Hierarchical diversity partitioning of microscopic epibiont community on intertidal molluscan shells and inert surfaces over three geographic regions in Japan.

Microscopic epibionts on molluscan shells are a component of the biodiversity of intertidal coastal areas. Because molluscan shells are discrete habitats for the epibiont community, and the molluscan basibionts belong to the local community, epibiont diversity can be evaluated hierarchically by basibiont categories including species. To evaluate the structure of epibiont diversity and effects of taxonomic resolution on the evaluation, epibionts on molluscan shells and inert surfaces were investigated at three geographically distant sites in Japan.

Antibacterial properties of nine pure metals: a laboratory study using Staphylococcus aureus and Escherichia coli.

Bacterial attachment and growth on material surfaces are considered to be the primary steps leading to the formation of biofilm. Biofilms in hospital and food processing settings can result in bacterial infection and food contamination, respectively. Prevention of bacterial attachment, therefore, is considered to be the best strategy for abating these menaces and therefore the development of antibacterial metals becomes important.

Laboratory studies on biomachining of copper using Staphylococcus sp.

The possibility of using bacteria to drill metallic surfaces has been demonstrated using Staphylococcus sp., a facultative anaerobic bacterium, isolated from corroded copper piping. The experiment involved exposure of copper coupons (25 mm x 15 mm x 3 mm) to a culture of Staphylococcus sp.

Laser damage to marine plankton and its application to checking biofouling and invasion by aquatic species: a laboratory study.

In this laboratory study, the ability of low-power pulsed laser irradiation to kill planktonic organisms in a flowing water system was examined, thus, to test the possibility of using this technique as a water treatment strategy to reduce biofouling growth in condenser tubes of power plants and to reduce bioinvasion via the ballast water of ships. Two flow rates (4.6 and 9.

The bactericidal effect of ultraviolet and visible light on Escherichia coli.

The bactericidal radiation dosages at specific wavelengths in the ultraviolet (UV)-visible spectrum are not well documented. Such information is important for the development of new monochromatic bactericidal devices to be operated at different wavelengths. In this study, radiation dosages required to cause mortality of an Escherichia coli strain, ATCC 25922, at various wavelengths between 250 and 532 nm in the UV and visible spectrum were determined.

Visible laser and UV-A radiation impact on a PNP degrading Moraxella strain and its rpoS mutant.

The role of stationary phase sigma factor gene (rpoS) in the stress response of Moraxella strain when exposed to radiation was determined by comparing the stress responses of the wild-type (WT) and its rpoS knockout (KO) mutant. The rpoS was turned on by starving the WT cultures for 24 h in minimal salt medium. Under non-starved condition, both WT and KO planktonic Moraxella cells showed an increase in mortality with the increase in duration of irradiation.

In vitro laser ablation of natural marine biofilms.

We studied the efficiency of pulsed low-power laser irradiation of 532 nm from an Nd:YAG (neodymium-doped yttrium-aluminum-garnet) laser to remove marine biofilm developed on titanium and glass coupons. Natural biofilms with thicknesses of 79.4 +/- 27.

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

We studied the laser ablation of laboratory-developed biofilm on titanium and glass surfaces. Specifically, Pseudoalteromonas carrageenovora, a marine biofilm forming bacterium was used to generate laboratory biofilm. Two fluences, 0.

Recolonization of laser-ablated bacterial biofilm.

The recolonization of laser-ablated bacterial monoculture biofilm was studied in the laboratory by using a flow-cytometer system. The marine biofilm-forming bacterium Pseudoalteromonas carrageenovora was used to develop biofilms on titanium coupons. Upon exposure to a low-power pulsed irradiation from an Nd:YAG laser, the coupons with biofilm were significantly reduced both in terms of total viable count (TVC) and area cover.

Microfouling studies on experimental test blocks of steel-making slag and concrete exposed to seawater off Chiba, Japan.

Microfouling studies with the emphasis on microalgae (Bacillariophyceae) were carried out on test blocks of steel-making slag in comparison with concrete. Two types of slag test blocks, with and without fly-ash as an additional source of silica, and concrete test blocks of size 75 x 26 x 26 mm were used to study microfouling build-up for a period of 30 d, with intermittent samplings after 1, 2, 3, 7, 14 and 21 d. The species composition, cell density, biomass and surface pH of the test pieces were determined, in addition to the hydrographic parameters of the water column.

Lethal and sub-lethal impacts of pulsed laser irradiations on the larvae of the fouling barnacle Balanus amphitrite.

Laboratory experiments were conducted to study the impact of laser irradiation on the larvae of the fouling barnacle Balanus amphitrite. Research pertaining to fouling invertebrate larvae-laser interaction is sparse and, hence, data on this aspect were thought significant in order to consider pulsed low power laser irradiations as a possible future antifouling tool. Lethal and sub-lethal impacts of four very low laser fluences, viz.

Laser impact on marine planktonic diatoms: an experimental study using a flow cytometry system.

A flow cytometry system was used to evaluate the impact of pulsed laser irradiations from an Nd:YAG laser on two marine coastal water diatoms, Chaetoceros gracilis and Skeletonema costatum. Three flow speeds, i.e.

Laser impact on bacterial ATP: insights into the mechanism of laser-bacteria interactions.

The mechanisms of laser action on bacteria are not adequately understood. Here, an attempt has been made to study the fluctuation in ATP (adenosine triphosphate) concentration following laser irradiation from a pulsed Nd:YAG laser on a marine biofilm-forming bacterium Pseudoalteromonas carrageenovora. A stationary phase bacterial suspension (density 10(7-8) ml-1) was exposed to pulsed laser irradiations at a fluence of 0.

Pulsed laser irradiation impact on two marine diatoms Skeletonema costatum and Chaetoceros gracilis.

The ability of pulsed laser irradiations to cause damage on the biofouling organisms is recently being investigated. If this technique is employed in industries such as power generation wherein a large quantity of water is being used for the cooling purpose, many organisms other than the targeted would get affected. In this study, we have investigated the damage caused by the pulsed laser irradiations from an Nd:YAG laser (fluence 0.

Laser impact assessment in a biofilm-forming bacterium Pseudoalteromonas carrageenovora using a flow cytometric system.

Impact by pulsed laser irradiations from an Nd:YAG laser on the marine biofilm-forming bacterium Pseudoalteromonas carrageenovora has been studied using a flow cytometric system. The biofilm-forming bacteria in the planktonic state have been irradiated while flowing, and the mortality and bacterial attachment have been determined by exposing TiN coupons in the system. Coupons suspended in the non-irradiated bacterial flow were treated as the control.

Inhibition of bacterial attachment by pulsed Nd:YAG laser irradiations: an in vitro study using marine biofilm-forming bacterium Pseudoalteromonas carrageenovora.

The effect of low mean power laser irradiations with short pulse duration from an Nd:YAG (neodymium-doped yttrium aluminium garnet) laser on a marine biofilm-forming bacterium, Pseudoalteromonas carrageenovora, was investigated in the laboratory. Laser-irradiated bacteria were tested for their ability to attach on nontoxic titanium nitride (TiN) coupons with nonirradiated bacteria as the reference. Two durations of irradiation were tested, 10 and 15 min.

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

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.