The cellular and microbial response to light irradiation is a well-known phenomenon. In Escherichia coli, one of the physiological responses consists of observing an increased number of viable cells in irradiated cultures with respect to control cultures. This is due to increased proton motive force (PMF) that results from the excitement caused by light absorption on the iron atom on the Heme groups of cytochromes bd and bo and the copper atom on cytochrome bo. This increase in the number of viable cells is quantified by measuring the optical density (λ = 600 nm). According to this, irradiated cultures show a higher optical density than control cultures during the first two or three hours of bacterial growth. This paper presents experimental results for a novel tunable pulsed supercontinuum laser source at four peak wavelengths (570, 622, 633, and 733 nm). Our observations showed a coincidence in the observation of the photobiomodulation phenomenon for the novel characteristics of the laser source used. To explain this, a growth curve was constructed from the absorbance values of the irradiated and control cultures registered at every hour during a period of five hours.