Inoculation of lactic acid bacterium accelerates organic matter degradation during composting

• Pediococcus acidilactici TM14 was inoculated into the compost raw material.
• Without inoculation, acetic acid, which inhibits the microorganisms, accumulated.
• TM14 enhanced the growth of fungi having the ability to degrade organic acids.
• The fungi modified the environment and facilitated the growth of thermophile.
• Inoculation with TM14 accelerated composting via a new mechanism.

In this study, the impact of microbial inoculation upon indigenous microorganisms leading to the acceleration of food waste composting was investigated. The lactic acid bacterium Pediococcus acidilactici TM14 was inoculated into compost raw material composed of rabbit food with the addition of organic acids that simulate food waste. The strain TM14 produced a high concentration of lactic acid in the early stages of composting, whereas composting without inoculation of TM14 accumulated high levels of acetic acid, up to 22 mg g−1 dry solid of compost, which is detrimental to indigenous microorganisms. The growth of TM14 enhanced the proliferation of fungi having the ability to degrade organic acids, and thus the organic acids contained in the compost material were completely decomposed. Levels of TM14 and the fungi diminished immediately after the increase in composting temperature. However, the fungi modified the environmental conditions allowing for the activity of thermophilic bacteria, which play important roles in composting. In consequence, organic matter degradation in the composting was accelerated.