Lactic acid bacteria modulate organic acid production during early stages of food waste composting

Influence of biochar-based microbial agents on post-consumption food waste composting

Recycling nutrients by post-consumption food waste (PCFW) composting is impeded by the slow composting process because of the high perishability and moisture content of PCFW. Concerning this issue, a biochar-based microbial agent with trehalose as a protectant was developed, and was evaluated as inoculum in PCFW composting. Inoculation effectively ameliorated acidic conditions, accelerated organics degradation resulting in quick temperature rising, shortened maturation from 28 to 14 days, and altered the succession of the bacterial community structure. The combination of microbial consortium and biochar effectively inhibited the acid-producing bacteria Weissella and increased Bacillus, which contributed to a better condition for indigenous microbes by ameliorating the acidic condition of PCFW. This further expedited temperature rising that selectively enriched Firmicutes (Bacillus, Compostibacillus, Novibacillus) and Actinobacteria (Pseudonocardia) at the thermophilic stage. Moreover, carbon cycle was strengthened by chemoheterotrophy and aerobic chemoheterotrophy, while fermentation was inhibited, which was in favor of organic material degradation. The addition of 5% trehalose further enhanced the effect, and increased germination index to 152% at day 14. This study suggested that a biochar-based microbial agent was an efficient inoculant specifically for PCFW composting.

Food, Health, and Environmental Impact of Lactic Acid Bacteria: The Superbacteria for Posterity

Lactic acid bacteria (LAB) are Gram-positive cocci or rods that do not produce spores or respire. Their primary function is to ferment carbohydrates and produce lactic acid. The two primary forms of LAB that are currently recognized are homofermentative and heterofermentative. This review discusses the evolutionary diversity and the biochemical and biophysical conditions required by LAB for their metabolism. Next, it concentrates on the applications of these bacteria in gut health, cancer prevention, and overall well-being and food systems. There are numerous uses for LAB, including the food and dairy sectors, as probiotics to improve human and animal gut-health, as anti-carcinogenic agents, and in food safety as biopreservatives, pathogen inhibitors, and reducers of anti-nutrients in foods. The group included many genera, including Aerococcus, Carnobacterium, Enterococcus, Lactobacillus, Lactococcus, Leuconostoc, Streptococcus, Tetragenococcus, Vagococcus, and Weissella. Numerous species of Lactobacillus and Bifidobacterium genera as well as other microbes have been suggested as probiotic strains, or live microorganisms added to meals to improve health. LAB can colonize the intestine and take part in the host's physiological processes. This review briefly highlights the role of these bacteria in food safety and security as well as aspects of regulation and consumer acceptance. Finally, the recent innovations in LAB fermentations and the limitations and challenges of the applications of LAB in the food industry are discussed. Notwithstanding recent developments, the study of LAB and their functional components is still an emerging topic of study that has not yet realized its full potential.

Industrial-scale aerobic composting with the addition of Paenibacillus mucilaginosus: Improving product quality and removing antibiotic resistance genes

This study comprehensively investigated the effects of adding Paenibacillus mucilaginosus to industrial-scale compost on compost quality, microbial community dynamics, and antibiotic resistance genes (ARGs). The results of this investigation unequivocally demonstrated that the inclusion of Paenibacillus mucilaginosus prolonged the thermophilic phase of composting, thereby enhancing organic matter decomposition and facilitating nitrogen fraction conversion. Moreover, the inoculation of Paenibacillus mucilaginosus altered the microbial community structure during the rapid heating and thermophilic stages. Significantly, the removal rates of tetM, tetR, and sul1 were 99.84%, 99.68%, and 97.61%, respectively, with inoculation increasing these rates by 8.94%, 9.85%, and 9.34%, respectively, compared to the control (P < 0.05). These findings highlighted the efficacy of incorporating Paenibacillus mucilaginosus into industrial-scale compost as a potent strategy to enhance nutrient transformation processes and mitigate ARG activity.

Development of a Pre-Modification Strategy to Overcome Restriction-Modification Barriers and Enhance Genetic Engineering in Lactococcus lactis for Nisin Biosynthesis

Due to the barriers imposed by the restriction-modification (RM) system, Nisin-producing industrial strains of Lactococcus lactis often encounter low transformation efficiency, which seriously hinders the widespread application of genetic engineering in non-model L. lactis. Herein, we present a novel pre-modification strategy (PMS) coupled with optimized plasmid delivery systems designed to systematically evade RM barriers and substantially improve Nisin biosynthesis in L. lactis. Through the use of engineered Escherichia coli strains with methylation profiles specifically optimized for L. lactis C20, we have effectively evaded RM barriers, thereby facilitating the efficient introduction of large Nisin biosynthetic gene clusters into L. lactis. The PMS tools, which significantly improve the transformation efficiency (~103 transformants per microgram of DNA), have been further improved in combination with a Rolling Circle Amplification, resulting in a higher enhancement in transformation efficiency (~104 transformants per microgram of DNA). Using this strategy, large Nisin biosynthetic gene clusters and the expression regulation of all genes within the cluster were introduced and analyzed in L. lactis, leading to a highest Nisin titer of 11,052.9 IU/mL through a fed-batch fermentation in a 5 L bioreactor. This is the first systematic report on the expression regulation and application of a complete Nisin biosynthesis gene cluster in L. lactis. Taken together, our studies provide a versatile and efficient strategy for systematic evasion and enhancement of RM barriers and Nisin biosynthesis, thereby paving the way for genetic modification and metabolic engineering in L. lactis.

The inoculation of Bacillus paralicheniformis and Streptomyces thermoviolaceus enhances the lignocellulose degradation and microbial communities during spent mushroom substrate composting

The burgeoning global mushroom industry has precipitated challenges related to the efficient and sustainable utilization of spent mushroom substrate (SMS). Composting is regarded as an efficient way for the ecological utilization of SMS. The addition of microbial inoculants can promote the composting process and improve the quality of compost products. This study introduced two bacterial inoculants, Bacillus paralicheniformis HL-05 (BP) and Streptomyces thermoviolaceus LC-10 (ST), into the composting process of SMS. The impact of these inoculants was evaluated through analyses of physicochemical properties, lignocellulose degradation, and high-throughput sequencing to elucidate their ecological roles and optimize the composting process. The results suggest that inoculation with BP and ST significantly prolonged the thermophilic stage by 2-3 days, representing an increase of 22.22-33.33%. Moreover, it boosted the degradation rates of cellulose, hemicellulose, and lignin by 18.37-29.77%, 35.74-50.43%, and 40.32-40.83%, respectively, compared to the control. Furthermore, inoculation rapidly altered the microbial community structure during the rapid temperature-rising stage and strengthened interconnections among composting microorganisms. The microbial inoculation substantially enhanced the proliferation of thermophilic lignocellulose-degrading microorganisms during the thermophilic stage, thereby facilitating the utilization of lignocellulose. This study proposes a novel and effective strategy for SMS composting using microbial inoculants.

