This study demonstrates the susceptibility of a variety medically important bacteria to inactivation by 405-nm light from an array light-emitting diodes (LEDs), without application exogenous photosensitizer molecules. Selected bacterial pathogens, all commonly associated with hospital-acquired infections, were exposed LED array, and results show that both gram-positive gram-negative species successfully inactivated, general trend showing be more susceptible than bacteria. Detailed...

ABSTRACT The effects of high-intensity pulsed-light emissions high or low UV content on the survival predetermined populations Listeria monocytogenes , Escherichia coli Salmonella enteritidis Pseudomonas aeruginosa Bacillus cereus and Staphylococcus aureus were investigated. Bacterial cultures seeded separately surface tryptone soya-yeast extract agar reduced by up to 2 6 log 10 orders with 200 light pulses (pulse duration, ∼100 ns) content, respectively ( P < 0.001).

The lethality of high-intensity pulsed-light emissions from low and high ultraviolet (UV) light sources on predetermined microbial populations has been investigated. Prior to treatment, the bacterial enteropathogens Bacillus cereus, Escherichia coli, Salmonella enteritidis food-spoilage fungi Aspergillus niger Fusarium culmorum were seeded separately onto surface either tryptone soya yeast extract or malt agar plates. Prescribed population densities applied test media these samples exposed...

The distribution, abundance, and types of micro-organisms attached to littoral sublittoral sand grains have been described. Micro-organisms are present in colonies, ranging from 5 150 cells per colony. Many colonies consist one species. Some or surrounded by staining material, others on flat unstained surfaces. Colonies material often occur hollows. Large areas surface between the completely bare. Evidence suggests that abrasion may stop colonizing convex On sediment surface, bacteria,...

The bactericidal effect of 405 nm light was investigated on taxonomically diverse bacterial pathogens from the genera Salmonella, Shigella, Escherichia, Listeria, and Mycobacterium . High-intensity light, generated an array 405-nm light-emitting diodes (LEDs), used to inactivate bacteria in liquid suspension exposed surfaces. L. monocytogenes most readily inactivated suspension, whereas S. enterica resistant. In surface exposure tests, more susceptible than Gram-negative enteric when agar...

Light at wavelength 405 nm is an effective bactericide. Previous studies showed that exposing mammalian cells to light 36 J/cm2 (a bactericidal dose) had no significant effect on normal cell function, although higher doses (54 J/cm2), death became evident. This research demonstrates and bacterial toxicity induced by exposure accompanied reactive oxygen species production, as detected generation of fluorescence from 6-carboxy-2′,7′-dichlorodihydrofluorescein diacetate. As indicators the...

SUMMARY: The ability of Aspergillus niger conidia to produce conidiophores after germination in shaken culture at 30° was stimulated by the inclusion glutamate medium. Incubation 35° 41° increased swelling and also proportion which produced conidiophores. Although conidio-phore initiation temperatures between 41°, maturation poor optimum conidiation obtained incubation these followed 30°. Conidiophore formation from required a prior period spore metabolism did not occur until several hours...

The effects of high intensity light emissions, produced by a novel pulsed power energization technique (PPET), on the survival bacterial populations verocytotoxigenic Escherichia coli (serotype 0157:H7) and Listeria monocytogenes 4b) were investigated. Using this PPET approach, many megawatts (MW) peak electrical dissipated in source an extremely short time (about 1 microsecond). was subjected to electric field levels greater than could be achieved under conventional continuous operation,...

This study was conducted to investigate the bactericidal effects of visible light on methicillin-sensitive and methicillin-resistant Staphylococcus aureus (MRSA), subsequently identify wavelength sensitivity S. aureus, in order establish wavelengths inducing maximum inactivation. including MRSA strains, were shown be inactivated by exposure high-intensity light, and, more specifically, through a series studies using xenon broadband white-light source conjunction with selection optical...

Abstract Resistance of bacterial endospores to treatments, including biocides, heat and radiation is a persistent problem. This study investigates the susceptibility Bacillus Clostridium 405 nm visible light, wavelengths which have been shown induce inactivation vegetative cells. Suspensions B. cereus were exposed high‐intensity light generated from light‐emitting diode array results demonstrate induction sporicidal effect. Up 4‐log 10 CFU mL −1 reduction in spore population was achieved...

The antimicrobial properties of light is an area increasing interest. This study investigates the sensitivity significant foodborne pathogen Listeria monocytogenes to selected wavelengths visible light. Results demonstrate that exposure wavelength region 400-450 nm, at sufficiently high dose levels (750 J cm(-2)), induced complete inactivation a 5 log(10) population. Exposure longer than 450 nm did not cause inactivation. Analysis 10 bandwidths between 400 and confirmed 405(± 5) be most...

Bacterial inactivation by 405 nm light is accredited to the photoexcitation of intracellular porphyrin molecules resulting in energy transfer and generation reactive oxygen species that impart cellular oxidative damage. The specific mechanism damage, however, not fully understood. Previous work has suggested destruction nucleic acids may be responsible for inactivation; microscopic imaging membrane damage as a major constituent inactivation. This study investigates integrity Escherichia coli...

Antimicrobial violet-blue light in the region of 405 nm is emerging as an alternative technology for hospital decontamination and clinical treatment. The mechanism action excitation endogenous porphyrins within exposed microorganisms, resulting ROS generation, oxidative damage cell death. Although resistance to not thought likely, little evidence has been published support this. This study was designed establish if there potential tolerance development, using nosocomial pathogen...

ABSTRACT Forty-seven strains representing 14 different Bacillus species isolated from clinical and food samples were grown in reconstituted infant milk formulae (IMF) subsequently assessed for adherence to, invasion of, cytotoxicity toward HEp-2 Caco-2 cells. Cell-free supernatant fluids 38 (81%) shown to be cytotoxic, 43 (91%) adhered the test cell lines, 23 (49%) demonstrated various levels of invasion. Of 21 cereus examined, 5 (24%) invasive. A larger percentage clinically derived (20%)...

Attachment of bacteria to surfaces and subsequent biofilm formation remains a major cause cross-contamination capable inducing both food-related illness nosocomial infections. Resistance many current disinfection technologies means facilitating their removal is often difficult. The aim this study was investigate the efficacy 405 nm light for inactivation bacterial attached as biofilms glass acrylic. Escherichia coli (10(3)-10(8) CFU mL(-1)) were generated on acrylic exposed increasing times...