Bacterial growth in poly(vinyl alcohol) hydrogel with nutrients and indicator

Bacterial culture has traditionally been a widely used method for isolating and detecting bacteria, particularly in the food industry. However, the conventional culture method is now considered outdated, time-consuming, and labor-intensive. To overcome these limitations, a dried thin film medium known as Petrifilm has been developed for various bacterial culture applications. In this study, a poly(vinyl alcohol) (PVA) hydrogel was developed as an innovative approach for thin film bacterial culture. This hydrogel, incorporating bromothymol blue (BB) and tryptic soy broth (TSB), referred to as BBTH, was synthesized in different thicknesses using freeze-thaw techniques. Comprehensive hydrogel characterization was performed to determine the optimal hydrogel for bacterial culture. The suitability of BBTH for bacterial cultivation was validated using Escherichia coli ATCC25922 and Staphylococcus aureus ATCC25923, representing Gram-negative and Gram-positive bacteria, respectively. The results demonstrated the successful synthesis of BBTH hydrogel in five different thicknesses. Among these variants, 2-BBTH (thickness 0.50 ± 0.01 mm) exhibited the most favorable properties, including ideal thickness, high transparency, water absorption, clear representation of bacterial growth, and colony formation. Compared to the conventional method using tryptic soy agar (TSA), 2-BBTH yielded comparable results, with observable bacterial colonies at the same concentration. This study highlights the potential of BBTH as a promising alternative for developing innovative commercial bacterial culture platforms.