An improved method for measuring soil microbial activity by gas phase flow injection analysis

Abstract

the rate of carbon dioxide production is commonly used as a measure of microbial activity in the soil. the traditional method of co 2 determination involves trapping co 2 in an alkali solution and then determining co 2 concentration indirectly by titration of the remaining alkali in the solution. this method is still commonly employed in laboratories throughout the world due to its relative simplicity and the fact that it does not require expensive, specific equipment. however, there are several drawbacks: the method is timeconsuming, requires large amounts of chemicals and the consistency of results depends on the operator's skills. with this in mind, an improved method was developed to analyze co 2 captured in alkali traps, which is cheap and relatively simple, with a substantially shorter sample handling time and reproducibility equivalent to the traditional titration method. A comparison of the concentration values determined by gas phase flow injection analysis (gpfIA) and titration showed no significant difference (p > 0.05), but gpfIA has the advantage that only a tenth of the sample volume of the titration method is required. the gpfIA system does not require the purchase of new, costly equipment but the device was constructed from items commonly found in laboratories, with suggestions for alternative configurations for other detection units. furthermore, gpfIA for co 2 analysis can be equally applied to samples obtained from either the headspace of microcosms or from a sampling chamber that allows co 2 to be released from alkali trapping solutions. the optimised gpfIA method was applied to analyse co 2 released from degrading hydrocarbons from a site contaminated by diesel spillage.Index terms: co 2 , microbial respiration, titration, infrared, fIA.(1) received for publication in february 17, 2011 and approved in november 30, 2011. (2)

Microbiocenosis characteristics of agrogenically altered acid brown forest soils in humid subtropics of Russia

“…Cellulose-decomposing microorganisms -at Hutchinson's medium, the percentage content of soil foul particles reflecting the development of free-living nitrogen fixers of the Azotobacterecea family, at Ashby's nitrogen-free medium, the total number of bacteria was determined by the photocolorimetric method in P.A. Kozhevin modification using fluorescein diacetate [13][14][15][16]. The potential activity determination of nitrogen fixation was carried out by the acetylene reduction method, CO2 emission from the soil -by the absorption method [17] with the titrimetric end.…”

Variable pressure pulsation frequency optimization in gas double-dynamic solid-state fermentation (GDSSF) based on heat balance model

“…Carbon dioxide evolution is commonly used as a measure of microbial activity [21]. Therefore, the metabolic heat is directly relevant to the carbon dioxide evolution.…”