Comparison of biofilm formation by Desulfovibrio spp. using test tube and cover slip assay using 2-way ANOVA analysis. Desulfovibrio spp. was grown in lactate sulfate media for 72 h at 37°C and pH 7. OD was measured at 590 nm. Test tube assay showed significantly strong biofilm formation after 5 days compared to coverslip assay (p˂0.001). Error bars represent standard deviation (n=3) and * is significantly different.