Microbiological aspects of biowaste during composting in a monitored compost bin

Abstract

Aims: To determine the microbial succession of the dominating taxa and functional groups of microorganisms and the total microbial activity during the composting of biowaste in a monitored process. Methods and Results: Biowaste (vegetable, fruit and garden waste) was composted in a monitored composting bin system. During the process, taxonomic and functional subpopulations of microorganisms were enumerated, and dominating colonies were isolated and identified. All counts decreased during the thermophilic phase of the composting, but increased again when the temperature declined. Total microbial activity, measured with an enzyme activity assay, decreased during the thermophilic phase, increased substantially thereafter, and decreased again during maturation. Bacteria dominated during the thermophilic phase while fungi, streptomycetes and yeasts were below the detection limit. Different bacterial populations were found in the thermophilic and mesophilic phases. In fresh wastes and during the peak-heating phase, all bacterial isolates were bacilli. During the cooling and maturation phase the bacterial diversity increased, including also other Gram-positive and Gram-negative bacteria. Among the fungi, Aspergillus spp. and Mucor spp. were predominant after the thermophilic phase. Conclusions: The microbial abundance, composition and activity changed substantially during composting and compost maturity was correlated with high microbial diversity and low activity. Significance and Impact of the Study: A more complete overview of the whole composting process of biowaste, based on microbial counts, species diversity and functional groups and abiotic parameters is presented, and the potential of a simple enzyme assay to measure total microbial activity was demonstrated.

Isolation and Impact of Cellulose-Degrading Bacteria on Physico-chemical and Microbiological Properties of Plant Residues during the Aerobic Decomposition

“…Their highest number was found in the raw material and the lowest one was after 60 days of the composting process. The same trend was recorded by other investigators confirming this decline could be attributed to the fact that during the curing phase the cellulose may become inaccessible to the enzymatic attack because of low water content or association with protective substances such as lignin (Ryckeboer et al, 2003Gazi et al, 2007El-Akshar et al, 2012).…”

Genomic sequence of the pathogenic and allergenic filamentous fungus Aspergillus fumigatus

“…Its conidia production is prolific, and so human respiratory tract exposure is almost constant 4 . A. fumigatus is isolated from human habitats 5 and vegetable compost heaps 6,7 . In immunocompromised individuals, the incidence of invasive infection can be as high as 50% and the mortality rate is often about 50% (ref.…”

Assessment of Microbial Communities and Their Relationship with Enzymatic Activity during Composting

“…Important enzymes involved in the composting process include dehydrogenase which reflects microbial activity, B-glucosidases which hydrolyze glucosides, urease involved in N-mineralization, and phosphatases that remove phosphate and sulfate groups from organic matter [3] [4]. Characterizing microbial communities along the process is important for achieving the effective management of a composting process and it may provide valuable information regarding process evolution and biodegradation rate [5] [6]. The investigation of the significant enzymes (e.g., dehydrogenases, β-glucosidases, phosphodiesterase and ureases) provides data for a correct estimation of the events that take place throughout the composting process [7].…”