Impact of pulsed Nd:YAG laser on the marine biofilm-forming bacteria Pseudoalteromonas carrageenovora: significance of physiological status

Abstract

The impact of pulsed Nd:YAG (neodymium-doped yttrium/aluminium garnet) laser irradiation on the marine biofilm-forming bacteria Pseudoalteromonas carrageenovora during two growth stages (log phase and stationary phase) and under two stresses (reduced temperature and nutrient limitation) was investigated. Bacteria were exposed to a laser fluence of 0.1 J x cm(-2) for 5, 10, and 15 min with a peak power of 20 MW x cm(-2), a pulse width of 5 ns, and an average power of 1 W x cm(-2) with a repetition rate of 10 Hz. The mortality of bacteria immediately after the irradiation as well as after a set period of time was determined. Mortality was higher among log-phase bacteria (72%) than bacteria in the stationary phase (51%) and those grown under nutrient limitation (51%). Bacteria grown at reduced temperature had a mortality of 49%. However, the differences in cell density of log-phase, stationary-phase, nutrient-limited, and low-temperature irradiated samples compared with controls after 5 h of incubation were 96, 93, 94, and 86%, respectively. The mortality values suggest that the same laser fluence has different degrees of effectiveness, depending on the physiological state of the bacteria.

In vitro laser ablation of laboratory developed biofilms using an Nd:YAG laser of 532 nm wavelength

“…This bacterium is eurithermal and grows at a very high speed at room temperature. Details regarding the growth pattern of this bacterium are given in an earlier report (Nandakumar et al, 2002c). For the present experiments, 6-h-old biofilm was used.…”

“…For each fluence, three durations were tested-30 s, 5 min, and 10 min, respectively. These durations were selected based upon our earlier studies on this bacterium (Nandakumar et al, 2002c). During the irradiation of a coupon, another coupon kept in a separate container similar to the irradiation chamber for the same duration served as the control.…”

Biofouling and Its Prevention: A Comprehensive Overview.

“…Other recent developments in non-toxic methods Some of the other non-toxic fouling control methods under study and investigation include electrochemical methods Nakayama et al, 1998) , production of material with antibacterial properties (Sreekumari et al, 2002 and2003), and laser irradiation (Nandakumar et al, 2002a(Nandakumar et al, , 2002b(Nandakumar et al, and 2002c. In the electrochemical methods, the surface to be protected is made to be an anode for the electrolysis of seawater.…”

Silver Containing Stainless Steel as a New Outlook to Abate Bacterial Adhesion and Microbiologically Influenced Corrosion

“…[9][10][11] Stainless steel is the most widely used material in industries. Stainless steels, inherently do not posses antibacterial property.…”