Certain types of bacteria may help in waste water cleanup, according to a Department of Science and Technology funded study.

The team headed by Prof. Arlene Llamado of the University of the Philippines Los Baños isolated five bacteria cultures from soils of an abandoned mine site in Mogpog, Marinduque to determine if these can form biofilms. Then the team assessed the bacteria’s potential in wastewater treatment applications.

Biofilms are the slimy substances secreted by certain types of bacteria, just like the slime on un-brushed teeth or the film on top of left-over soup. In hospital settings, biofilm-forming bacteria are notorious in spreading hospital-acquired infections because they are resistant to antibiotics and cleaning agents.

However, the researchers wanted to take advantage of the ability of microorganisms to form biofilms because they are negatively charged therefore they can attach to positively charged metal ions.
“By the simple idea of negatively charged polymers attaching to positively charged ions, we actually have a potential to remove heavy metal ions from waste water,” explained Prof. Lllamado.

She further explained that they collected samples from a mined out site where there is low concentration of organic elements and high concentration of copper, because they expected that bacteria living in these soils would have resistance to heavy metals.

All of the bacteria samples isolated from the site exhibited ability to produce biofilms. Further evaluation showed that all of these isolates were capable of removing heavy metals in water-copper solution. The planktonic cells of each bacterial isolate ate up the copper within six hours of contact time.

Since actual wastewaters may contain multiple metals, the team also tested the isolates in mixed metal solution containing copper, cadmium, lead, and zinc. Results revealed that three out of the five isolates decreased their efficiency in removing copper when exposed to mixed metal solution. Interestingly, one of the isolates called NV17 has shown dramatic increase in its ability to remove copper in multi-metal solution. However, Professor Llamado said that the reason for this occurrence was not yet tackled in the study.

Subsequent analysis of the bacteria revealed that the isolates NV112 an NV1A are species of Rhodococcus; NV17 and R11 are species of Bacillus, and NV2A is Pseudomonas sp.

Prof. Llamado revealed that further study is underway to test the ability of these bacterial isolates in removing metals in actual wastewater.

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