Investment casting relies on a high-quality ceramic shell for successful production. However, shell-making suffers from a high rejection rate (around 35%) and consumes a significant portion of the total energy used in the process (nearly one-third). This inefficiency is often linked to issues with the ceramic slurry, particularly the growth of microorganisms within the mixture. This study investigates the impact of microbial presence on the quality and performance of ceramic slurry used in investment casting. The typical slurry composition involves a mixture of finely-ground (300-400 mesh) zircon flour (typically 75%) as the primary refractory material and hydrolysed ethyl silicate or colloidal silica (typically 25%) acting as a binder. Maintaining precise slurry properties, including viscosity, pH, and specific gravity, is very crucial for appropriate shell formation. However, microbial growth within the slurry can disrupt these properties, adversely affect factors including life of slurry and cold strength of the resulting mould. Present work provides better insight on presence as well as identification of various microorganisms in ceramic slurry used in investment casting process as well as secondary metabolites to control growth of those microorganisms observed in ceramic slurry. Various secondary metabolites have been tested to control the growth. It was observed that Enterococcus hirae has shown promising results to control overall growth of microorganism, and can further be explored for development of antibiotics for industrial purpose.