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Research article1998Peer reviewed

Kinetics of Substrate-Induced Respiration (SIR): Theory

Stenström, John; Stenberg, Bo; Johansson, Mats

Abstract

respiration rate dp/dt after substrate addition in the SIR method represents the sum of the respiration rates of growing (re(mu t)) and nongrowing microorganisms (K). According to the equation SIR = r + K at the time of substrate addition, where r is the initial respiration rate of growing microorganisms. The equation is applied to examine the effects of soil moisture content and the antibiotic cycloheximide on SIR and its components. The SIR, K and mu increased with increasing soil moisture content while r decreased. The SIR was unaffected while K increased as much as r decreased, i.e. a shift from a growing to a nongrowing state occurred at the concentration of cycloheximide used and at two moisture levels. It is proposed that the qualitative division of the soil microflora into autochthonous and zymogenous populations is quantified by the equation. The equation can be used in terrestrial test systems of natural and anthropogenic effects and mechanisms on the microorganisms. It gives information on treatment effects on existing enzymes (r and K) and on enzyme synthesis as reflected in growth (mu). It will also be possible to form new ecophysiological constants in addition to the ones used today for assessing effects on the soil microflora and functional roles of its different parts.

Published in

AMBIO: A Journal of the Human Environment
1998, Volume: 27, number: 1, pages: 35-39
Publisher: ROYAL SWEDISH ACAD SCIENCES