Calculation of microbial growth efficiency from15N immobilization

1988 ◽  
Vol 6 (3) ◽  
pp. 239-243 ◽  
Author(s):  
D. S. Schimel
Keyword(s):  
Microbial Growth ◽  
Growth Efficiency ◽  
Microbial Growth Efficiency

scholarly journals Digestion in defaunated and refaunated sheep fed soybean oil hydrolysate or crushed toasted soybeans

1993 ◽  
Vol 41 (3) ◽  
pp. 205-219
Author(s):  
C.J. Van Nevel ◽  
S. De Smet ◽  
D.I. Demeyer
Keyword(s):  
Total Lipid ◽  
Microbial Growth ◽  
Intestinal Tract ◽  
Growth Efficiency ◽  
Minor Effect ◽  
Molar Percentage ◽  
Rumen Metabolism ◽  
Fermentation Pattern ◽  
A Minor ◽  
Microbial Growth Efficiency

Defaunated then refaunated sheep were given diets containing soyabean oil hydrolysate (SOH: 70 g/day) or an equivalent amount of lipids administered as crushed toasted soyabeans (TSB). Defaunation increased molar percentage of propionate in the rumen, while butyrate decreased. SOH caused a similar effect in both the defaunated and refaunated rumen, while the effect on acetate proportions was variable. Protozoal counts were lower after feeding SOH. Crushed toasted soyabeans had a minor effect on rumen fermentation pattern. Rumen digestibility of organic matter was decreased by both defaunation and SOH feeding, with a concomitant shift in digestion to the lower intestinal tract. Total tract digestibility was not affected. Both treatments increased nonammonia N flows at the duodenum, but this was only significant with defaunation. Total tract digestion of N remained almost constant. Defaunation resulted in more microbial protein reaching the duodenum. Except for the TSB diet, total lipid leaving the rumen equalled intake. Total tract digestibility of total lipid was much higher with SOH and TSB than with controls. Defaunation almost doubled microbial growth efficiency and this value tended to increase by SOH feeding. The decrease of protozoal count or even elimination of protozoa after lipid feeding could not entirely explain the change in rumen metabolism, as additional changes in defaunated sheep were shown.

Gas balance method for testing of microbial growth efficiency after carbon substrate pulse

1986 ◽  
Vol 6 (2) ◽  
pp. 123-128 ◽  
Author(s):  
L. A. Baburin ◽  
I. E. Shvinka ◽  
M. P. Ruklisha ◽  
U. E. Viesturs
Keyword(s):  
Microbial Growth ◽  
Growth Efficiency ◽  
Balance Method ◽  
Carbon Substrate ◽  
Microbial Growth Efficiency ◽  
Gas Balance

scholarly journals Heavy and wet: The consequences of violating assumptions of measuring soil microbial growth efficiency using the 18O water method

Elem Sci Anth ◽  
2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Grace Pold ◽  
Luiz A. Domeignoz-Horta ◽  
Kristen M. DeAngelis
Keyword(s):  
Microbial Community ◽  
Microbial Communities ◽  
Microbial Growth ◽  
Microbial Community Composition ◽  
Soil Microbial Communities ◽  
Growth Efficiency ◽  
Experimental Conditions ◽  
Soil Microbial ◽  
Use Efficiency ◽  
Microbial Growth Efficiency

Soils store more carbon than the biosphere and atmosphere combined, and the efficiency to which soil microorganisms allocate carbon to growth rather than respiration is increasingly considered a proxy for the soil capacity to store carbon. This carbon use efficiency (CUE) is measured via different methods, and more recently, the 18O-H2O method has been embraced as a significant improvement for measuring CUE of soil microbial communities. Based on extrapolating 18O incorporation into DNA to new biomass, this measurement makes various implicit assumptions about the microbial community at hand. Here we conducted a literature review to evaluate how viable these assumptions are and then developed a mathematical model to test how violating them affects estimates of the growth component of CUE in soil. We applied this model to previously collected data from two kinds of soil microbial communities. By changing one parameter at a time, we confirmed our previous observation that CUE was reduced by fungal removal. Our results also show that depending on the microbial community composition, there can be substantial discrepancies between estimated and true microbial growth. Of the numerous implicit assumptions that might be violated, not accounting for the contribution of sources of oxygen other than extracellular water to DNA leads to a consistent underestimation of CUE. We present a framework that allows researchers to evaluate how their experimental conditions may influence their 18O-H2O-based CUE measurements and suggest the parameters that need further constraining to more accurately quantify growth and CUE.

