Ammonia release from hydrolysed animal and food waste by the hop endophyte, Pantoea agglomerans

The food industry and agriculture produce large amounts of waste that can be used in many upcycling applications. An interesting solution may be to return the necessary nutrients for plants to the soil and improve plant growth at the same time by using waste from animal production and food processing as a substrate for endophytic bacteria. Endophytic bacteria that naturally colonize plants can help plants absorb nutrients and may produce substances that promote plant growth. Animal waste (feathers, chicken or fish scraps) and spent brewer's yeast rich in protein were hydrolysed into a mixture of soluble peptides and amino acids. The hydrolysates were used for the release of ammonium ions by the bacterium Pantoea agglomerans DBM 3797, isolated from hops. The release of ammonium ions is a result of excess nitrogen over carbon during the growth of bacteria that use amino acids as a source of carbon and energy. Ammonium ions are a form of nitrogen that is very easily utilized by plants. High concentrations of ammonium ions in g/L were achieved with both acidic and alkaline chicken feather hydrolysates and in spent brewer's yeast autolysate, with the highest ammonium ions per unit of original material (41 mg/g) being released from the feather alkaline hydrolysate. It was also confirmed that differences in waste types and their processing have a significant effect on ammonia release, which is important for the development of a new biofertilizer. Proof of concept test on 3-week-old lettuce seedlings showed that addition to the soil of hydrolysate containing P. agglomerans significantly promoted the growth of the plant root system.