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Biodegradation of microcystins during gravity-driven membrane (GDM) ultrafiltration.

Kohler E, Villiger J, Posch T, Derlon N, Shabarova T, Morgenroth E, Pernthaler J, Blom JF - PLoS ONE (2014)

Bottom Line: Presence of live or destroyed cyanobacterial cells in the feed water decreased the permeate flux in the Microcystis treatments considerably.At the same time, the microbial biofilms on the filter membranes could successfully reduce the amount of microcystins in the filtrate below the critical threshold concentration of 1 µg L(-1) MC for human consumption in three out of four replicates after 15 days.We found pronounced differences in the composition of bacterial communities of the biofilms on the filter membranes.

View Article: PubMed Central - PubMed

Affiliation: Limnological Station, Institute of Plant Biology, University of Zurich, Kilchberg, Switzerland.

ABSTRACT
Gravity-driven membrane (GDM) ultrafiltration systems require little maintenance: they operate without electricity at ultra-low pressure in dead-end mode and without control of the biofilm formation. These systems are already in use for water purification in some regions of the world where adequate treatment and distribution of drinking water is not readily available. However, many water bodies worldwide exhibit harmful blooms of cyanobacteria that severely lower the water quality due to the production of toxic microcystins (MCs). We studied the performance of a GDM system during an artificial Microcystis aeruginosa bloom in lake water and its simulated collapse (i.e., the massive release of microcystins) over a period of 21 days. Presence of live or destroyed cyanobacterial cells in the feed water decreased the permeate flux in the Microcystis treatments considerably. At the same time, the microbial biofilms on the filter membranes could successfully reduce the amount of microcystins in the filtrate below the critical threshold concentration of 1 µg L(-1) MC for human consumption in three out of four replicates after 15 days. We found pronounced differences in the composition of bacterial communities of the biofilms on the filter membranes. Bacterial genera that could be related to microcystin degradation substantially enriched in the biofilms amended with microcystin-containing cyanobacteria. In addition to bacteria previously characterized as microcystin degraders, members of other bacterial clades potentially involved in MC degradation could be identified.

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Related in: MedlinePlus

Cell abundances in the filtrate.Regrowth of bacterial single cells (upper panel), flagellates (middle panel) and flagellate-inedible bacterial aggregates (lower panel) in the filtrate of the three different treatments (LMA, DMA, and CON according to Figure 1).
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pone-0111794-g004: Cell abundances in the filtrate.Regrowth of bacterial single cells (upper panel), flagellates (middle panel) and flagellate-inedible bacterial aggregates (lower panel) in the filtrate of the three different treatments (LMA, DMA, and CON according to Figure 1).

Mentions: Bacterial single cell numbers in the CON filtrates constantly increased during the course of the experiment (Figure 4, upper panel) up to 0.1 and 0.3×106 cells mL−1, respectively. Similarly, flagellate and bacterial aggregate numbers increased slowly, but stayed on comparable low mean levels of 280 flagellates mL−1 and 78 aggregates mL−1 on day 21 of the experiment (Figure 4). In contrast, both MC treatments showed higher cell numbers as compared to the CON treatment. Between 0.8 and 0.5×106 bacterial single cells mL−1 were found in both replicates of the LMA treatment at the end of the experiment. Comparable numbers of bacterial single cell numbers were determined also in the replicate 1 of the DMA treatment (0.4×106 mL−1). The bacterial single cell numbers in the corresponding second replicate of the DMA treatment were about ten times higher (3.9×106 mL−1). Flagellate numbers in the filtrates of the LMA treatment were comparable high at the end of the experiment (mean value 0.67×104 mL−1), as well as bacterial aggregates (mean value 0.8×103 mL−1). Comparable numbers of flagellates were found in the filtrate of the first replicate of the DMA treatment (0.54×104 mL−1) as well as the highest amount of aggregates (4.0×103 mL−1) at the end of the experiment. However, rather low numbers of flagellates and aggregates were found in the second replicate of the DMA treatment, 0.15×104 mL−1 and 0.1×103 mL−1, respectively (Figure 4).


