Life on Earth spans a range of temperatures and exhibits biological growth rates that are temperature dependent. While the observation that growth rates are temperature dependent is well known, we have recently shown that the statistical distribution of specific growth rates for life on Earth is a function of temperature (Corkrey et al., 2016). The maximum rates of growth of all life have a distinct limit, even when grown under optimal conditions, and which vary predictably with temperature. We term this distribution of growth rates the biokinetic spectrum for temperature (BKST). The BKST possibly arises from a trade-off between catalytic activity and stability of enzymes involved in a rate-limiting Master Reaction System (MRS) within the cell. We develop a method to extrapolate quantile curves for the BKST to obtain the posterior probability of the maximum rate of growth of any form of life on Earth. The maximum rate curve conforms to the observed data except below 0°C and above 100°C where the predicted value may be positively biased. The deviation below 0°C may arise from the bulk properties of water, while the degradation of biomolecules may be important above 100°C. The BKST has potential application in astrobiology by providing an estimate of the maximum possible growth rate attainable by terrestrial life and perhaps life elsewhere. We suggest that the area under the maximum growth rate curve and the peak rate may be useful characteristics in considerations of habitability. The BKST can serve as a diagnostic for unusual life, such as second biogenesis or non-terrestrial life. Since the MRS must have been heavily conserved the BKST may contain evolutionary relics. The BKST can serve as a signature summarizing the nature of life in environments beyond Earth, or to characterize species arising from a second biogenesis on Earth.

Item Type:	Refereed Article
Keywords:	Bayesian, biokinetic spectrum for temperature, habitability, limits of life, temperature-dependent growth, quantile regression
Research Division:	Physical Sciences
Research Group:	Astronomical sciences
Research Field:	Astrobiology
Objective Division:	Expanding Knowledge
Objective Group:	Expanding knowledge
Objective Field:	Expanding knowledge in the biological sciences
UTAS Author:	Corkrey, R (Dr Ross Corkrey)
UTAS Author:	McMeekin, TA (Professor Thomas McMeekin)
UTAS Author:	Bowman, JP (Associate Professor John Bowman)
UTAS Author:	Olley, J (Professor June Olley)
UTAS Author:	Ratkowsky, D (Dr David Ratkowsky)
UTAS Author:	Ross, T (Professor Tom Ross)
ID Code:	114108
Year Published:	2018
Web of Science® Times Cited:	5
Deposited By:	TIA - Research Institute
Deposited On:	2017-02-07
Last Modified:	2019-08-06
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