Investigations into the biodegradation of microcystin-LR mediated by the biofilm in wintertime from a biological treatment facility in a drinking-water treatment plant.
The potential of winter biofilm for microcystin-LR (MCLR) biodegradation was comparatively evaluated under various nutrient conditions. Results indicated that MCLR was completely biodegraded by Day 7 without nutrient addition. MCLR-biodegradation was inhibited in the presence of phosphate or glucose addition, with complete MCLR removal observed by Day 10. MCLR was totally biodegraded by Day 7 with dual nutrients comprising glucose and nitrate, suggesting that additional nitrate alleviated the inhibitory effect of glucose alone on the biodegradation. Simultaneously, MCLR-degrading gene (mlrA) abundance were detected to increase with increasing amount of MCLR being degraded under the respective conditions, implying that MCLR-biodegradation depended on the population of indigenous MCLR-degrading bacteria (MCLRDB), which was related to the population of non-degrading bacteria in the biofilm. MCLRDB was found to primarily use MCLR for proliferation rather than other nutrients. This is the first report verifying MCLR as a primary substrate for bacteria under various nutrient conditions.
Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan. lijie.ming@hotmail.com
Jieming
J
Li
Kazuya
K
Shimizu
Hideaki
H
Maseda
Zhijiang
Z
Lu
Motoo
M
Utsumi
Zhenya
Z
Zhang
Norio
N
Sugiura
D001419:Bacteria / Q000235:genetics; D001673:Biodegradation, Environmental; D018441:Biofilms; D004275:DNA, Ribosomal / Q000235:genetics; D060766:Drinking Water / Q000382:microbiology*; D005798:Genes, Bacterial / Q000235:genetics; D006863:Hydrogen-Ion Concentration; D008387:Marine Toxins; D052998:Microcystins / Q000302:isolation & purification / Q000378:metabolism*; D012621:Seasons; D013997:Time Factors; D018508:Water Purification / Q000379:methods*
D004275:DNA, Ribosomal; D060766:Drinking Water; D008387:Marine Toxins; D052998:Microcystins; C057862:cyanoginosin LR