Enhancing food waste biodegradation rate in a food waste biodigester with the synergistic action of hydrolase-producing Bacillus paralicheniformis GRA2 and Bacillus velezensis TAP5 co-culture inoculation

Abstract EN

Food waste (FW) minimization at the source by using food waste biodigester (FWBs) has a vast potential to lower down the impact of increasing organic fraction in municipal solid waste generation.

To this end, this research sought to check the performance of locally isolated hydrolase-producing bacteria (HPB) to improve food waste biodegradation rate.

Two under-explored HPB identified as Bacillus paralicheniformis GRA2 and Bacillus velezensis TAP5 were able to produce maximum amylase, cellulase, protease and lipase activities, and demonstrated a significant hydrolase synergy in co-culture fermentation.

In vitro biodegra- dation analysis of both autoclaved and non-autoclaved FW revealed that the HPB inoculation was effec- tive to degrade total solids (>62%), protein (>19%), total fat (>51), total sugar (>86%), reducing sugar (>38%) and starch (>50%) after 8-day incubation.

All co-culture treatments were recorded superior to the respective monocultures and the uninoculated control.

The results of FW biodegradation using batch-biodigester trial indicated that the 1500 mL and 1000 mL inoculum size of HPB inoculant reached a plateau on the 4th day, with gross biodegradation percentage (GBP) of >85% as compared to control (66.4%).

The 1000 mL inoculum was sufficient to achieve the maximum GBP (>90%) of FW after an 8- day biodigestion in a FWB.