Unveiling the effect of PFOA presence on the composting process: Roles of oxidation stress, carbon metabolism, and humification process

Perfluorooctanoic acid (PFOA), an emerging pollutant, has been frequently detected in organic solid waste. It becomes a major concern for compost application, but studies on its toxic effects during composting are rare. This study evaluated the impact of PFOA presence at the environmentally relevant level on the humification process and microbiology during composting. The results showed that the PFOA presence (15.5 μg/kg dry) caused 45.5 % and 40.5 % decreases in the total organic carbon and humic acid-like substances, respectively. PFOA negatively affected microbial activity during the thermophilic period, as evidenced by the increases in reactive oxygen species and lactate dehydrogenase concentration. It altered the microbial community with an enrichment of Bacteroidota, conducive to resisting press. Unexpectedly, the PFOA presence induced hormesis at the maturity period, consistent with stimulated carbon metabolism (i.e., glycolysis and oxidative phosphorylation). The modulated microbial metabolism stimulated the catabolic metabolism of small-molecule humus precursors and reduced intracellular quinone availability. Furthermore, the secretion of auxiliary activities for crude fiber degradation was suppressed, which decreased the generation of extracellular quinone, and thereby impeded the humification process. These findings deciphered the metabolic response of composting to PFOA presence and highlighted the potential carbon loss of PFOA-containing composting.

Effect of thermophilic bacterial complex agents on synergistic humification of carbon and nitrogen during lignocellulose-rich kitchen waste composting

This work reported the effects of thermophilic bacterial agents on degrading persistent lignocellulose and reducing the loss of valuable nitrogen in kitchen waste (KW) composting. The results showed that thermophilic bacterial compound agents improved the high temperature period by 8 days, and increased the ligninase activity by 0.5-3 times during the composting process. The activity of cellulase increased up to 1 time in agent A (Geobacillus, Clostridium caenicola, Haloplasma) adding group by improving the microbial activity of lignocellulosic degradation metabolic pathways. Nitrogen storage increased to 70% in group added with agent B (Clostridium caenicola, Geobacillus, Clostridium sp. TG60-81) by increasing the population abundance of nitrogen-fixing microorganisms such as Bacillus, Hungateiclostridium and Herbaspirillum, and changed amino acid metabolic pathways. In general, agents A and B could increase the thermophilic phase, optimize the microbial community structure, realize the synergistic humification of carbon and nitrogen, and convert KW into mature and high quality fertilizers.

Agronomic potential of different fermented organic composts based on agro-industrial plant waste

Organic composts such as "bokashi", obtained from the fermentation of bran mixtures and inoculated with microorganisms, improve soil characteristics. In Brazil, the most widely used formulation for the production of this compost is obtained from a mixture of wheat and castor bean bran, but both have a high monetary cost. Replacing these components with regionally available sources represents the possibility of reducing costs and making more sustainable use of this waste. The aim of this study was to analyze the chemical characteristics and determine the availability of nitrogen for the plants. The study was divided into two stages, consisting of an incubation test in the laboratory and a bioassay in the greenhouse using forage sorghum as an indicator species. In the laboratory trial, the treatments consisted of two raw material sources with a low C/N ratio (castor bean bran-CAB and cottonseed bran-COB), corresponding to 40% of the mixture; three sources with a high C/N ratio (wheat bran-WHB or rice bran-RIB), gradually replaced by passion fruit peel bran-PFPB), corresponding to 60% of the mixture. The materials were mixed, moistened, inoculated with microorganisms (Embiotic®) and kept in sealed containers with a capacity of 620 cm3 for 21 days. In the greenhouse, in addition to the aforementioned treatments, seven controls were included: no addition of organic and synthetic N sources; ammonium nitrate; CAB; COB; WHB; RIB and PFPB. In the second stage, dry mass production and N content in sorghum plant tissues were determined, and the rates of N availability were estimated. It was found that the pH of the standard compost was 4.75, and in the other formulations it ranged from 4.62 to 5.3, the highest values being observed when WHB was fully replaced by RIB There was a significant difference in the EC values, but all were well below the value considered adequate. Replacing CAB with COB and WHB with RIB and PFPB resulted in a reduction in N content and an increase in the C:N ratio. Replacing WHB with PFPB led to an increase in K content and a reduction in P and Mg content. In the bioassay, the highest biomass production was in the treatments with the fermented composts, and the highest biological recovery of N was obtained in the ammonium nitrate treatment, followed by the CAB, COB and WHB treatments.

Performance of microbial inoculation and tricalcium phosphate on nitrogen retention and conversion: Core microorganisms and enzyme activity during kitchen waste composting

The substantial release of NH3 during composting leads to nitrogen (N) losses and poses environmental hazards. Additives can mitigate nitrogen loss by adsorbing NH3/NH4, adjusting pH, and enhancing nitrification, thereby improving compost quality. Herein, we assessed the effects of combining bacterial inoculants (BI) (1.5%) with tricalcium phosphate (CA) (2.5%) on N retention, organic N conversion, bacterial biomass, functional genes, network patterns, and enzyme activity during kitchen waste (KW) composting. Results revealed that adding of 1.5%/2.5% (BI + CA) significantly (p < 0.05) improved ecological parameters, including pH (7.82), electrical conductivity (3.49 mS/cm), and N retention during composting. The bacterial network properties of CA (265 node) and BI + CA (341 node) exhibited a substantial niche overlap compared to CK (210 node). Additionally, treatments increased organic N and total N (TN) content while reducing NH4+-N by 65.42% (CA) and 77.56% (BI + CA) compared to the control (33%). The treatments, particularly BI + CA, significantly (p < 0.05) increased amino acid N, hydrolyzable unknown N (HUN), and amide N, while amino sugar N decreased due to bacterial consumption. Network analysis revealed that the combination expanded the core bacterial nodes and edges involved in organic N transformation. Key genes facilitating nitrogen mediation included nitrate reductase (nasC and nirA), nitrogenase (nifK and nifD), and hydroxylamine oxidase (hao). The structural equation model suggested that combined application (CA) and microbial inoculants enhance enzyme activity and bacterial interactions during composting, thereby improving nitrogen conversion and increasing the nutrient content of compost products.

