Evaluation of toxic effects of aeration and trichloroethylene oxidation on methanotrophic bacteria grown with different nitrogen sources

Journal Article · Mon Feb 01 04:00:00 EST 1999 · Applied and Environmental Microbiology

OSTI ID:330550

Chu, K H; Alvarez-Cohen, L ^[1]

---

1. Univ. of California, Berkeley, CA (United States). Dept. of Civil and Environmental Engineering

In this study the authors evaluated specific and nonspecific toxic effects of aeration and trichloroethylene (TCE) oxidation on methanotrophic bacteria grown with different nitrogen sources (nitrate, ammonia, and molecular nitrogen). The specific toxic effects, exerted directly on soluble methane monooxygenase (sMMO), were evaluated by comparing changes in methane uptake rates and naphthalene oxidation rates following aeration and/or TCE oxidation. Nonspecific toxic effects, defined as general cellular damage, were examined by using a combination of epifluorescent cellular stains to measure viable cell numbers based on respiratory activity and measuring formate oxidation activities following aeration and TCE transformation. Their results suggest that aeration damages predominantly sMMO rather than other general cellular components, whereas TCE oxidation exerts a broad range of toxic effects that damage both specific and nonspecific cellular functions. TCE oxidation caused sMMO-catalyzed activity and respiratory activity to decrease linearly with the amount of substrate degraded. Severe TCE oxidation toxicity resulted in total cessation of the methane, naphthalene, and formate oxidation activities and a 95% decrease in the respiratory activity of methanotrophs. The failure of cells to recover even after 7 days of incubation with methane suggests that generation of greater amounts of sMMO per cell due to nitrogen fixation may be responsible for enhanced TCE oxidation activities of nitrogen-fixing methanotrophs rather than enzymatic protection mechanisms associated with the nitrogenase enzymes.

• OSTI ID: 330550
• Journal Information: Applied and Environmental Microbiology, Journal Name: Applied and Environmental Microbiology Journal Issue: 2 Vol. 65; ISSN AEMIDF; ISSN 0099-2240
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
56 BIOLOGY AND MEDICINE
APPLIED STUDIES
AERATION
BIODEGRADATION
CHLORINATED ALIPHATIC HYDROCARBONS
GROWTH
METHANOTROPHIC BACTERIA
NITROGEN FIXATION
TOXICITY