Prokaryotic Diversity of the Composting Thermophilic Phase: The Case of Ground Coffee Compost

Investigating the sources and fate of per- and polyfluoroalkyl substances (PFAS) in food waste compost

Composting municipal food waste is a key strategy for beneficially reusing methane-producing waste that would otherwise occupy landfill space. However, land-applied compost can cycle per- and polyfluoroalkyl substances (PFAS) back into the food supply and the environment. We partnered with a pilot-scale windrow composting facility to investigate the sources and fate of 40 PFAS in food waste compost. A comparison of feedstock materials yielded concentrations of ∑PFAS under 1 ng g-1 in mulch and food waste and at 1380 ng g-1 in leachate from used compostable food contact materials. Concentrations of targeted ∑PFAS increased with compost maturity along the windrow (1.85-23.1 ng g-1) and in mature stockpiles of increasing curing age (12.6-84.3 ng g-1). Among 15 PFAS quantified in compost, short-chain perfluorocarboxylic acids (PFCAs) - C5 and C6 PFCAs in particular - led the increasing trend, suggesting biotransformation of precursor PFAS into these terminal PFAS through aerobic decomposition. Several precursor PFAS were also measured, including fluorotelomer carboxylic acids (FTCAs) and polyfluorinated phosphate diesters (PAPs). However, since most targeted analytical methods and proposed regulations prioritize terminal PFAS, testing fully matured compost would provide the most relevant snapshot of PFAS that could be land applied. In addition, removing co-disposed food contact materials from the FW feedstock onsite yielded only a 37 % reduction of PFAS loads in subsequent compost, likely due to PFAS leaching during co-disposal. Source-separation of food contact materials is currently the best management practice for meaningful reduction of PFAS in food waste composts intended for land application.

A concerted enzymatic de-structuring of lignocellulosic materials using a compost-derived microbial consortia favoring the consolidated pretreatment and bio-saccharification

The robustness of microbial consortia isolated from compost habitat encompasses the complementary metabolism that aids in consolidated bioprocessing (CBP) of lignocellulosic biomass (LCB) by division of labor across the symbionts. Composting of organic waste is deemed to be an efficient way of carbon recycling, where the syntrophic microbial population exerts a concerted action of lignin and polysaccharide (hemicellulose and cellulose) component of plant biomass. The potential of this interrelated microorganism could be enhanced through adaptive laboratory evolution (ALE) with LCB for its desired functional capabilities. Therefore, in this study, microbial symbionts derived from organic compost was enriched on saw dust (SD) (woody biomass), aloe vera leaf rind (AVLR) (agro-industrial waste) and commercial filter paper (FP) (pure cellulose) through ALE under different conditions. Later, the efficacy of enriched consortium (EC) on consolidated pretreatment and bio-saccharification was determined based on substrate degradation, endo-enzymes profiling and fermentable sugar yield. Among the treatment sets, AVLR biomass treated with EC-5 has resulted in the higher degradation rate of lignin (47.01 ± 0.66%, w/w) and polysaccharides (45.87 ± 1.82%, w/w) with a total sugar yield of about 60.01 ± 4.24 mg/g. In addition, the extent of structural disintegration of substrate after EC-treatment was clearly deciphered by FTIR and XRD analysis. And the factors of Pearson correlation matrix reinforces the potency of EC-5 by exhibiting a strong positive correlation between AVLR degradation and the sugar release. Thus, a consortium based CBP could promote the feasibility of establishing a sustainable second generation biorefinery framework.

Composting of post-consumption food waste enhanced by bioaugmentation with microbial consortium

There is escalating interest in composting of post-consumption food waste (PCFW) to recycle nutrients and mitigate pollution by inappropriate disposal. The present study aimed to evaluate the performance of bioaugmentation to composting of PCFW, which is in difficulties caused by high sugar, protein and gross lipid content. Inoculation of the microbial consortium effectively induced rapid temperature and pH rising, which led to OM reduction rate at 25.11 % and maturity at 150 % in terms of Germination Index value. EEMs-FRI showed that humification was accelerated in the thermophilic stage and further improved in the mature stage. Bacterial community analysis revealed that microbial inoculant ameliorated acidification, and expedited temperature and pH rising in the initial stage, which in turn accelerated bacteria community succession. The abundance of Actinobacteria was much higher in the thermophilic and mature stage in T2 treatment than in T1, which might explain rapid organic degradation. High temperature enriched thermophilic genera (Thermobifida, Compostibacillus, Neobacillus), and Pseudonocardia and Actinoplanes were enriched in the mature stage, which correlated to effective degradation of organic matter, humification and maturity. Temperature and pH mainly motivated bacterial succession. The results suggest that bioaugmentation is a favorable approach for efficient composting of PCFW.

Exploring the humification process of municipal sludge in hyperthermophilic composting through metagenomic and untargeted metabolomic

Hyperthermophilic composting (HC) has been widely recognized for the advantage of high treatment efficiency for organic wastes. However, the humification process is still unclear. In this study, the humification process of HC was investigated, compared to conventional composting (CK). The results showed that the highest composting temperature, organic matter degradation rate, and humification index in HC were 92.62 °C, 23.98%, and 1.59, while those in CK were 70.23 °C, 14.49 %, and 1.04, indicating HC accelerated humification process. Moreover, the results of metagenomic and untargeted metabolomic showed that the genes and metabolisms related to carbohydrate, lipid, amino acid, fatty acid, and nucleotide were more abundant in HC. Consequently, the metabolic pathways regarding organic matter degradation and microbial reproduction were enhanced in the high temperature stage of HC, further accelerating the humification reaction in the low temperature stage. This work contributes to the comprehension of the humification mechanism in HC.

