I am performing modelling of microbial fuel cell and for that, I want to find out the amount of mass of biofilm formed on the anode surface and the volume fraction of active biomass in a biofilm? So what are the techniques available by which I can find out the above things?
If you mean destructively, you can place the ‘device’ in an ultrasonic cleaning bath and remove the biofilm from the substratum. You can plate count the suspension of cells or filter for dry weight (bearing in mind the presence of extracellular polysaccharide). But you mention “active”. Tetrazoleum dye reduction is a ‘measure’ of electron transport activity. An alternative is to image the intact biofilm with the Live/Dead test kit - https://www.thermofisher.com/order/catalog/product/L7007#/L7007
Technique for accurate biomass estimation in biofilm is not yet properly developed in an easy quantitative format. Besides, there are several approaches and the best choice depends on what are your specific objectives. The simplest way is to remove the biofilm from the anode using sonication or just simple gloves finger rubbing in sterile water. Then shake well your suspension and measure OD at 600 nm. Finally, convert OD to dry masa using a preliminary found conversion factor for your bacteria. If cell mass is enough for direct dry weight - that would be the best. Before drying take aliquots of suspension for the phase-contrast, microscopy to characterize the heterogeneity of population: how many single and aggregated cells, morphological diversity, the normal and the 'ghosts' (empty dead cells). If you have a fluorescent microscope, buy the live/dead kit and determine the fraction of viable cells. From the dry mass, you can calculate the wet mass (roughly multiply by 10) and then the volume assuming the average density of wet cells 1.08 g/cc. Good luck!
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