Screening and Characterization of Microbial Consortia for Biodegradation of High-Salt and High-Oil Food Waste

In response to the low efficiency of traditional landfill and incineration methods for food waste, as well as the poor biodegradation rates caused by its high-salt and high-oil components, this study focused on screening microbial strains with tolerance to such extreme environments and the capacity to produce amylase, aiming to enhance biodegradation efficiency. Through systematic isolation, purification, gradient salt-oil tolerance screening, and characterization, highly efficient degrading strains were selectively isolated from food waste, and molecular biology techniques were employed for species identification. Additionally, a comprehensive evaluation was conducted on the degradation characteristics of each strain (including key indicators such as amylase activity, emulsification ability, and degradation rate) and the application performance of the composite microbial agent in simulated fermentation systems.The study successfully screened four highly efficient degrading strains: M1-1 (Kocuria marina, Kocuria genus), M3-2 (Raoultella ornithinolytica, Ornithinolytica genus), Y4-2 (Candida tropicalis, Tropicalis yeast), and Y4-4 (Trichosporonsp., Trichosporon genus). Experimental data revealed that their volatile solids (VS) degradation efficiency reached up to 9.2 times that of the control group. These strains not only demonstrated strong tolerance to high-salt (≤ 5%) and high-oil (≤ 5%) environments but also exhibited remarkable amylase production capacity (enzyme activity of 93.87 U/mL) and excellent emulsification performance (emulsification coefficient approaching 100% after 40 hours of cultivation). Furthermore, in simulated fermentation systems, the composite microbial agent formulated with a bacterial-to-fungal ratio of M:Y = 1:2 (i.e., bacteria:fungi = 1:2) demonstrated optimal performance—achieving a 26.8% reduction rate within 5 days and a significant decrease in the E4/E6 ratio, indicating substantial resource recovery potential.This study represents the first successful isolation and identification of a specific bacterial-fungal consortium capable of synergistically and efficiently degrading high-salt and high-oil components in food waste, with the optimal ratio (M:Y = 1:2) clearly defined. The constructed composite agent significantly enhanced degradation efficiency through synergistic microbial interactions, providing not only essential microbial resources and theoretical support for the industrial application of food waste bio-treatment technologies but also critical scientific foundations for advancing green and low-carbon treatment approaches. This research holds significant practical value and innovative importance.