Biodegradation of microcystins during gravity-driven membrane (GDM) ultrafiltration.

Kohler E, Villiger J, Posch T, Derlon N, Shabarova T, Morgenroth E, Pernthaler J, Blom JF - PLoS ONE (2014)

Cell abundances in the filtrate.Regrowth of bacterial single cells (upper panel), flagellates (middle panel) and flagellate-inedible bacterial aggregates (lower panel) in the filtrate of the three different treatments (LMA, DMA, and CON according to Figure 1).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4219780&req=5

pone-0111794-g004: Cell abundances in the filtrate.Regrowth of bacterial single cells (upper panel), flagellates (middle panel) and flagellate-inedible bacterial aggregates (lower panel) in the filtrate of the three different treatments (LMA, DMA, and CON according to Figure 1).
Mentions: Bacterial single cell numbers in the CON filtrates constantly increased during the course of the experiment (Figure 4, upper panel) up to 0.1 and 0.3×106 cells mL−1, respectively. Similarly, flagellate and bacterial aggregate numbers increased slowly, but stayed on comparable low mean levels of 280 flagellates mL−1 and 78 aggregates mL−1 on day 21 of the experiment (Figure 4). In contrast, both MC treatments showed higher cell numbers as compared to the CON treatment. Between 0.8 and 0.5×106 bacterial single cells mL−1 were found in both replicates of the LMA treatment at the end of the experiment. Comparable numbers of bacterial single cell numbers were determined also in the replicate 1 of the DMA treatment (0.4×106 mL−1). The bacterial single cell numbers in the corresponding second replicate of the DMA treatment were about ten times higher (3.9×106 mL−1). Flagellate numbers in the filtrates of the LMA treatment were comparable high at the end of the experiment (mean value 0.67×104 mL−1), as well as bacterial aggregates (mean value 0.8×103 mL−1). Comparable numbers of flagellates were found in the filtrate of the first replicate of the DMA treatment (0.54×104 mL−1) as well as the highest amount of aggregates (4.0×103 mL−1) at the end of the experiment. However, rather low numbers of flagellates and aggregates were found in the second replicate of the DMA treatment, 0.15×104 mL−1 and 0.1×103 mL−1, respectively (Figure 4).

Bottom Line: Presence of live or destroyed cyanobacterial cells in the feed water decreased the permeate flux in the Microcystis treatments considerably.At the same time, the microbial biofilms on the filter membranes could successfully reduce the amount of microcystins in the filtrate below the critical threshold concentration of 1 µg L(-1) MC for human consumption in three out of four replicates after 15 days.We found pronounced differences in the composition of bacterial communities of the biofilms on the filter membranes.

View Article: PubMed Central - PubMed

Affiliation: Limnological Station, Institute of Plant Biology, University of Zurich, Kilchberg, Switzerland.

ABSTRACT
Gravity-driven membrane (GDM) ultrafiltration systems require little maintenance: they operate without electricity at ultra-low pressure in dead-end mode and without control of the biofilm formation. These systems are already in use for water purification in some regions of the world where adequate treatment and distribution of drinking water is not readily available. However, many water bodies worldwide exhibit harmful blooms of cyanobacteria that severely lower the water quality due to the production of toxic microcystins (MCs). We studied the performance of a GDM system during an artificial Microcystis aeruginosa bloom in lake water and its simulated collapse (i.e., the massive release of microcystins) over a period of 21 days. Presence of live or destroyed cyanobacterial cells in the feed water decreased the permeate flux in the Microcystis treatments considerably. At the same time, the microbial biofilms on the filter membranes could successfully reduce the amount of microcystins in the filtrate below the critical threshold concentration of 1 µg L(-1) MC for human consumption in three out of four replicates after 15 days. We found pronounced differences in the composition of bacterial communities of the biofilms on the filter membranes. Bacterial genera that could be related to microcystin degradation substantially enriched in the biofilms amended with microcystin-containing cyanobacteria. In addition to bacteria previously characterized as microcystin degraders, members of other bacterial clades potentially involved in MC degradation could be identified.

Show MeSH
Related in: MedlinePlus