Optimization of organic solid waste composting process through iron-related additives: A systematic review

Composting is an environmentally friendly method that facilitates the biodegradation of organic solid waste, ultimately transforming it into stable end-products suitable for various applications. The element iron (Fe) exhibits flexibility in form and valence. The typical Fe-related additives include zero-valent-iron, iron oxides, ferric and ferrous ion salts, which can be targeted to drive composting process through different mechanisms and are of keen interest to academics. Therefore, this review integrated relevant literature from recent years to provide more comprehensive overview about the influence and mechanisms of various Fe-related additives on composting process, including organic components conversion, humus formation and sequestration, changes in biological factors, stability and safety of composting end-products. Meanwhile, it was recommended that further research be conducted on the deep action mechanisms, biochemical pathways, budget balance analysis, products stability and application during organic solid waste composting with Fe-related additives. This review provided guidance for the subsequent targeted application of Fe-related additives in compost, thereby facilitating cost reduction and promoting circular economy objectives.

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.

A change in substance and microbial community structure during the co-composting of kitchen waste anaerobic digestion effluent, sewage sludge and Chinese medicine residue

Anaerobic digestion is a resource recovery method for organic waste, gaining attention due to carbon reduction. Disposing of anaerobic digestion effluent (ADE) is crucial for developing anaerobic digestion, but conventional wastewater treatment fails to effectively recover nutrients contained in the ADE. In the present study, the ADE without solid-liquid separation was mixed with sewage sludge and Chinese medicine residue for the composting, where the ADE could be recovered at high temperature through humification. Besides, the nitrogen balance, humification process, and microbial dynamics during the composting process were studied. The results showed that the group supplemented with ADE could increase the nitrogen retention efficiency by 2.21 % compared to the control group. High ammonia nitrogen content and salinity did not negatively affect the maturity and phytotoxicity of compost products and even increase the humification degree of compost products. Moreover, additional ADE may not alter microbial community structure, which could contribute to microbial succession. This is the first time to investigate the substance transformation and shift in microbial community structure while applying composting process for ADE treatment, in which the anaerobic-aerobic collaborative disposal process provides an alternative solution for the recovery of ADE.

Co-inoculation of phosphate-solubilizing bacteria and phosphate accumulating bacteria in phosphorus-enriched composting regulates phosphorus transformation by facilitating polyphosphate formation

This study aimed to explore the impact of co-inoculating phosphate-solubilizing bacteria (PSB) and phosphate accumulating bacteria (PAB) on phosphorus forms transformation, microbial biomass phosphorus (MBP) and polyphosphate (Poly-P) accumulation, bacterial community composition in composting, using high throughput sequencing, PICRUSt 2, network analysis, structural equation model (SEM) and random forest (RF) analysis. The results demonstrated PSB-PAB co-inoculation (T1) reduced Olsen-P content (1.4 g) but had higher levels of MBP (74.2 mg/kg) and Poly-P (419 A.U.) compared to PSB-only (T0). The mantel test revealed a significantly positive correlation between bacterial diversity and both bioavailable P and MBP. Halocella was identified as a key genus related to Poly-P synthesis by network analysis. SEM and RF analysis showed that pH and bacterial community had the most influence on Poly-P synthesis, and PICRUSt 2 analysis revealed inoculation of PAB increased ppk gene abundance in T1. Thus, PSB-PAB co-inoculation provides a new idea for phosphorus management.

Microbiome data analysis via machine learning models: Exploring vital players to optimize kitchen waste composting system

Composting, reliant on microorganisms, effectively treats kitchen waste. However, it is difficult to precisely understand the specific role of key microorganisms in the composting process by relying solely on experimental research. This study aims to employ machine learning models to explore key microbial genera and to optimize composting systems. After introducing a novel microbiome preprocessing approach, Stacking models were constructed (R2 is about 0.8). The SHAP method (SHapley Additive exPlanations) identified Bacillus, Acinetobacter, Thermobacillus, Pseudomonas, Psychrobacter, and Thermobifida as prominent microbial genera (Shapley values ranging from 3.84 to 1.24). Additionally, microbial agents were prepared to target the identified key genera, and experiments demonstrated that the composting quality score was 76.06 for the treatment and 70.96 for the control. The exogenous agents enhanced decomposition and improved compost quality in later stages. In summary, this study opens up a new avenue to identifying key microorganisms and optimizing the biological treatment process.

In vitro screening and characterization of lactic acid bacteria from Lithuanian fermented food with potential probiotic properties

The present work aimed to identify probiotic candidates from Lithuanian homemade fermented food samples. A total of 23 lactic acid bacteria were isolated from different fermented food samples. Among these, only 12 showed resistance to low pH, tolerance to pepsin, bile salts, and pancreatin. The 12 strains also exhibited antimicrobial activity against Staphylococcus aureus ATCC 29213, Salmonella Typhimurium ATCC 14028, Streptococcus pyogenes ATCC 12384, Streptococcus pyogenes ATCC 19615, and Klebsiella pneumoniae ATCC 13883. Cell-free supernatants of isolate 3A and 55w showed the strongest antioxidant activity of 26.37 μg/mL and 26.06 μg/mL, respectively. Isolate 11w exhibited the strongest auto-aggregation ability of 79.96% as well as the strongest adhesion to HCT116 colon cells (25.671 ± 0.43%). The selected strains were tested for their synbiotic relation in the presence of a prebiotic. The selected candidates showed high proliferation in the presence of 4% as compared to 2% galactooligosaccharides. Among the strains tested for tryptophan production ability, isolate 11w produced the highest L-tryptophan levels of 16.63 ± 2.25 μm, exhibiting psychobiotic ability in the presence of a prebiotic. The safety of these strains was studied by ascertaining their antibiotic susceptibility, mucin degradation, gelatin hydrolysis, and hemolytic activity. In all, isolates 40C and 11w demonstrated the most desirable probiotic potentials and were identified by 16S RNA and later confirmed by whole genome sequencing as Lacticaseibacillus paracasei 11w, and Lactiplantibacillus plantarum 40C: following with the harboring plasmid investigation. Out of all the 23 selected strains, only Lacticaseibacillus paracasei 11w showed the potential and desirable probiotic properties.

