soper@maxzilla.encore.com (Pete Soper) (08/29/90)
Is there a rule of thumb for estimating the effect of temperature on the metabolic rate of simple organisms like yeast? That is, if I have the temperature and rate of CO2 production during the course of a fermentation, can I apply a correction to roughly predict what the flow would have been at (say) 3 degrees C higher or lower temperature? ----------------------------------------------------------------------- Pete Soper (soper@encore.com) +1 919 481 3730 Encore Computer Corp, 901 Kildaire Farm Rd, bldg D, Cary, NC 27511 USA
larry@kitty.UUCP (Larry Lippman) (08/30/90)
In article <12614@encore.Encore.COM>, soper@maxzilla.encore.com (Pete Soper) writes: > Is there a rule of thumb for estimating the effect of temperature > on the metabolic rate of simple organisms like yeast? That is, if > I have the temperature and rate of CO2 production during the course > of a fermentation, can I apply a correction to roughly predict what > the flow would have been at (say) 3 degrees C higher or lower > temperature? I don't believe there is any simple "rule of thumb" to give you any quantitative data in answer to your question, based upon the data you have available. To simplify this discussion, I will assume that "rate of growth" for a given microorganism is directly proportional to the amount of CO2 evolved for a given biomass. Let's also assume that we are dealing with mesophiles, although what I am stating is not much different for lower or higher temperature organisms. For any given microorganism there is a temperature at which maximum rate of growth occurs. Consider that a common yeast organism, such as Saccharomyces cerevisiae with a growth medium of molasses may have a temperature of say, 30 deg C at which maximum growth rate occurs. The rate of growth gets really non-predictable within only a few degrees C *above* this temperature. The rate of growth *below* this temperature is roughly logarithmic until we approach a minimum temperature at which growth can no longer occur. Depending upon the particular microorganism, this logarithmic region may extend below the temperature for maximum growth for perhaps 10 to 20 deg C, below which we again get unpredictable. While I have stated that over a limited region the rate of growth (and hence CO2 evolution) is roughly logarithmic, I would not at all be comfortable making any predictions merely based upon knowing CO2 flow rate at a given temperature. There are other factors to be considered, including but not limited to: (1) specific growth rate (u); (2) culture density; and (3) yield (i.e., grams per gram of substrate). For a given biomass and for a given reactor, growth versus temperature curves would be rather empirical. I have seen such data in my travels, and some curves look really *ugly* - i.e., nothing which anyone could readily predict without actual measurement. Larry Lippman @ Recognition Research Corp. "Have you hugged your cat today?" VOICE: 716/688-1231 {boulder, rutgers, watmath}!ub!kitty!larry FAX: 716/741-9635 {utzoo, uunet}!/ \aerion!larry