Relating Chloroethene Respiration Rates in Dehalococcoides to Protein and mRNA Biomarkers

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• 作者：Annette R. Rowe ; Gretchen L. Heavner ; Cresten B. Mansfeldt ; Jeffrey J. Werner ; Ruth E. Richardson
• 刊名：Environmental Science & Technology (ES&T)
• 出版年：2012
• 出版时间：September 4, 2012
• 年：2012
• 卷：46
• 期：17
• 页码：9388-9397
• 全文大小：512K
• 年卷期：v.46,no.17(September 4, 2012)
• ISSN：1520-5851

文摘

Molecular biomarkers could provide critical insight into myriad in situ microbial activities. In this study we explore correlations of both mRNA and protein biomarkers with chloroethene respiration rate in Dehalococcoides. In a series of continuously fed dechlorinating mixed-culture microcosm experiments (n = 26), we varied respiratory substrates, substrate ratios and feeding rates. Transcript levels for most biomarkers were responsive down to 0.01脳 the culture鈥檚 maximum respiration rate. The dehalogenase TceA and the Ni鈥揊e hydrogenase HupL transcripts were positively correlated (Pearson鈥檚 r of 0.89 and 0.88, respectively) with respiration rates on log鈥搇og plots between 1.5 and 280 渭eeq/L-hr for mRNA abundances of 10⁷ to 10¹⁰ transcripts/mL (0.07鈥?30 transcripts/genome). These trends were independent of the types of chloroethene or electron donors fed. Other mRNA target levels plateaued or declined at respiration rates above 5 渭eeq/L-hr. Using both relative and absolute protein quantification methods, we found that per-genome protein abundances of most targeted biomarkers did not statistically change over the experimental time frames. However, quantified enzyme levels allowed us to calculate in vivo enzyme-specific rate constants (kb>catb>) for the dehalogenases PceA and TceA: 400 and 22 substrate molecules/enzyme-sec, respectively. Overall, these data support the promise of both mRNA and protein biomarkers for estimating process rates through either empirical (mRNA-based) or kinetic (protein-based) models, but they require follow-up studies in other cultures and at active remediation sites.