Standardizing Fungal Biomass via Optical Density for Reproducible Cell-Free Filtrate Formulation

Effective mycoherbicide development requires reproducible fungal biomass production and consistent recovery of bioactive metabolites.Optical density (OD600) measurement is a rapid, non-destructive technique that has been widely adopted as a surrogate indicator of microbial biomass in liquid culture systems.In the present investigation, a calibration curve between OD600 values and viable colony forming units (CFU/mL) was established for fungal isolates being utilized in cell-free culture filtrate (CFCF) based mycoherbicide formulation.Cultures were grown under standardized conditions, turbidity was recorded spectrophotometrically, and viable counts were determined through serial dilution and plating methods.The regression analysis revealed a strong linear correlation within the exponential growth range, approximating CFU/mL ≈ 2.0 × 10 -6 × OD.Harvesting cultures at OD thresholds of 0.75 to 1.0 ensured uniform biomass levels prior to metabolite extraction and significantly reduced batch-to-batch variability.Earlier studies on novel fungal bioherbicide developed also emphasized the importance of inoculum standardization for achieving consistent herbicidal efficacy.Although OD measurements cannot differentiate viable from nonviable cells and lose accuracy at higher values due to light scattering, their integration with periodic CFU validation provides a robust quality control framework.These findings position ODbased biomass monitoring as an essential methodological tool for scaling mycoherbicide production from laboratory to industrial levels.