Microbial biomass estimation

Karl, D.M. and Dobbs, F.C. (1998) Molecular Approaches to Microbial Biomass Estimation in the Sea, in Molecular Approaches to the Study of the Ocean (ed. K.E. Cooksey), Chapman and Hall, London, pp. 29-81. 

Smith, J.L. and Paul, E.A. (1990) The significance of soil microbial biomass estimations. In Bollag, j.M. and Stotzky, G. (eds) Soil Biochemistry. Marcel Dekker, New York, pp. 357-395. 

ROSS D.J., TATE K.R., CAIRNS A. and PANSIER E.A. 1980. Microbial biomass estimations in soils from tussock grasslands by three biochemical procedures. Soil Biology and Biochemistry, 375-383. 

Combining ammonium immobilization rates with estimates of C inputs and C maintenance requirement (proportional to the active microbial biomass), whose difference gave C available for microbial growth from the same experimental system (111,128), it allowed the building up of a conceptual model for C and N... 

H. Van der Werf and W. Verstraete, Estimation of active soil microbial biomass by mathematical analysis of respiration curves development and verification of the model. Soil Biol. Biochem. 19 252 (1987). 

The Rothamsted Carbon Model (RothC) uses a five pool structure, decomposable plant material (DPM), resistant plant materials (RPM), microbial biomass, humified organic matter, and inert organic matter to assess carbon turnover (Coleman and Jenkinson 1996 Guo et al. 2007). The first four pools decompose by first-order kinetics. The decay rate constants are modified by temperature, soil moisture, and indirectly by clay content. RothC does not include a plant growth sub-module, and therefore NHC inputs must be known, estimated, or calculated by inverse modeling. Skjemstad et al. (2004) tested an approach for populating the different pools based on measured values. 

Microscopic counting is still the most direct method of estimating the amount of microbial biomass in soil but is technically difficult and completely unsuitable for routine use. Thin films are prepared from an agar-soil suspension, are mounted on microscope slides, and then are treated with an appropriate stain. Phenolic aniline blue is often used as it stains protein and is thus considered to give an estimate of the entire population. The numbers... 

Chloroform fumigation also increases the amount of total N extractable with 0.5 M K2S04. Brookes et al. (1985) showed that this extra N also comes from the microbial biomass and proposed that biomass N could be estimated from the relationship, Biomass N = 2.22 EN, where EN is analogous to Ec. 

The weight of soil used in the measurement depends on the initial soil microbial biomass concentration and the flask volume. Normally, 20-40 g moist soil is suitable for this measurement. Lin and Brookes (1999a) showed that SIR can give reliable estimates of microbial biomass in unamended soils, soils that contain actively decomposing plant residues, or soils recently treated with pesticides or fumigants. The final results are usually expressed as the SIR rate (tl C02 evolved g soil h Biomass carbon (Bc) is estimated by Bc (gig C g l soil) = 15 SIR (Lin and Brookes 1999a). 

Kaiser, E.-A., Mueller, T., Joergensen, R. G., Insam, H., and Heinemeyer, O. (1992). Evaluation of methods to estimate the soil microbial biomass and the relationship with soil texture and organic matter. Soil Biol. Biochem. 24, 675-683. 

Lin, Q. and Brookes, P. C. (1999b). Arginine ammonification as a method to estimate soil microbial biomass and microbial community structure. Soil Biol. Biochem. 31,1985-1997. 

Mancuso, C.A., Franzmann, P.D., Pourtan, H.A., and Nichols, P.D. (1990) Microbial community structure and biomass estimates of a methanogenic Antarctic lake ecosystem as determined by phospholipid analyses. Microb. Ecol. 19, 73-95. 

Table 17.1. Fungal and bacterial biomass associated with decomposing leaves in streams. All values are maximum biomass estimates from litter bag decomposition studies except the study by Findlay et al. (2002b) where average microbial biomass from randomly collected leaves was estimated...

FeigI, B. J., G. P. Sparling, D. J. Ross, and C.C. Ceni. 1995. Soil microbial biomass in Amazonian soils evaluation of methods and estimates of pool sizes. Soil Biology and Biochemistry 27 1467-1472. 

Yentumi and Johnson (6) reported that frequency of pesticide applications shifted the population, and repeated applications of paraquat lowered the size of the microbial biomass as determined by plate counts. Moorman (19) approached the estimation of pesticide degrader biomass size using an MPN procedure. He found that following high rate (60 /xg g ) applications of EPTC in soils enhanced for EPTC degradation, the enhanced biomass was increased as compared to the control soil. 

The substrate addition method for biomass estimation relies on the fact that the biomass response to the introduction of the pesticide is reflected in the response to the glucose. Fumigation relies on the conversion of the specifically labeled biomass to C-C02- From both estimations it is clear that the size of microbial biomass that can use the carbon in the carbofuran side-chain is small. Karns et al. (11) has shown that carbofuran may serve as nitrogen source for some organisms. Our estimates would overlook this N utilization. It is likely that organisms that utilize methylamine, the primary degradation product, for nitrogen would overlook this source of carbon. Data on bacterial use of methylamine is, however, limited. 

Holm-Hansen, O. and Pearl, H.W., 1972. The applicability of ATP determination for estimation of microbial biomass and metabolic activity. Mem. 1st. Ital. Idrobiol., 29 149—168. 

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