Arapid and inexpensive method for biomass assay using relative electric potential difference

Microbial biomass assay is used in food, pharmaceutical, cosmetics and biotechnological industries in order to determine the rate of contamination, longevity and the possibility of use of the desired material in those industries. Measurement of physico-chemical properties and specterophotometric methods are used to monitor the culture medium variations induced by bacteria. These methods have substantial advantages over traditional plate counting and dilution techniques and significantly reduce the time needed to determine the microbial biomass amount.

Series of flasks containing microbiological media were added appropriate concentrations of chloramphenicol, ampicillin, vancomycin hydrochloride, ciprofloxacin hydrochloride, penicillin G procaiene, tetracyclin hydrochloride. The flasks were inoculated with Salmonella typhi Escherichia coli, Meticillin resistant Staphylococcus aureus, Pseudomonas aeruginosa Streptococcus pneumonia, Streptococcus pyogenes, respectively. The flasks were incubated at 37oC, 180 rpm. At intervals of 2h, total bacterial count, conductivity, resistivity, total dissolved solids, salinity, pH and electric potential difference (EPD) of culture broth were measured.

There is good correlation between EPD and OD. In the media containing no bacteria, EPD was constant. In the other media, an increase of EPD has been seen after 4-6h of incubation. Also, a sharp reduction of EPD has been seen in the middle of logarithmic phase.Discussion &

Correlation of biomass with cyclic voltametry had been reported in the literatures. However, there is no report on the correlation between EPD and bacterial growth. In this research, significant correlation has been seen between EPD and increase of bacterial biomass amount.