Comparison of the basic processes of aerobic, anaerobic, and aerobic-anaerobic coupling composting of Chinese medicinal herbal residues

Chinese medicinal herbal residues (CMHRs) are waste generated after extracting Chinese medicinal materials, and they can be used as a renewable bioresource. This study aimed to evaluate the potential of aerobic composting (AC), anaerobic digestion (AD), and aerobic-anaerobic coupling composting (AACC) for the treatment of CMHRs. CMHRs were mixed with sheep manure and biochar, and composted separately under AC, AD, and AACC conditions for 42 days. Physicochemical indices, enzyme activities, and bacterial communities were monitored during composting. Results showed that AACC- and AC-treated CMHRs were well-rotted, with the latter exhibiting the lowest C/N ratio and maximal germination index (GI) values. Higher phosphatase and peroxidase activities were detected during the AACC and AC treatments. Better humification was observed under AACC based on the higher catalase activities and lower E4/E6. AC treatment was effective in reducing compost toxicity. This study provides new insights into biomass resource utilisation.

The driving mechanism of passivator islands adsorbing and immobilizing heavy metals during chicken manure composting

The aim of this study was to assess the effectiveness of biochar and montmorillonite islands on heavy metal adsorptive immobilization and identify crucial driving factors and pathways during chicken manure composting. Compared to montmorillonite (6.74 and 89.25 mg/kg), biochar exhibited an obviously higher ability of Cu and Zn enrichment (41.79 and 167.77mg/kg), might be attributed to its abundant active functional groups. Network analysis showed that compared to Cu, core bacteria positively and negatively related to Zn was obviously more and less in passivator islands, respectively, which might explain significantly higher Zn concentration. Structural Equation Model displayed that dissolved organic carbon (DOC), pH and bacteria were critical driving factors. Pretreatment of passivator packages, such as soaking in the solution being rich in DOC and inoculating specific microbial agents accumulating heavy metals via extracellular adsorption /intracellular interception would significantly improve the effectiveness of adsorptive passivation on heavy metals.

Reducing nitrogen loss during kitchen waste composting using a bioaugmented mechanical process with low pH and enhanced ammonia assimilation

Exploring the regulation of nitrogen transformation in bioaugmented mechanical composting (BMC) process for rural kitchen waste (KW) is essential to avoid the "not-in-my-backyard" phenomenon caused by nitrogen loss. Herein, nitrogen transformation and loss in BMC versus conventional pile composting (CPC) of KW were compared. The results showed that the total nitrogen loss in the BMC was 6.87-39.32 % lower than that in the CPC. The main pathways to prevent nitrogen loss in the BMC were reducing NH₃ by avoiding a sharp increase in pH followed by transforming the preserved NH₄⁺-N into recalcitrant nitrogen reservoir via enhanced ammonia assimilation. The enriched thermophilic bacteria with mineralization capacities (e.g., Bacillus and Corynebacterium) during rapid dehydration and heating in the BMC accumulated organic acids and easy-to-use carbon sources, which could lead to lower pH and ammonia assimilation enhancement, respectively. This study provides new ideas for formulating low-cost nitrogen conservation strategies in decentralized KW composting.

Identification of microorganisms from fermented biowaste and the potential for wastewater treatment

Food loss or waste is a far-reaching problem and has indeed become a worrying issue that is growing at an alarming rate. Fruits and vegetables are lost or wasted at the highest rate among the composition of food waste. Furthermore, the world is progressing toward sustainable development; hence, an efficient approach to valorise fruit and vegetable waste (FVW) is necessary. A simple phenotypic characterisation of microbiota isolated from the fermented FVW was conducted, and its effectiveness toward wastewater treatment was investigated. Presumptive identification suggested that yeast is dominant in this study, accounting for 85% of total isolates. At the genus level, the enriched medium's microbial community consists of Saccharomyces, Bacillus and Candida. Ammonium in the wastewater can enhance certain bacteria to grow, such as lactic acid bacteria, resulting in decreased NH₄⁺ concentration at the end of the treatment to 0.5 mg/L. In addition, the fermented biowaste could reduce PO₄^3- by 90% after the duration of treatment. Overall, FVW is a valuable microbial resource, and the microbial population enables a reduction in organic matter such as NH₄⁺ and PO₄^3-. This study helps explore the function and improve the effectiveness of utilising biowaste by understanding the microorganisms responsible for producing eco-enzyme.

Combined addition of biochar, lactic acid, and pond sediment improves green waste composting

Composting, as an eco-friendly method to recycle green waste (GW), converts the GW into humus-like compounds. However, conventional GW composting is inefficient and generates poor-quality compost. The objective of this research was to investigate the effects of the combined additions of biochar (BC; 0, 5, and 10 %), lactic acid (LA; 0, 0.5, and 1.0 %), and pond sediment (PS; 0, 20, and 30 %) on GW composting. A treatment without additives served as the control (treatment T1). The results showed that treatment R1 (with 5 % BC, 0.5 % LA, and 20 % PS) was better than the treatments with two additives or no additive and required only 32 days to generate a stable and mature product. Compared with T1, R1 improved water-holding capacity, electrical conductivity, available phosphorus, available potassium, nitrate nitrogen, OM decomposition, and germination index by 51 %, 48 %, 170 %, 93 %, 119 %, 157 %, and 119 %, respectively. R1 also increased the activities of cellulase, lignin peroxidase, and laccase. The results showed that the combined addition of BC, LA, and PS increased the gas exchange, water retention, and the microbial secretion of enzymes, thus accelerating the decomposition of GW. This study demonstrated the effects of BC, LA, and PS addition on GW composting and final compost properties, and analyzed the reasons of the effects. The study therefore increases the understanding of the sustainable disposal of an important solid waste.

