I am trying to isolate the VOC volatile organic components by trichoderma fermentation. I have observed that most of the VOC are produced when the trichoderma grows in the forms of pellets (suspended form). According to model suggested by Pirt, in pellet phase oxygen is more likely to be limiting growth nutrient. The limitation starts when the pellet size is 0.077mm, which is very small. So my hypothesis is that compounds which I am getting is may be due to the oxygen limitation. But for me problem how to find out the limitation in case of fungal pellet. Do I need to grow the cells at very low aeration rate? Should I do it in batch phase or chemostat? Earlier I planned to use chemostat at dilution rate of 0.015/hr ( max. specific growth rate = 0.04/hr), but i faced feed contamination after 4-5 days. I want to know how to design an experiment so that I can get counterintuitive data? In pellet growth I did not even get consistent biomass reading? I want your valuable suggestions and feedback on these issues?
One way to reliably monitor and control dO2 levels is to use a dO2 measurement probe in your batch growth vessel or chemostat, for real-time dO2 monitoring. The aeration rate can be adjusted based on the measured dO2 level, either by periodic (e.g. daily or several times per day) manual adjustments of aeration flow rate, or more smoothly and semi-continuously by using an automatic feedback control loop--i.e. the dO2 probe readout is fed into an electronic controller; output from that controller is connected to a circuit that controls the aeration flow rate. Most controllers would also enable automatic semi-continuous logging of both the measured dO2 levels and the aeration flow rate (or aeration 'on' and 'off' times if using on/off aeration).
Of course, contamination by other oxygen-using micro-organisms would distort your aeration flow rate data.
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