## 2 Materials and Methods  
Isolation and Selection of Plant Growth-Promoting Bacteria and Plant Pathogen Inhibiting Bacteria, and Their Growth Medium Preparation from Spent Coffee Grounds  
The target strains for this study were _Bacillus_ sp. (plant-growth-promotion function) and _Actinomyces_ sp. (plant-pathogen-suppression function) that were isolated from forest soils at the Korea Maritime and Ocean University (Busan, Korea) to identify microorganisms and register a patent strain. The media for _Bacillus_ sp. and _Actinomyces_ sp. were trypticase soy agar (TSA, Difco) and International Streptomyces Project (ISP-4), respectively. To establish a proper medium for the functional microorganisms, three kinds of extractions of coffee beans were tried: (1) spent coffee grounds suspended in distilled water (10%, \(w/w\)) and heat-treated (121 \({}^{\circ}\)C for 15 min); (2) spent coffee grounds suspended in distilled water (10%, \(w/w\)) and extracted in a shaking incubator (150 rpm) at 25 \({}^{\circ}\)C for 1 h; and (3) spent coffee grounds suspended in 80% ethanol (10%, \(w/w\)) and extracted in a shaking incubator (150 rpm) at 25 \({}^{\circ}\)C for 1 h. Each medium was tested to grow the potential functional microbial isolates (SB-3, SB-4, and St-3). The growth status (density and contamination degree) was monitored by plating the cultures onto TSA (SB-3 and SB-4) and ISP (St-3) for 4 days. The best medium was chosen based on the highest growth status. The potential plant-growth-promoting bacteria were selected based on radish germination activity and its seedling growth activity after growing 20 radish seeds on sterilized filter paper soaked with 2 mL of the bacterial culture grown on the best SCG extraction medium for 3 days. The plant-pathogen-suppressing bacteria (_Actinomyces_ sp.) were selected based on the growth inhibition effect of the bacteria (on ISP medium 4 agar plates) against known plant pathogens (_Fusarium oxysporum_ f. sp. _lycopesici_ KACC 40032, _Fusarium oxysporum_ f. sp. _lactuca_ KACC 42795, _Pythium ultimum_ KACC 40705, and _Pythium_ sp. KACC 40581). The final selected isolates were identified using the 16S rRNA gene analysis system at the Institute of Microbial Ecology and Resources, Mokwon University, Daejon, Korea. Procedures for Composting Using Spent Coffee Grounds, Rice Bran, and Biochar, and Phytotoxicity Test for the Manufactured Composts  
The substrates used for composting were spent coffee grounds, rice bran, and biochar. The spent coffee grounds were collected from several local coffee shops in Yeongdo-gu, Busan, Korea, and dried in a shaded place to 40-50% moisture. Recipes for substrates and microbial inoculum used for the composting at the laboratory and pilot scales are shown in Table 1, and the composting process is shown in Figure 1. The percentages of spent coffee grounds, rice bran, and biochar in the mixtures were 81.5% (\(w/w\)), 15.8%, and 2.5%, respectively, on the laboratory scale, and 49.07%, 49.28%, and 1.51%, respectively, on the pilot scale. The aerobic composting was performed by augmenting the microbial agent (MA-1) [15] as a facilitator for the composting, and the augmentation ratios were 0.2% (\(w/w\)) on the laboratory scale and 0.13% on the pilot scale. Each mixture was maintained under 50% moisture content at 50 \({}^{\circ}\)C for 7 days. Afterward, each compost was matured and stabilized by adding functional microbes (plant-growth-promoting bacteria and plant-pathogen-inhibiting bacteria) grown on SCG extract (10%, \(w/w\)) for 5 days. The moisture content (50%) and temperature (25-30 \({}^{\circ}\)C) were maintained for 7 days in the process. Two types of composting vessels were used on the laboratory scale: round plastic bucket type (depth \(\times\) height = 23 \(\times\) 29 cm) and rectangular plastic trays (length \(\times\) width \(\times\) height = 70 \(\times\) 50 \(\times\) 20 cm), all without a heat control system. The complete compost was dried to 40-50% moisture and kept at cool room temperature until the subsequent experiments.