Purpose: This study investigate the survivability patterns and the capacity of Lactobacillus rhamnosus GG (LGG) for inhibition and biofilm control.
Methods: Powdered milk samples from Bodija market, Ibadan were assessed for the presence of Aspergillus species using standard methods. Two isolates from powdered milk sample and a laboratory stock culture (A. niger) of 104 or 106 CFU/ml concentrations of each were used for survivability and biofilm development studies over a 5-day period at refrigeration and room temperatures. Inhibition of Aspergillus growth and biofilm formation was tested with 104 and 108 CFU/ml of LGG. Aspergillus counts and biofilm mass were determined using standard methods and crystal violet binding assay, respectively. Data were analyzed using ANOVA (P<0.05).
Results: A. niger and A. flavus were isolated from powdered milk samples. Aspergillus growth was significantly higher in days 3 (8.14 log CFU/5g) and 5 (7.90 CFU/5g) than the day 1 of incubation (6.39 CFU/5g). A. niger produced lower fungal load than A. flavus. There was a significant difference in mean fungal load with different concentrations of LGG. Both Aspergillus species yielded the highest fungal load at day 3 of incubation. Similarly, both Aspergillus spp produced more fungal load at room temperature than at refrigeration. Biofilm production was significantly higher in day 3 (0.147) than in day 5 (0.106) and 1 of incubation (0.104). Biofilm production was higher at 104 CFU (0.119) than at 106 (0.118) CFU. There were significant differences in biofilm forming mass between species. Furthermore, a significant reduction in mean biofilm mass was observed in the presence of LGG
Significance: Aspergillus spp. in this study had biofilm forming abilities. LGG is useful in the control Aspergillus multiplication and biofilm development.