Production of compost from logging residues

The implementation of forest management generates logging residue which can be used in several ways. One of the option is to use of logging residue in the composting process. Therefore, this study determined the possibility of producing compost based on logging residue and the produced fertilizer used to fertilize forest nurseries. Pine chips and sewage sludge were used for carrying out the study. The compost, as well as the leachate produced during composting, were characterized by high NPK content. The leachate collected at the end of the experiment was characterized by nitrogen content of approximately 6500 mg‧dm^-3, phosphorus of approximately 450 mg‧dm^-3, and potassium of approximately 500-700 mg‧dm^-3. In contrast, the compost produced contained approximately 0.57 g‧kg^-1 nitrogen, approximately 0.39 g‧kg^-1 phosphorus, and approximately 0.24 g‧kg^-1 potassium. The disadvantage in terms of the usefulness of the resulting fertilizer in forest nurseries is its pH, which exceeded 9.0.

Exogenous microbial antagonism affects the bioaugmentation of humus formation under different inoculation using Trichoderma reesei and Phanerochaete chrysosporium

This study was aimed at exploring the effect of antagonism of Trichoderma reesei (T.r) and Phanerochaete chrysosporium (P.c) on humification during fermentation of rice (RS) and canola straw (CS). Results showed that exogeneous fungi accelerated straw degradation and enzyme activities of CMCase, xylanase and LiP. P.c inhibited the activity of LiP when co-existing with T.r beginning, it promoted the degradation of lignin and further increased the production of humus-like substances (HLS) and humic-like acid (HLA) in later fermentation when nutrients were insufficient. The HLS of RTP was 54.9 g/kg RS, higher than the other treatments, and displayed more complex structure and higher thermostability. Brucella and Bacillus were the main HLA bacterial producers. P.c was the HLA fungal producer, while T.r assisted FLA and polyphenol transformation. Therefore, RTP was recommended to advance technologies converting crop straw into humus resources.

An inclusive outlook on the fate and persistence of pesticides in the environment and integrated eco-technologies for their degradation

Intensive and inefficient exploitation of pesticides through modernized agricultural practices has caused severe pesticide contamination problems to the environment and become a crucial problem over a few decades. Due to their highly toxic and persistent properties, they affect and get accumulated in non-target organisms, including microbes, algae, invertebrates, plants as well as humans, and cause severe issues. Considering pesticide problems as a significant issue, researchers have investigated several approaches to rectify the pesticide contamination problems. Several analyses have provided an extensive discussion on pesticide degradation but using specific technology for specific pesticides. However, in the middle of this time, cleaner techniques are essential for reducing pesticide contamination problems safely and environmentally friendly. As per the research findings, no single research finding provides concrete discussion on cleaner tactics for the remediation of contaminated sites. Therefore, in this review paper, we have critically discussed cleaner options for dealing with pesticide contamination problems as well as their advantages and disadvantages have also been reviewed. As evident from the literature, microbial remediation, phytoremediation, composting, and photocatalytic degradation methods are efficient and sustainable and can be used for treatment at a large scale in engineered systems and in situ. However, more study on the bio-integrated system is required which may be more effective than existing technologies.

Metagenomic analysis reveals the microbial degradation mechanism during kitchen waste biodrying

Biodrying is a treatment to remove moisture using bio-heat generated during organic degradation. Organic matter degradation and microbial metabolism were studied during the whole kitchen waste biodrying, using metagenomic analysis. After the 25-day biodrying process, carbohydrate, protein and lipid contents decreased by 83.7%, 27.8% and 79.3%, respectively, and their degradation efficiencies increased after the thermophilic phase. Lipase activity exceeded 10 mmol d^-1 g^-1 throughout biodrying. Cellulase and lipase activities recovered by 2.21% and 5.77%, respectively, after the thermophilic phase, while the protease activity had a maximum increment of 347%. Metabolic analysis revealed that carbohydrate, amino acid and lipid metabolism was possibly inhibited by the high temperature, but the relative abundances of related predicted functions recovered by more than 0.9%, 7% and 11%, respectively, by the end of biodrying. Protein function prediction suggests that β-oxidation, fatty acid biosynthesis, and the degradation of cellulose and chitin were possibly enhanced during the thermophilic phase. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that leucine, isoleucine and lysine could ultimately degraded to acetyl-CoA. Weissella, Aeribacillus and Bacillus were the genera with the most enriched functional genes during the whole biodrying process. These findings help elucidate the microbial degradation processes during biodrying, which provides further scientific support for improving the application of biodrying products.

Genome Sequence of the Thermophilic Soil Bacterium Ureibacillus terrenus ATCC BAA-384T

Ureibacillus terrenus TH9A^T (=ATCC BAA-384^T) was isolated from uncultivated soil in Italy in 1995. We present a draft genome sequence for the type strain, with a predicted genome length of 2,936,851 bp, containing 2,766 protein-coding genes, 82 RNA genes, and 5 CRISPR arrays, with a G+C content of 42.5%.