Endophytic microbial strains as biocatalysts isolated from fresh plant samples, compositions, and methods of use thereof to enhance the growth and/or yield of a plant in the presence of reduced synthetic nitrogen fertilizers are provided. Endophytic microbial strains serve as biocatalysts to solubilize organic (proteinaceous) nitrogen otherwise unavailable to plants for their nutritional needs. Thus defined, biocatalysts will serve to replace synthetic nitrogen fertilizers. Also provided are materials and methods for inoculating plants with these biocatalysts at carefully selected inoculum densities to reliably reduce the amount of nitrogen fertilizer by 50% thus accomplishing optimal yields in technically and cost-effective manner.