Quantitative Assessment of Factors Affecting the Recovery of Indigenous and Released Thermophilic Bacteria from Compost

Abstract

Thermophilic actinomycetes and bacilli were recovered from mushroom compost by conventional dilution plating and sedimentation chamber-Andersen sampler methods. Excessive growth of thermophilic bacilli on dilution plates accounted for the poor recovery and limited diversity of actinomycete colonies, and this result was largely unaffected by the use of modffied extraction procedures and diluents. Assessment of the actinomycete population was more successfully achieved by applying the sedimentation chamber method, by using selective media, or both. Background resistance of the compost microflora to selective agents (kanamycin, novobiocin, tetracycline, thiostrepton, and NaCI) was extremely varied, but both actinomycetes and bacilli were particularly sensitive to tetracycline. The selective isolation of Thermoactinomyces spp. and Thermomonospora chromogena by novobiocin and kanamycin, respectively, was shown to be reproducible, and the use of high concentrations of kanamycin resulted in the isolation of a novel group of unidentified thermophilic actinomycetes. Comparison of nonselective nutrient media demonstrated that the nutrient-rich protoplast regeneration medium R5 was surprisingly efficient for actinomycete recovery. This medium was found to be particularly appropriate for the recovery of Saccharomonospora viridis BD125, introduced as spores into both sterile and fresh samples of mushroom compost. This stable pigmented variant of the S. viridis strains indigenous to compost was released at concentrations of up to 107 spores g of compost-' in order to provide information for future experiments on the release and recovery of genetically manipulated strains. The detection limits for this strain were in the region of 102 g-' from sterilized compost but only 105 g-1 from nonsterile compost. These figures correspond to mean recovery efficiencies of approximately 70% (sterilized compost) and 53% (fresh compost) of viable spores released. Further improvements in the detection and recovery of S. viridis strains released into compost should be achieved by the introduction of selectable markers developed from this information on the antibiotic resistance profile of the indigenous compost microflora.

Characters of aerated compost tea from immature compost that limit colonization of bean leaflets by Botrytis cinerea

“…The mean number of culturable bacteria or fungi in each ACT is also presented. Means within columns followed by the same letter were not significantly different at P = 0AE05: lsd is the least significant difference, and df is the residual degrees of freedom temperature for thermophilic fungi that moderate levels of nitrogen (Finstein and Morris 1975), (ii) a diverse range of bacteria that use numerous enzymes to degrade organic material and transfer soluble materials into bacterial cells (Ryckeboer et al 2003b), and (iii) a great diversity and abundance of actinobacteria (Fergus 1964;Finstein and Morris 1975;Amner et al 1988). These features indicate potential characters of compost, and hence compost teas, that might be associated with pathogen suppression.…”

Protease production by Streptomyces thermovulgaris grown on rapemeal‐derived media

“…Thermomonospora spp., Thermoactinomyces spp. and Faenia rectivzrgula were isolated from mushroom compost as described previously (Amner et al 1988;Yeoman and Edwards 1992) ; streptomycetes tested were S. thermovufgaris NCIB 10070, S. thermodenztr8cans NCIB 10078, S . fzvzdans NCIB 11416, S .…”

GROWTH RESPONSE AND RECOVERY IN SELECTIVE MEDIA OF A LYSINE AUXOTROPH ESCHERICHIA COLI FOR A RAPID MICROBIOLOGICAL ASSAY

“…Streptococcus and environmental Escherichia coli (Jeppesen 1995;Turgeon et al 1994;Kneifel et al 1994). Novobiocin interferes with DNA functioning by inhibiting DNA gyrase and has been used in a variety of selective media to inhibit Proteus, Enterobacren'aceue, microflora from several poultry environmental origins and thermophilic bacilli (Amner et al 1988;Tate er al. 1990;Moats 1978).…”