Microbiological Activity during Co-Composting of Food and Agricultural Waste for Soil Amendment

Abstract

This study aims to establish the relationship between ambient parameters and the diversity, composition, and function of microbial communities that predominate at each stage of the co-composting of food and agricultural waste. Culture-based and culture-independent methods were used to investigate the changes in the microbiota. The favorable conditions of high initial humidity and C/N ratio caused a decrease in the richness and biodiversity of the microbiota when such conditions existed. During the thermophilic stage, the total microbial number increased, and active mineralization of organic matter was carried out by members of the genera Bacillus, Caldibacillus, Aspergillus, and Penicillium. The fungal community was sensitive to drastic temperature changes. Byssochlamys dominated among fungi during the transition from the mesophilic to the thermophilic stage and during cooling. The biodiversity increased with time and was associated with the dynamics of germination and nitrification indices, so that the more diverse the microbial community, the higher the properties of compost that stimulate plant growth and development. The microbial community of the mature compost, together with mineral plant nutrients ready for consumption and humic compounds, make this compost a good soil additive.

Microbiota Dynamics of Mechanically Separated Organic Fraction of Municipal Solid Waste during Composting

“…The nitrification resulted in an increase in NO 3 − content on days 7-21. The most significant nitrification activity during the high-temperature stage was revealed in our earlier research [17].…”

“…In addition, during the experiment, with a total water content maintained at about 60%, some parts could have higher moisture due to the microzonality of the ms-OFMSW. In our early work, fresh food waste had a neutral pH value (6.9); then, in the first week of composting, the pH value decreased to 4.4 [17]. Therefore, the substrate acidification in the current work occurred before the composting started during the primary MSW processing due to the metabolism of the previously mentioned fungi and bacteria.…”

“…With a lack of nitrogen in the substrate, the rate of organic biodegradation decreases, and, conversely, an excess of nitrogen compounds leads to the emission of ammonia in a significant amount [39]. In addition, in our earlier work we were able to show that at high C/N, the biodiversity of the microbiota was lower than at lower values of C/N [17].…”

“…The values of pH, electrical conductivity (EC), water content, organic matter (OM), total organic carbon (C), NH 4 + and NO 3 − content, germination index (GI), total Kjeldahl nitrogen (N), and C/N were measured and calculated as described previously [17]. The water-soluble compounds, pH, EC, and GI were determined from a suspension of the sample (10 g) in 300 mL distilled water [18].…”

“…The composition of the microbial community was analyzed by the number of 16S rRNA genes and ITS copies. The processes of DNA isolation, PCR, and Illumina MiSeq high-throughput sequencing of the 16S rRNA gene region and ITS were performed by general techniques and were described in our earlier work [17]. For each sample, isolation of DNA was undertaken without replication; for each DNA sample, library preparation and sequencing were undertaken in duplicate.…”