Independent and combined effects of biochar and microbial agents on physicochemical parameters and microbial community succession during food waste composting

This study evaluated the independent and combined effects of biochar and microbial agents on food waste composting. The results indicated that combined addition increased the peak temperature to 63.5 °C and extended the thermophilic periods to 8 days, resulting in the highest organic matter degradation rate (12.7%). Analysis of enzymatic activity indicated that combined addition increased urease and dehydrogenase activity by 22.9% and 26.5%. Furthermore, the degradation of volatile fatty acids also increased by 37.4% with combined addition. Microbial analysis demonstrated that combined addition effectively increased the relative abundances of Enterobacter, Sphingobacterium and Aspergillus, which could be attributed to the optimal environment provided by biochar and stimulation of microbial agents. Moreover, correlation analysis showed a strong interaction between the microbial community and environment with combined addition. In general, combined addition could be beneficial for composting based on the synergistic effects of biochar and inoculation on microorganism.

Phytotoxicity of farm livestock manures in facultative heap composting using the seed germination index as indicator

Static facultative heap composting of animal manure is widely used in China, but there is almost no systematic research on the phytotoxicity of the produced compost. Here, we evaluated the phytotoxic variation in compost produced by facultative heap composting of four types of animal manure (chicken manure, pig manure, sheep manure, and cattle manure) using different plant seeds (cucumber, radish, Chinese cabbage, and oilseed rape) to determine germination index (GI). The key factors that affected GI values were identified, including the dynamics of the phytotoxicity and microbial community during heap composting. Sensitivity to toxicity differed depending on the type of plant seed used. Phytotoxicity during facultative heap composting, evaluated by the GI, was in the order: chicken manure (0-6.6 %) < pig manure (14.4-90.5 %) < sheep manure (46.0-93.0 %) < cattle manure (50.2-105.8 %). Network analysis showed that the volatile fatty acid (VFA) concentration was positively correlated with Firmicutes abundance, and NH₄⁺-N was correlated with Actinobacteria, Proteobacteria, and Bacteroidetes. More bacteria were stimulated to participate in conversions of dissolved organic carbon, dissolved nitrogen, VFA, and ammonia-nitrogen (NH₄⁺-N) in sheep manure heap composting than that in other manure. The GI was most affected by VFA in chicken manure and cattle manure heap composting, while NH₄⁺-N was the main factor affecting the GI in pig manure and sheep manure compost. The dissolved carbon and nitrogen content and composition, as well as the core and proprietary microbial communities, were the primary factors that affected the succession of phytotoxic substances in facultative heap composting, which in turn affected GI values. In this study, the key pathways of livestock manure composting that affected GI and phytotoxicity were found and evaluated, which provided new insights and theoretical support for the safe use of organic fertilizer.

Bacterial dynamics for gaseous emission and humification during bio-augmented composting of kitchen waste with lime addition for acidity regulation

This study investigated the impacts of lime addition and further microbial inoculum on gaseous emission and humification during kitchen waste composting. High-throughput sequencing was integrated with Linear Discriminant Analysis Effect Size (LEfSe) and Functional Annotation of Prokaryotic Taxa (FAPROTAX) to decipher bacterial dynamics in response to different additives. Results showed that lime addition enriched bacteria, such as Taibaiella and Sphingobacterium as biomarkers, to strengthen organic biodegradation toward humification. Furthermore, lime addition facilitated the proliferation of thermophilic bacteria (e.g. Bacillus and Symbiobacterium) for aerobic chemoheterotrophy, leading to enhanced organic decomposition to trigger notable gaseous emission. Such emission profile was further exacerbated by microbial inoculum to lime-regulated condition given the rapid enrichment of bacteria (e.g. Caldicoprobacter and Pusillimonas as biomarkers) for fermentation and denitrification. In addition, microbial inoculum slightly hindered humus formation by narrowing the relative abundance of bacteria for humification. Results from this study show that microbial inoculum to feedstock should be carefully regulated to accelerate composting and avoid excessive gaseous emission.

Composting effect and antibiotic removal under a new temperature control strategy

The main objective of this study was to investigate the feasibility of a new temperature control strategy in the co-composting process to accelerate operation cycle and remove antibiotics from mixed organic wastes. The evaluation of the composting process showed that composting with temperature control (TC) was completed within 14 days. The final compost of TC exhibited a 10% higher degradation of organic matters, more humus formation and 11.25% lower heavy metals concentration than conventional composting (CC), which fully met the Chinese National Agricultural Organic Fertilizer Standard requirements. The degradation extent and kinetic of macrolides, tetracyclines, sulfonamides and fluoroquinolones showed that the removal efficiency of total antibiotics in TC was 23.58% higher than CC, with less half-life, which was significantly correlated with higher temperature. Particularly, the highest removal was observed for sulfonamides (87.45%) in TC, the half-life of which was reduced by 75.95% compared with CC. The higher degradation rate was attributed to enhanced decomposition of unstable antibiotics and degrading activity of microbes at high temperature. The microbiological analysis showed that the external heating led to a distinct composition and succession of bacterial community in TC. Firmicutes, Proteobacteria, Actinobacteriota and Bacteroidota were dominant and the emergence of Patescibacteria and Chloroflexi at cooling period in TC proved that the later composting environment was in an oligotrophic state. Current research provided a promising rapid composting approach for high-quality fertilizer production and antibiotic management in organic waste disposal.

Dynamics of Microbial Community during the Co-Composting of Swine and Poultry Manure with Spent Mushroom Substrates at an Industrial Scale

Spent mushroom substrates (SMSs) can be developed as a biofertilizer through composting. Here, we investigated the dynamics of bacterial and fungal communities during commercial composting and the effect of swine and poultry manure on their communities through MiSeq pyrosequencing. Weissella paramesenteroides and Lactobacillus helveticus were dominant bacterial species in the composts with soy waste (SMS-SW), whereas Thermotogaceae sp. and Ureibacillus sp. were dominant in the composts with swine and poultry manure (SMS-PM). For the fungal community, Flammulina velutipes was dominant in SMS-SW, whereas Trichosporon asahii, Candida catenulate, Aspergillus fumigatus, and Candida tropicalis were dominant in SMS-PM. The addition of manure affected the bacterial community significantly. Redundancy analysis indicated that bacterial communities were affected by temperature, potassium, and potassium oxide and fungal communities by temperature, Kjeldahl nitrogen, organic matter, and ammonium nitrogen. Our findings can guide future research on composting microbiology.