scholarly journals Comparative Toxicities of Salts on Microbial Processes in Soil

2016 ◽  
Vol 82 (7) ◽  
pp. 2012-2020 ◽  
Author(s):  
Kristin M. Rath ◽  
Arpita Maheshwari ◽  
Per Bengtson ◽  
Johannes Rousk
Keyword(s):  
Ionic Strength ◽  
N Mineralization ◽  
Microbial Growth ◽  
Growth Efficiency ◽  
Soil Salinization ◽  
Microbial Processes ◽  
Leucine Incorporation ◽  
Acetate Incorporation ◽  
Microbial Decomposition ◽  
Acute Response

ABSTRACTSoil salinization is a growing threat to global agriculture and carbon sequestration, but to date it remains unclear how microbial processes will respond. We studied the acute response to salt exposure of a range of anabolic and catabolic microbial processes, including bacterial (leucine incorporation) and fungal (acetate incorporation into ergosterol) growth rates, respiration, and gross N mineralization and nitrification rates. To distinguish effects of specific ions from those of overall ionic strength, we compared the addition of four salts frequently associated with soil salinization (NaCl, KCl, Na2SO4, and K2SO4) to a nonsaline soil. To compare the tolerance of different microbial processes to salt and to interrelate the toxicity of different salts, concentration-response relationships were established. Growth-based measurements revealed that fungi were more resistant to salt exposure than bacteria. Effects by salt on C and N mineralization were indistinguishable, and in contrast to previous studies, nitrification was not found to be more sensitive to salt exposure than other microbial processes. The ion-specific toxicity of certain salts could be observed only for respiration, which was less inhibited by salts containing SO42−than Cl−salts, in contrast to the microbial growth assessments. This suggested that the inhibition of microbial growth was explained solely by total ionic strength, while ion-specific toxicity also should be considered for effects on microbial decomposition. This difference resulted in an apparent reduction of microbial growth efficiency in response to exposure to SO42−salts but not to Cl−salts; no evidence was found to distinguish K+and Na+salts.

scholarly journals Substitution of Non-Protein Nitrogen for True Protein Increases Microbial Growth and Degradation of Fibrous Carbohydrates from Buffel Grass

2021 ◽  
Vol 25 (02) ◽  
pp. 492-500
Author(s):  
Jose Adelson Santana Neto
Keyword(s):  
Microbial Growth ◽  
Nitrogen Sources ◽  
Growth Efficiency ◽  
Protein Nitrogen ◽  
Rumen Microorganisms ◽  
Nitrogenous Compounds ◽  
Neutral Detergent Fibre ◽  
Buffel Grass ◽  
True Protein

The aim of this study was to evaluate the effects of different sources of nitrogenous compounds on the in vitro utilisation of neutral detergent fibre from buffel grass in advanced phenological stage, the experiment consisted of testing five levels of substitution of urea for casein: 0, 25, 50, 75 and 100%. The effects of the substitution levels were evaluated by in vitro incubation at different times: 0, 3, 6, 9, 12, 24, 36, 48, 72 and 96 h. The degradation rate of potentially degradable NDF increased up to the replacement level of 50%, but declined by 6.53 and 13.57% in the treatments with 75 and 100% substitution of urea for casein, respectively, as compared with the treatment without substitution. Discrete lag time was reduced by 1.31 h in the treatment with 50% substitution and by 2.7 h at 100% substitution, as compared with 0% substitution. The substitution of up to 50% non-protein nitrogen for true protein increased microbial growth efficiency by 16.1% as compared with the treatment without substitution. Acetate and propionate concentrations were not affected by the substitution of urea for casein. The use of 50% non-protein nitrogen and 50% true protein as nitrogen sources for rumen microorganisms favour microbial growth and optimise the degradation of neutral detergent fibre from low-protein buffel grass. © 2021 Friends Science Publishers

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