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Saccharomyces cerevisiae (/ ˌ s ɛr ə ˈ v ɪ s i. iː /) (brewer's yeast or baker's yeast) is a species of yeast (single-celled fungal microorganisms). The species has been instrumental in winemaking, baking, and brewing since ancient times. It is believed to have been originally isolated from the skin of grapes.
It has been observed that the doubling time of this yeast is approximately 3 hours at 23 °C in yeast nitrogen base broth containing 20% (w/v) fructose (pH 4.0). In more stressful conditions, this generation time is significantly extended. [11]
Komagataella is a methylotrophic yeast within the order Saccharomycetales. It was found in the 1960s as Pichia pastoris , with its feature of using methanol as a source of carbon and energy. [ 2 ] In 1995, P. pastoris was reassigned into the sole representative of genus Komagataella , becoming Komagataella pastoris . [ 3 ]
This resulted in Synechococcus 7942 reducing its doubling time from 6.8 to 2.3 hours. [ 5 ] Also modified strains of S. elongatus have high prospects in production of 2,3-butanediol and other substances, which can be used in plastic and fuel production.
In comparison to batch culture, bacteria are maintained in exponential growth phase, and the growth rate of the bacteria is known. Related devices include turbidostats and auxostats. When Escherichia coli is growing very slowly with a doubling time of 16 hours in a chemostat most cells have a single chromosome. [1]
The notion of doubling time dates to interest on loans in Babylonian mathematics. Clay tablets from circa 2000 BCE include the exercise "Given an interest rate of 1/60 per month (no compounding), come the doubling time." This yields an annual interest rate of 12/60 = 20%, and hence a doubling time of 100% growth/20% growth per year = 5 years.
Most commonly apparent in species that reproduce quickly and asexually, like bacteria, exponential growth is intuitive from the fact that each organism can divide and produce two copies of itself. Each descendent bacterium can itself divide, again doubling the population size (as displayed in the above graph). [2]
Luria and Delbrück [5] estimated the mutation rate (mutations per bacterium per unit time) from the equation = [ ()] where β is the cellular growth rate, n 0 is the initial number of bacteria in each culture, t is the time, and