Exploring the dynamic of microbial community and metabolic function in food waste composting amended with traditional Chinese medicine residues

The aim of this study was to explore the dynamic of microbial community and metabolic function in food waste composting amended with traditional Chinese medicine residues (TCMRs). Results suggested that TCMRs addition at up to 10% leads to a higher peak temperature (60.5 °C), germination index (GI) value (119.26%), and a greater reduction in total organic carbon (TOC) content (8.08%). 10% TCMRs significantly induced the fluctuation of bacterial community composition, as well as the fungal community in the thermophilic phase. The addition of 10% TCMRs enhanced the abundance of bacterial genera such as Acetobacter, Bacillus, and Brevundimonas, as well as fungal genera such as Chaetomium, Thermascus, and Coprinopsis, which accelerated lignocellulose degradation and humification degree. Conversely, the growth of Lactobacillus and Pseudomonas was inhibited by 10% TCMRs to weaken the acidic environment and reduce nitrogen loss. Metabolic function analysis revealed that 10% TCMRs promoted the metabolism of carbohydrate and amino acid, especially citrate cycle, glycolysis/gluconeogenesis, and cysteine and methionine metabolism. Redundancy analysis showed that the carbon to nitrogen (C/N) ratio was the most significant environmental factor influencing the dynamic of bacterial and fungal communities.

Improving kitchen waste composting maturity by optimizing the processing parameters based on machine learning model

As a novel analytical method based on big data, machine learning model can explore the relationship between different parameters and draw universal conclusions, which was used to predict composting maturity and identify key parameters in this study. The results showed that the Stacking model exhibited excellent prediction accuracy. SHapley Additive exPlanations (SHAP) and Partial Dependence Analysis (PDA) were performed to evaluate the importance of different parameters as well as their optimal interval. Optimal starting conditions should be maintained in the mesophilic state (temperature: 30-45℃, moisture content: 55-65%, pH: 6.3-8.0), and nutrients (total nitrogen > 2.3%, total organic carbon > 35%) should be adjusted in the thermophilic state. Experiments revealed that model-based optimization strategies could improve composting maturity because they could optimize compost microbial flora and perform complex carbon cycle functions. In conclusion, this study provides new insights into the enhancement of the composting process.

Deciphering the internal driving mechanism of microbial community for carbon conversion and nitrogen fixation during food waste composting with multifunctional microbial inoculation

In this study, the effects of multifunctional microbial inoculation on food waste composting based on the synergistic property between organic matter degradation and nitrogen fixation were investigated. The results showed that inoculation simultaneously strengthened organic matter degradation by 9.9% and improved the nitrogen content by 20.6% compared with that of the control group. Additionally, spectral analysis demonstrated that inoculation was conducive to the enhanced humification, which was supported by the improvement in polyphenol oxidase activity. Microbial analysis showed that most of the introduced microorganisms (Bacillus, Streptomyces, Saccharomonospora) successfully colonized, and stimulated the growth of other indigenous microorganisms (Enterobacter, Paenibacillus). Meanwhile, the change in microbial community structure was accompanied by the enhanced tricarboxylic acid cycle and amino acid metabolism. Furthermore, network analysis and structural equation model revealed that the enhanced cooperation of microorganisms, in which more carbon sources could be provided by cellulose decomposition for nitrogen fixation.

Dynamics and key drivers of antibiotic resistance genes during aerobic composting amended with plant-derived and animal manure-derived biochars

Plant-derived and animal manure-derived biochars have been used to improve the quality of compost but the differences in their effects on antibiotic resistance genes (ARGs) during composting are unclear. This study selected two types of biochar (RB and PB) produced from abundant agricultural waste to be added to the compost. Adding plant-derived RB performed better in ARGs, mobile genetic elements, and human pathogenic bacteria removal during aerobic composting, whereas adding manure-derived PB even increased ARGs abundance. Vertical gene transfer was possibly the key mechanism for persistent ARGs, and easily removed ARGs were regulated by horizontal and vertical gene transfer. Adding plant-derived RB reduced the abundances of persistent ARG hosts (e.g., Pseudomonas and Longispora) and ARG-related metabolic pathways and genes. The higher nitrogen content of manure-derived PB may have promoted the proliferation of ARG hosts. Overall, adding manure-derived biochar during composting may not be the optimal option for eliminating ARGs.

Insights into the effect of iron-carbon particle amendment on food waste composting: Physicochemical properties and the microbial community

The effects of iron-carbon (Fe-C) particle amendment on organic matter degradation, product quality and functional microbial community in food waste composting were investigated. Fe-C particles (10%) were added to the material and composted for 32 days in a lab-scale composting system. The results suggested that Fe-C particle enhanced organic matter degradation by 12.3%, particularly lignocellulose, leading to a greater humification process (increased by 15.5%). In addition, NO₃^--N generation was enhanced (15.9%) by nitrification with more active ammonia monooxygenase and nitrite oxidoreductase activities in the cooling and maturity periods. Fe-C particles not only significantly increased the relative abundances of Bacillus and Aspergillus for organic matter decomposition, but also decreased the relative abundances of acid-producing bacteria. RDA analysis demonstrated that the bacterial community was significantly influenced by dissolved organic matter, C/N, NO₃^--N, humic acid, volatile fatty acids and pH, while electrical conductivity was the key factor affecting the fungal community.

