## 1 Introduction
The use of fresh bran in upland vegetable crops sometimes creates germination inhibition, as well as growth suppression of the crop [22]. However, the influence of these materials on microbial metabolism is not yet known. Considering the above facts, the use of rice bran compost could be a useful way for eco-friendly and non-chemical weed control in organic farming systems of upland vegetables [22]. Biochar is a carbonaceous material obtained from pyrolysis of biomass residues in the absence of oxygen [23]. The physicochemical, chemical, and microbiological properties of a composting pile are favorable for the interaction with biochar, and, consequently, it is expected that a synergy would be established between the pool of organic matter, nutrients, and microbial biomass of the composting material and the physicochemical properties of biochar [24]. The addition of biochar during composting had several benefits: reducing the compost toxicity, the compost exhibiting higher moisture content and lower waste density, N retention during composting, and decreasing potentially pathogenic microorganisms [25]. Co-application of wheat straw (WS) and wheat straw biochar (WSB) with nutrients (MF) at 1% and 2% doses enhanced carbon and nitrogen contents in soil (i.e., their water soluble fractions such as DOC and DON) [26]. The synergistic effect of biochar and MF triggered the increase in the population density and activity of soil microorganisms. The typical pathogens found in the composite of municipal solids waste and sewage sludge can be viruses, bacteria, protozoa, or helminths. They are usually heat-sensitive. The heat generated during the composting process can eliminate them, leading to a pathogen-free end compost product, and can be defined as a disinfection or sanitization process [27]. In an in-vessel composoting, _Salmonella_ sp., _Staphylococcus aureus_, and _Shigella_ sp. were removed, while the coliform counts were reduced by a 2-log scale after 40 days of composoting [28]. Antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs) were significantly removed by 22.8-99.7% during the thermophilic phase of composting facilitated by the compound microbial inoculants carrying _Bacillus_ sp. and yeasts [29]. This composting was helpful to remove the pathogen from the final compost product. Plant growth-promoting bacteria (PGPB) produce a wide variety of molecules, which improve plant growth and productivity. These PGPB increased the production of phyto-hormones or other molecules that protect plants from biotic and abiotic stress, increased mineral nutrition, modulating ethylene levels in plants and the production of volatile organic compounds [30]. Furthermore, PGPB act as a potential symbiont and degrades the xenobiotic compounds to protect the plants. Inoculation of PGPB along with a mixture of organic amendments and biochar could be an effective way to overcome the problem of heavy metal toxicity [31]. There have so far been few studies, to the best of our knowledge, regarding functional composts carrying PGPB and plant pathogen-inhibiting microbes. In this study, we aimed to manufacture and commercialize eco-friendly and high-quality functional composts using spent coffee grounds (and their extracts), biochar, rice bran, and functional microorganisms (plant growth-promoting bacteria and plant pathogen-inhibiting actinomycetes). We also tried to evaluate functional efficacies of the composts in terms of commercial application quality, microbial community structures, plant-growth promotion, antioxidant production in crops, and plant pathogen inhibition.