistry , membrane , meteorology , paleontology , physics , organic chemistry , adsorption
A flow‐cell assembly was constructed to collect biofilm samples on glass slides in an effort to monitor Fe‐precipitating microorganisms in water wells. The flow‐cell was used with a once‐flow‐through connection to municipal‐water wells which had previous histories of Fe‐related precipitation and biofouling problems. Microscopic observations of biofilms attached to glass slides confirmed the presence of stalked and sheathed bacteria believed to be involved in Fe (III)‐precipitation. Scanning electron microscopy confirmed that biofilm samples contained Gallionella ‐type morphological features composed of helical, intertwisted stalks. Attempts to recover these organisms with cultural methods were unsuccessful. For monitoring Fe‐precipitating microorganisms, a differential solid medium was developed from the general‐purpose heterotrophic platecount medium (R2A) by incorporating ferric ammonium citrate in the formulation. Organisms capable of using citrate in the modified medium yielded rust‐colored colonies due to the formation of Fe (III)‐precipitates. These Fe‐precipitating bacteria did not possess stalks, sheaths, or other appendages, and their presence could not be predicted from microscopic examination of the sample materials. Optical measurement of biofilm thickness was deemed unreliable because of large variation in the thickness of Fe(III)‐precipitation and associated bacterial attachment. Fe(III)‐precipitates were identified as ferrihydrite, a poorly crystalline Fe(III)‐oxide. Laboratory studies with amended well‐water samples recirculating through a flow‐cell were used to enrich for organisms involved in biofouling communities. These experiments yielded methylotrophic organisms capable of growing with methanol and methylamine, and they were classified as Hyphomicrobium spp.