Microbial community assembly during aging of food waste-derived hydrochar: key bacterial guilds mediate nutrient dynamics

Hydrochar aging may mitigate the adverse effects of direct application on plant growth. However, little is known about the strategies for accelerating this process and the microbiological mechanisms involved. This study explored the effects of three strategies, including the additions of straw and efficient-degrading microorganisms, on the aging processes of food waste-derived hydrochar, and the key microbial drivers. The bacterial and fungal community compositions in hydrochar were estimated at different aging periods (i.e., day 1, 7, 14 and 35) using 16S and ITS rRNA gene sequencing. The results showed that straw and microbial inoculum addition improved the temperature and shortened the aging time by [~]30%. Three bacterial guilds, mainly including Bacillus-like species, were identified that had significant correlations with the nitrogen (N) and phosphorus (P) dynamics during aging. This study demonstrates the feasibility of manipulating key microbial guilds artificially to achieve efficient harmless-treatment of hydrochar. HighlightsO_LIStraw and microbial inoculum addition reduced ageing duration by 30%. C_LIO_LIMicrobial inoculum addition increases the aging reaction temperature by 13%. C_LIO_LIBacteria, rather than fungi, play the critical role in hydrochar aging. C_LIO_LIBacillus and related species drive nitrogen and phosphorus cycles of aging. C_LI Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=155 SRC="FIGDIR/small/580608v1_ufig1.gif" ALT="Figure 1"> View larger version (68K): org.highwire.dtl.DTLVardef@b2c2c9org.highwire.dtl.DTLVardef@124ab1org.highwire.dtl.DTLVardef@e5c00borg.highwire.dtl.DTLVardef@1a31deb_HPS_FORMAT_FIGEXP M_FIG C_FIG