The Scientific World Journal

Research Article

Bactericidal Effects of 405 nm Light Exposure Demonstrated by Inactivation of Escherichia, Salmonella, Shigella, Listeria, and Mycobacterium Species in Liquid Suspensions and on Exposed Surfaces

Table 2

Inactivation of bacteria seeded onto agar surfaces upon exposure to high-intensity 405 nm light for different times. Agar plates (9 cm diameter) were exposed to an average irradiance of 71 mW cm^–2.

Dose

S. enterica (Log₁₀ CFU/plate ± SD)

S. sonnei (Log₁₀ CFU/plate ± SD)

E. coli 0157:H7 (Log₁₀ CFU/plate ± SD)

L. monocytogenes (Log₁₀ CFU/plate ± SD)

Exposure time (min)

(J cm²)

Non-light exposed

Light exposed

Log₁₀ reduction
(% reduction)

Non-light exposed

Light exposed

Log₁₀ reduction
(% reduction)

Non-light exposed

Light exposed

Log₁₀ reduction
(% reduction)

Non-light exposed

Light exposed

Log₁₀ reduction
(% reduction)

—

2.44 (±0.02)

2.37 (±0.03)

0.07* (15.3%)

2.38 (±0.03)

2.33 (±0.02)

0.05 (11.3%)

2.28 (±0.02)

1.82 (±0.12)

0.46* (64.4%)

2.32 (±0.02)

2.09 (±0.13)

0.23* (39.4%)

—

120

—

2.33 (±0.10)

1.65 (±0.30)

0.68* (76.4%)

180

2.33 (±0.01)

1.19 (±0.30)

1.14* (91.4%)

2.21 (±0.09)

0.93 (±0.40)

1.28* (93.3%)

2.27 (±0.03)

0.90 (±0.10)

1.37* (95.7%)

2.25 (±0.06)

0 (±0.00)

2.25* (100%)

270

2.28 (±0.02)

0 (±0.00)

2.28* (100%)

2.26 (±0.04)

0.16 (±0.30)

2.10* (99.3%)

2.18 (±0.02)

0 (±0.00)

2.18* (99.8%)

—

*Indicates where a light-exposed sample value was statistically significant from a non-exposed control value ( calculated at the 95% confidence interval).
SD: standard deviation of averaged results.