Physicochemical Changes and Microbiome Associations during Vermicomposting of Winery Waste

Abstract

Annually, the wine industry produces high amounts of waste that can be toxic if disposed of without pretreatment. Vermicomposting is an efficient and low-cost method of decomposing organic matter using earthworms under controlled conditions. The organic substrate used in the vermicomposting process affects microbial populations and reflects the dynamics of enzymatic activity, decomposition of organic matter, and nitrogen transformations. However, the microbiome associations during the whole process are still unexplored. Thus, the aim of the present study was to investigate physicochemical, enzymatic, microbial, and microbiome activities during vermicomposting of winery waste. In this vein, a rectangular vermireactor with Eisenia andrei and Eisenia fetida earthworms, loaded with winery waste, was used. At the end of the process, the carbon/nitrogen (C/N) ratio was decreased, the total nitrogen was increased, the pH was neutralized and excess enzymatic activities were recorded. The bacterial and fungal phyla detected by next-generation sequencing analysis identified Armatimonadetes, Bacteriodetes, Candidatus saccharibacteria, Chloroflexi, Cyanobacteria, Planctomycetes, and Proteobacteria and Ascomycota, Basidiomycota, Chytridiomycota, Entomophthoromycota, Glomeromycota, and Mucoromycota, respectively. Physicochemical and microbial changes occurring during vermicomposting of winery waste, along with the microbiome diversity at the beginning and end of the process, may lead to a better understanding of winery-waste biotransformation into effective biofertilizer.

Comparative Study of Vermicomposting: Apple Pomace Alone and in Combination with Wheat Straw and Manure

“…The content of Ca varied in the range from 3.89% ± 0.02 (E4) to 5.38% ± 0.03 (E1). The obtained Ca values in this study were higher than those reported by [66] (less than 2.5%) or Karapantzou et al [67] (less than 1.86%), possibly as a result of the Ca levels in the initial substrates or the duration of the composting process. The content of K increased during vermicomposting, reaching values at the end of the process of 0.69% ± 0.47−0.97%± 0.02.…”

“…The number of sulfate-reducing clostridia (except in treatments E1 and E2 at the beginning of the experiment) was below 10 2 CFU/g in all the treatments (Table 4). The reduction and elimination of these bacteria, as described by other researchers [67], are partly the result of the indirect activities of the earthworms. In other words, changes in the physical conditions of the substrate during the vermicomposting process, through the continuous aeration facilitated by earthworms, directly impact these anaerobic bacteria [28].…”

“…The observed dynamics of reduction may result from competition among the present microorganisms due to limited nutrient availability, the influence of environmental factors [67,84], and the complex relationship with the present earthworms [61]. Nevertheless, the sustained count of these bacteria on the 240th day of vermicomposting suggests the potential continuation of microbial processes in transforming the used substrates.…”

“…According to Parthasarathi and Ranganathan [70], microbial communities present in the gut of earthworms secrete enzymes, such as phosphatases, glycosidases, proteases, and ureases which are responsible for enhanced N, P, and K contents in vermicomposts. Very frequently, the newly formed organic matter also includes the decomposed tissues of the earthworms [67,71]. According to the literature data, both increases and decreases in element concentrations have been observed in vermicomposting products depending on the types of waste used for vermicomposting [72].…”

Nature‐based strategies to regenerate the functioning and biodiversity of vineyards

“…Vermicomposting (organic matter transformation by earthworms) is another viable biotechnology for the treatment of wine organic wastes, as demonstrated by several studies (Gómez-Brandón et al, 2021Karapantzou et al, 2023;Paradelo et al, 2011). Thus, the potential valorisation of by-products generated during wine production enables the recycling of organic matter and nutrients, fostering sustainable viticulture within a circular economy framework.…”