Bacterial dynamics for gaseous emission and humification in bio-augmented composting of kitchen waste

Using high-throughput sequencing and Functional Annotation of Prokaryotic Taxa (FAPROTAX), this study aimed to elucidate the effect of bacterial dynamics on gaseous emission and humification of kitchen and garden wastes during composting augmented with microbial inoculants. Microbial inoculant addition at up to 0.9% resulted in a diverse bacterial community with more functional bacteria to amend gaseous emission and enhance humification. Microbial inoculation facilitated the enrichment of aerobic bacteria (e.g. the genus Bacillus and Thermobifida) to enhance cellulolysis and ligninolysis to advance organic humification. By contrast, several bacteria, such as the genus Weissella and Pusillimonas were inhibited by microbial inoculation to weaken fermentation and nitrate respiration. As such, bio-augmented composting with 0.9% microbial inoculant reduced the emission of methane by 11-20% and nitrogen oxide by 17-54%. On the other hand, ammonia and hydrogen sulphide emissions increased by 26-62% and 5-23%, respectively, in bio-augmented composting due to the considerable proliferation of the genus Bacillus and Desulfitibacter to enhance ammonification and sulphur-related respiration. Results from this study highlight the need to further develop efficient and multifunctional microbial inoculants that promote humification and deodorization for bio-augmented composting of kitchen waste as well as other carbon and nutrient rich organic wastes.

Valorization of municipal organic waste into purified lactic acid

Municipal organic waste (biowaste) consists of food derived starch, protein and sugars, and lignocellulose derived cellulose, hemicellulose, lignin and pectin. Proper management enables nutrient recycling and sustainable production of platform chemicals such as lactic acid (LA). This review gathers the most important information regarding use of biowaste for LA fermentation covering pre-treatment, enzymatic hydrolysis, fermentation and downstream processing to achieve high purity LA. The optimal approach was found to treat the two biowaste fractions separately due to different pre-treatment and enzyme needs for achieving enzymatic hydrolysis and to do continues fermentation to achieve high cell density and high LA productivity up to 12 g/L/h for production of both L and D isomers. The specific productivity was 0.4 to 0.5 h^-1 but with recalcitrant biomass, the enzymatic hydrolysis was rate limiting. Novel purification approaches included reactive distillation and emulsion liquid membrane separation yielding purities sufficient for polylactic acid production.

Bacterial dynamics and functions driven by bulking agents to mitigate gaseous emissions in kitchen waste composting

This study investigated the impacts of different bulking agents (i.e. garden waste, cornstalks, and spent mushroom substrates) on bacterial structure and functions for gaseous emissions during kitchen waste composting. High-throughput sequencing was integrated with functional Annotation of Prokaryotic Taxa (FAPROTAX) to decipher the bacterial structure and functions. Results show that adding cornstalks constructed a more complex and mutualistic bacterial network to enhance organic biodegradation. This scenario, however, aggravated the emission of ammonia and hydrogen sulphide with the enrichment of the genus Bacillus and Desulfitibacter at the thermophilic stage of composting to facilitate ammonification and sulphur-related respiration, respectively. By contrast, spent mushroom substrates facilitated the proliferation of the genus Pseudomonas to promote nitrate reduction at the cooling stage, leading to considerable emission of nitrous oxide. Compared to these two agents, garden waste contained less easily biodegradable substances to limit bacterial mutualism, thereby reducing gaseous emissions in composting.

Insight into the mechanisms of insoluble phosphate transformation driven by the interactions of compound microbes during composting

Phosphate-solubilizing (PS) microbes are important to improve phosphorus availability and transformation of insoluble phosphate, e.g., rock phosphate (RP). The use of phosphate solubilizing bacteria (PSB) as inoculants have been proposed as an alternative to increase phosphate availability in RP and composting fertilizers. In this study, the effect of compound PSB coinoculation and single-strain inoculation on the transformation of insoluble phosphate were compared in a liquid medium incubation and RP-enriched composting. The goal of this study was to understand the possible mechanisms of insoluble phosphate transformation driven by the interactions of compound PS microbes during composting. The correlations between organic acids production, P-solubilization capacity and bacterial community with PSB inoculation were investigated in the RP-enriched composting by redundancy analysis (RDA) and structural equation models (SEM). Results showed that both single-strain and compound PSB inoculants had a high P-solubilization capacity in medium, but the proportion of Olsen P to total P in composts with inoculating compound PS microbes was 7% higher than that with single strain. PS inoculants could secrete different organic acids and lactic was the most abundant. However, RDA and SEM suggested that oxalic might play an important role on PS activity, inducing RP solubilization by changing pH during composting. Interaction between compound microbes could intensify the acidolysis process for insoluble P transformation compared to the single strain. Our findings help to understand the roles of complex microbial inoculants and regulate P availability of insoluble phosphate for the agricultural purposes.

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

Waste biomass coming from a local coffee company, which supplied burnt ground coffee after an incorrect roasting process, was employed as a starting material in the composting plant of the Experimental Station of the University of Naples Federico II at Castel Volturno (CE). The direct molecular characterization of compost using ¹³C-NMR spectra, which was acquired through cross-polarization magic-angle spinning, showed a hydrophobicity index of 2.7% and an alkyl/hydroxyalkyl index of 0.7%. Compost samples that were collected during the early "active thermophilic phase" (when the composting temperature was 63 °C) were analyzed for the prokaryotic community composition and activities. Two complementary approaches, i.e., genomic and predictive metabolic analysis of the 16S rRNA V3-V4 amplicon and culture-dependent analysis, were combined to identify the main microbial factors that characterized the composting process. The whole microbial community was dominated by Firmicutes. The predictive analysis of the metabolic functionality of the community highlighted the potential degradation of peptidoglycan and the ability of metal chelation, with both functions being extremely useful for the revitalization and fertilization of agricultural soils. Finally, three biotechnologically relevant Firmicutes members, i.e., Geobacillus thermodenitrificans subsp. calidus, Aeribacillus pallidus, and Ureibacillus terrenus (strains CAF1, CAF2, and CAF5, respectively) were isolated from the "active thermophilic phase" of the coffee composting. All strains were thermophiles growing at the optimal temperature of 60 °C. Our findings contribute to the current knowledge on thermophilic composting microbiology and valorize burnt ground coffee as waste material with biotechnological potentialities.

