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Due to high oil content and complex composition, Kitchen waste (KW) is refractory for biotreatment and easily causes environmental burden, especially in Sichuan area with greasy cooking habits. To facilitate KW composting, a nitrogen-retaining & decomposing-promoting microbial agent (NRDPMA) was constituted with functional bacteria to decompose refractory substances, retain nutrients, and reduce gas emission. With NRDPMA, high-temperature period was achieved 2 days earlier and extended by 6 days, shorting the process by 15 days. 36.57% less NH 3 and 22.30% less H 2 S were released. The total nitrogen of the compost product was increased by 17.14%. Functional bacteria in NRDPMA (e. g. Bacillus , Pseudomonas , and Oceanobacillus) displayed obvious advantages throughout composting, which reshaped microbial community composition and drove material transformation. PICRUST2 prediction confirmed a higher gene occurrence related to metabolism of lipid, lignocellulose, and nitrogen. The great decomposing and transformation capacity made NRDPMA an alternative to improve the efficiency of composting on recycling such lipid-containing waste. And functional bacteria targeting refractory components should be included for biotreatment of waste. This study should give a new perspective on industrial KW composting. [Display omitted] • 6 days longer high-temperature period with 36.57% less NH 3 and 22.30% less H 2 S. • NRDPMA conserved 17.14% higher nitrogen with 15 days shorter composting period. • Functional bacteria of NRDPMA targeting lipid, starch, and cellulose played a crucial role. • NRDPMA participated in all the composting periods, drove microbial community change. [ABSTRACT FROM AUTHOR]

Nitrogen loss is the main problem in compost and controlling it is the key to the recovery and utilization of composted materials. This study systematically investigated the effect of nitrogen retaining microbial agent (NRMA) on nitrogen retention and the promotion of decay during manure composting and tested its effect on nitrogen conversion and bacterial community structure. During composting, various parameters were dynamically evaluated, including nitrogen loss and transformation, compost maturity and nutrient, microorganism population and bacteria community variation. Results showed that the inoculation of NRMA significantly reduced ammonia loss by 58.8% with 15 days shorter compost cycle. At the end of the composting, the total nitrogen (TN) and nitrate content of the experimental group were 23.3 g kg−1 and 4.5 g kg−1, 22.6% (p < 0.05) and 9.6% (p < 0.05) higher than those of the control group (19 g kg−1 and 4.1 g kg−1), respectively. In contrast, the ammonia emission and ammonium nitrogen in the experimental group (4.9 g and 1.4 g kg−1) were significant lower than those (11.9 g and 1.8 g kg−1) in the control group (p < 0.05). Nitrogen-transforming bacteria such as Paucisalibacillus , Sporosarcina, Sphingobacterium, and Oceanobacillus displayed obvious advantages at high temperatures, while Longispora and Luteivirga demonstrated clear benefits at the end of the compost. The mechanism of nitrogen loss reduction was proposed, which was regulated by the specific microorganisms in the compost, especially the strains from the NRMA. The strategy of addition NRMA shows great potential for industrial applications of manure compost, which could provide a novel alternative for the recovery of nitrogen resources from animal husbandry. [ABSTRACT FROM AUTHOR]