SOLID-STATE CP/MAS C-13 NMR ANALYSIS OF BACTERIAL AND FUNGAL CULTURES ISOLATED FROM A SOIL INCUBATED WITH GLUCOSE

Bacteria and fungi were isolated from a sample of the Meadows fine sandy loam, an Alfisol, and selectively cultured in nutrient solutions at 20°C for 5 days. The bacteria and fungiwere collected, washed with deionized water, freeze dried and analysed using conventionaland dipolar dephased solid state CP/MAS 13C n.m.r. spectroscopy. To obtain a quantitativeestimate of the chemical composition of the bacterial and fungal carbon, a recycle delayof 3-0 s was required to allow complete relaxation between pulses, and the acquired signalintensities had to be corrected for the amount of signal relaxation which occurred during thecontact time (i.e. TipH effects). The bacterial materials contained more alkyl and carboxylcarbon but less O-alkyl and acetal carbon than the fungal materials. Comparison of thecomposition of the bacterial and fungal carbon with that of the native and residual substratecarbon contained in the clay and light fraction of a sample of Meadows fine sandy loamincubated with 13C-glucose indicated that the soil microbial population was dominated byfungi. © 1990, CSIRO. All rights reserved.