Microbial Population Dynamics and Enzyme Activities During Composting

Abstract

The changes in population size of different microbial groups (total aerobic heterotrophs, actinomycetes, fungi, fecal coliforms, ammonium-and nitrite-oxidizing bacteria, and denitrifying bacteria) and the activities of 19 different enzymes (three phosphatases, threeesterases, two proteases, three amino-peptidases, and eight glycosyl-hydrolases) were examined during cocomposting of poultry litter (a mixture of poultry manure, waste feed, feathers, and wood shavings) and yard trimmings (a mixture of grass clippings, leaves, and wood barks). Three piles with forced aeration were established by mixing 2:1 (vIv) ratio of poultry litter and yard trimmings. During composting, samples were taken at three different locations (top, middle, and bottom) of the forced aeration piles for microbial and enzyme analyses. Results demonstrated that population size of different microbial groups was not a limiting factor in this composting process as the microorganisms in the poultry litter + yard trimmings compost are in great abundance. Although the numbers of these microbial groups were reduced by high temperature, their populations multiplied rapidly as composting progressed. Fecal coliforms were eliminated by day 49, suggesting that the poultry litter + yard trimmings compost showed an overall increase in diversity and relative abundance of extracellular enzyines present as composting progressed. The population of fungi and actinomycetes (microorganisms active in degradation of cellulose, hemicellulose, and lignin) were positively correlated with esterase, valine amino-peptidase, a-galactosidase, l3-glucosidase, and lipase. Of all 19 enzymes examined, :B-galactosidase (enzyme involved in the hydrolysis of lactose) had the most significant positive correlation with microbial populations, such as total aerobic heterotrophs, ammonicyn-and nitrite-oxidiiing bacteria, denitrifying bacteria, and fecal coliforms. Cystine amino peptidase, chymotrypsin, and trypsin showed no evidence of activity during the entire period of composting. This composting process repre-'seri.ted a combined activity of a wide succession of environments in the compost pile as one microbial group I enzyme overlapped the other and each emerged gradually as a result of the continual Ch3.J.lge in temperature as well as moisture content, °2 and CO2 level, and progressive breakdown of complex compounds to simpler ones..

Fate of non O157 Shiga toxigenic Escherichia coli in composted cattle manure

“…Although the elimination of pathogens by composting has been well documented (Deportes et al, 1998;Tiquia et al, 2002;Larney et al, 2003), composting times and temperatures required to achieve elimination or reduction of the number of E. coli vary widely. Turner (2002) demonstrated inactivation of E. coli in farmyard manure, pig feces, and cereal straw already after 2h at 55 o C. In contrast, Lau and Ingham (2001) reported that E. coli could be cultured from bovine manure kept for 19 weeks at 21 o C. In the present study, E. coli could be cultured at every condition tested after up to 120 days, however the non-O157 STEC-stx2-gene strains were not found after 30 days, indicating that competition among the bacteria associated with the temperature seem to be very important aspects.…”

Prediction of temperature and thermal inertia effect in the maturation stage and stockpiling of a large composting mass

“…There is abundant literature related to different aspects of composting, such as microbiological studies (Tiquia et al, 2002), changes of chemical composition (Pichler et al, 2000), technical and operational considerations (Wong and Fang, 2000) or even some aspects of process modeling such as kinetics (López-Zavala et al, 2004). However, there is scarce information about the prediction of temperature profiles in composting processes, especially at full-scale.…”

Resistance of Conifer Needle Polyolefin Composites (CNPCs) Against Biodecomposition Caused by Fungi

“…It was accompanied by the occurrence of the peak spectrum characteristic for cellulose (1317 cm −1 ). Biodegradation of lignocellulose (derived from the plant filler) of the composites results from collaboration of some fungi, actinomycetes and bacteria [48,[71][72][73]. The observed differences can be indicative for different proportions of cellulolytic and ligninolytic microorganisms which have the ability of decomposing resin acids in both substrates.…”