<![CDATA[Biofertilizer formulations based on spore-forming Bacillus support integrated plant nutrient management. The objective of this laboratory experiment was to compare cell and spore counts of four Bacillus species and their consortia across different growth media, as well as the acidity and electrical conductivity of the media. The assay tested two molasses-based liquid media for cell proliferation and sporulation of B. safensis B1, B. subtilis D2, B. altitudinis B14, and Bacillus sp. E2, and their consortium. Batch cultures were performed using 50 mL of tryptic soy broth in a 250-mL Erlenmeyer flask at room temperature for 9 days with agitation at 115 rpm. Cell proliferation and sporulation were influenced differently by medium composition and varied across all strains and the consortium. Formula B, composed of molasses 2%, peptone 10 g, and beef extract 2 g, produced the highest cell populations, followed by Formula C and Formula A. The highest final spore population was found in Formula A, which contained molasses 2%, peptone 10 g, and beef extract 3 g, particularly for Bacillus sp. E2, B. altitudinis B14, and the consortium. Formula C, a specific medium for Bacillus, supported cell proliferation but poor sporulation. The highest acidity (pH) and electrical conductivity (EC) of the liquid inoculant were found in Formula C. This study indicated that sporulation capacity depended on the medium composition and the Bacillus strain, whereas changes in pH and EC were determined solely by the formula. All liquid inoculants had bacterial populations and acidity levels within Indonesian regulatory limits. Keywords: Acidity, Electrical conductivity, Molasses, Spore, Vegetative cell]]>
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