Communities In Compost Research Articles

Isolation and identification of fungal communities in compost and vermicompost

This research illustrates the qualitative and quantitative composition of the mycoflora of both a green compost (thermophilically produced from plant debris) and a vermicompost (mesophilically produced by the action of earthworms on plant and animal wastes after thermophilic preconditioning). Fungi were isolated using three media (PDA, CMC, PDA plus cycloheximide), incubated at three temperatures (24, 37 and 45 C). Substantial quali-quantitative differences in the species composition of the two composts were observed. The total fungal load was up to 8.2 × 105 CFU/g dwt in compost and 4.0 × 105 CFU/g dwt in vermicompost. A total of 194 entities were isolated: 118 from green compost, 142 from vermicompost; 66 were common to both. Structural characterization of this kind is necessary to determine the most appropriate application of a compost and its hygienic quality.

Isolation and identification of fungal communities in compost and vermicompost

This research illustrates the qualitative and quantitative composition of the mycoflora of both a green compost (thermophilically produced from plant debris) and a vermicompost (mesophilically produced by the action of earthworms on plant and animal wastes after thermophilic preconditioning). Fungi were isolated using three media (PDA, CMC, PDA plus cycloheximide), incubated at three temperatures (24, 37 and 45 C). Substantial qualiquantitative differences in the species composition of the two composts were observed. The total fungal load was up to 8.2 X 10(5) CFU/g dwt in compost and 4.0 x 10(5) CFU/g dwt in vermicompost. A total of 194 entities were isolated: 118 from green compost, 142 from vermicompost; 66 were common to both. Structural characterization of this kind is necessary to determine the most appropriate application of a compost and its hygienic quality.

Increased Biotransformation Efficiency of Chunk-TNT-Contaminated Soil Using Acetone Pretreatments

Particulate, or chunk 2,4,6-trinitrotoluene (TNT), in soil was found to be recalcitrant to composting down to particle sizes of approximately 2 mm. Evidence for the colonization of TNT surfaces was obtained, but no pitting or otherwise preferential solid TNT solubilization was observed. Acetone pretreatments were used to make the chunk-TNT-contaminated soil more amenable to bioremediation. A pretreatment of acetone slurrying to dissolve and redisperse solid TNT in soil before applying remedial treatments was developed. The well-described treatment of composting was subsequently applied to native and acetone-pretreated contaminated soils. Acetone-pretreated soil responded to composting significantly better than untreated soil. After evaporating off the acetone used as pretreatment, composting microcosms held at 55°C showed sporadic removal from 3000 ppm to 300 ppm TNT in 24 days for untreated soil, while pretreated soil demonstrated conclusive removal from 3000 ppm to 18.1 ppm TNT in 6 days. Separate results indicated that residual acetone from pretreatment without subsequent evaporation was found to delay, but not otherwise inhibit, the compost's ability to degrade TNT. Community level physiological profile testing of 13-day-old composts, with pretreatment and residual acetone, suggests that three significantly different microbiological compost communities were equally adept at degrading the repartitioned TNT. The superior removal rates and efficiencies in the acetone-pretreated systems are likely to be due to the increased availability of TNT to the necessary microflora.

Purification and molecular analysis of microbian DNA from compost

A protocol was developed for the isolation of microbial DNA from compost. The isolated DNA was shown to be highly polymerized, pure enough for use with most molecular genetic techniques, and free of contaminating plant DNA. Two molecular genetic techniques used in comparisons of natural microbial communities were also optimized for comparisons of compost communities, and data obtained by the two techniques were compared in the analysis of the development of a microbial community in a single pilot scale reactor. The structures of the resident compost microbial community at different times were compared by Random Amplified Polymorphic DNA (RAPD) fingerprinting and by community DNA cross hybridization. RAPD analysis yielded characteristic fingerprints of the community at different times as the compost reactor shifted from thermophilic to mesophilic conditions. A limit of detection of unique species within the compost DNA was determined to be approximately 0.4% with this technique. A higher degree of resolution was observed between different samples using RAPD analysis than was observed with community cross hybridiization. Significant asymmetries in reciprocal hybridizations were observed with community cross hybridizations between samples, possibly resulting from differences between samples in both complexity and base composition (%GC) of the DNA.

Flow cytometric detection of viable bacteria in compost

Flow cytometry employing several vital stains was used to study the colonisation of sterile compost by Bacillus subtilis 168 (pAB224). The dyes used included rhodamine 123 (Rh123), carboxyfluorescein diacetate (CFDA) and chemchrome B. The results demonstrated the ability of flow cytometry to detect and enumerate viable bacteria in filtered compost extracts. Flow cytometry was also used to detect and study the viability of an indigenous compost community. Although it was possible to detect a viable bacterial population, the numbers of viable bacteria estimated were significantly different to those estimated from cfu.