An high-throughput sequencing approach to the preliminary analysis of bacterial communities associated with changes in amino acid nitrogen, organic acid and reducing sugar contents during soy sauce fermentation

Soy sauce is a traditional fermented soy food for enhancing the umami taste in Asian cuisines. In this study, 16S rRNA gene throughput sequencing analysis showed the bacterial communities and the changes in soy sauce during fermentation. Weissella, Bacillus and Lactococcus were the most abundant at genus level. The uncultured bacterium Weissella and Lactococcus had relatively high abundance at species level. Alpha diversity analysis indicated the bacterial community diversity increased at fermentation initiation, while decreased as fermentation progressed. Based on beta-diversity analysis, four clusters including cluster I (time point A-F), cluster II (G,H), cluster III (I,J) and cluster IV(K) were distinctly separated, indicating the fermentation time significantly affected bacterial community diversity. Also, close associations were found between the bacterial communities in soy sauce and its amino acid nitrogen, organic acid and reducing sugar contents during fermentation. Therefore, it will provide important information for optimization of the soy sauce production process.

Metagenomic analysis reveals enhanced biodiversity and composting efficiency of lignocellulosic waste by thermoacidophilic effective microorganism (tEM)

Composting is a microbiological process that converts organic waste into organic soil amendment. We reveal enhanced biodiversity and microbial population with subsequent enhancement of composting efficiency of lignocellulosic waste using thermoacidophilic effective microorganisms (tEM). Composting with tEM + shading (tEMA) or tEM without shading (tEMB) increased the average microbial population by 12.0% or 6.7%, respectively compared to non-tEM composting without shading/control (C). The biodiversity in tEMA or tEMB treated groups was increased by 34.7% or 43.7%, respectively, compared to C. The highest increase in population (31.7% and 9.4%) and diversity (91.2% and 91.6%) were observed in tEMA and tEMB at 30 d, respectively. Regarding microbial structure, the most dominant phylum shifted from Proteobacteria to Bacteroidetes during composting. From 60 to 120 d, tEM notably improved the average abundance of Firmicutes (mainly Bacillus) by 166.7% and 75.8% in tEMA and tEMB groups, respectively. The overall gradation rate of large compost granules (<2 mm) increased by 36.4% and 24.7%, following tEMA and tEMB treatment, respectively. The average rate of increase in bulk density was 42.6% or 33.3% by tEMA or tEMB, respectively, compared to C. We reveal the major differences in microbial structure, including a higher abundance of beneficial microbes like Bacillus in tEM treated composts. The study revealed that tEM could improve biodiversity and population of microbes, especially during thermophilic phase (above 45 °C), with a subsequent increase in composting rate, mineralization, and product quality. The results of this study are particularly invaluable in the areas of environmental conservation and organic agriculture.

Lactic acid production - producing microorganisms and substrates sources-state of art

Lactic acid is an organic compound produced via fermentation by different microorganisms that are able to use different carbohydrate sources. Lactic acid bacteria are the main bacteria used to produce lactic acid and among these, Lactobacillus spp. have been showing interesting fermentation capacities. The use of Bacillus spp. revealed good possibilities to reduce the fermentative costs. Interestingly, lactic acid high productivity was achieved by Corynebacterium glutamicum and E. coli, mainly after engineering genetic modification. Fungi, like Rhizopus spp. can metabolize different renewable carbon resources, with advantageously amylolytic properties to produce lactic acid. Additionally, yeasts can tolerate environmental restrictions (for example acidic conditions), being the wild-type low lactic acid producers that have been improved by genetic manipulation. Microalgae and cyanobacteria, as photosynthetic microorganisms can be an alternative lactic acid producer without carbohydrate feed costs. For lactic acid production, it is necessary to have substrates in the fermentation medium. Different carbohydrate sources can be used, from plant waste as molasses, starchy, lignocellulosic materials as agricultural and forestry residues. Dairy waste also can be used by the addition of supplementary components with a nitrogen source.

Assessment of Used Baby Diapers Composting in Bolivia

Solid waste open dumping in developing countries is a global concern. To move towards sustainable development, mixed waste should be reduced, and recyclable waste recovered. The aim of the current research was to find appropriate solutions to disposable used baby-diapers recycling in Bolivia since it is a waste fraction widely produced and commonly disposed of in open dumps. Composting of the organic diaper hydrogel was assessed in five trials, adding components available locally: cow dung, activated bacteria, and Californian red earthworms (Eisenia fetida). It was observed that about 60 days were globally required for biomass decomposition with cow dung, activated bacteria, and earthworms, and more than 70 days for the treatment of the substrate mixed only with manure, while the diaper hydrogel did not degrade without cow dung. This research is the first that attempted to treat disposable used baby diapers with the vermicomposting process. In general, the outcomes of the research are promising: vermicomposting with cow manure can be a recycling option for disposable used baby diapers, introducing appropriate practices toward a circular economy in developing regions.

Non-sterile fermentation of food waste with indigenous consortium and yeast - Effects on microbial community and product spectrum

This work presents examples of non-sterile mixed culture fermentation of food waste with a cultivated indigenous consortium (IC) gained from food waste, which produces lactic and acetic acids, combined with Saccharomyces cerevisiae, which produces ethanol. All results are flanked by microbial analysis to monitor changes in microbial community. At pH 6 and inoculated with yeast or IC, or both mixed sugars conversion was equal to 71%, 51%, or 67%, respectively. Under pH unregulated conditions metabolic yields were 71%, 67%, or up to 81%. While final titer of acetic acid was not affected by pH (100-200 mM), ethanol and lactic acid titers were. Using mixed culture and pH 6, sugars were almost equally used for formation of ethanol and lactic acid (400-500 mM). However, under pH unregulated conditions 80% of the substrate was converted into ethanol (900-1000 mM).

Microbes as vital additives for solid waste composting

Composting is a natural process that stems through microbial succession, marking the degradation and stabilization of organic matter present in waste. The use of microbial additives during composting is considered highly efficient, likely to enhance the production of different enzymes resulting in better rate of waste degradation. In lesser developed countries, composting has emerged as a vital technology to recycle the biodegradable waste while generating a useful product. Depending on the composition of the waste material, it can either directly undergo composting or homogenized prior to secondary waste treatment methods such as landfilling. However, a relatively expensive downstream handling all along is a main hurdle towards economics of the process. Although basic methodology and recent approaches are known in crucial aspects of the process through various reviews, exploring the behavior of effective microbial additives will be resourceful. In this review, to fill in the gap, studies related to microbial composting of municipal solid and food waste were acknowledged. Here in, factors that could slow down the composting process and affect the compost quality were addressed. Lastly, the review pictured a positive simulation and stated how excellent results, can be achieved by microbial additives during composting.