Biochemical and microbiological soil effects of a biostimulant based on Bacillus licheniformis-fermented sludge

Resumo

A fermentative process has been applied to carry out the conversion of sludge from slaughterhouse wastewater treatment into a biostimulant complex. The three biostimulant components are: a) The Bacillus licheniformis biomass, which is a plant growth promoter rhizobacteria (PGPR), and the organism in charge of the fermentative process, b) the enzymatic secretion of said microorganism, mainly peptidases and amidases (50%), involved in N metabolism, and glucanases (33.3%), involved in carbohydrate metabolism, and c) the hydrolyzed sludge organic matter, largely composed of peptides and free aminoacids. The biostimulant has been evaluated in soil at the biochemical and microbiological level. It induced a strong microbial stimulation of the soil, and produced the specific stimulation of PGPR soil bacteria, which was studied through a metabarcoding. Moreover, mainly when applying the soluble fraction of the biostimulant complex, it was found that the Bacillus licheniformis inoculum remains active in the environment at the end of the experiment.