Measurement of UV radiation using suspensions of microorganisms

Sommer, Regina; Cabaj, Alexander; Sandu, Tudor; Lhotsky, M.

doi:10.1016/s1011-1344(99)00113-x

Cited by 28 publications

(13 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The inactivation rate constant K (square centimeters per millijoule) for the bacteria irradiated in the present studies varied from 0.065 for B. subtilis to 1.37 for Vibrio cholera (33). The rate constant for E. coli found in our studies varies from 0.63 to 0.52, which is also in very good agreement with the literature value of 0.54 (30,34). It might be interesting to note that the sensitivity to monochromatic and polychromatic UV radiation in the same narrow wavelength region and same dose was found to be very similar when applied with the same UV flux.…”

Section: Resultssupporting

confidence: 91%

A tryptophan synchronous and normal fluorescence study on bacteria inactivation mechanism

Dhankhar

Chen

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

The UV photodissociation kinetics of tryptophan amino acid, Trp, attached to the membrane of bacteria, Escherichia coli and Bacillus subtilis, have been studied by means of normal and synchronous fluorescence. Our experimental data suggest that the fluorescence intensity of Trp increases during the first minute of irradiation with 250 nm to ∼ 280 nm, 7 mW/cm2 UV light, and subsequently decreases with continuous irradiation. During this short, less than a minute, period of time, 70% of the 107 cell per milliliter bacteria are inactivated. This increase in fluorescence intensity is not observed when tryptophan is in the free state, namely, not attached to a protein, but dissolved in water or saline solution. This increase in fluorescence is attributed to the additional fluorescence of tryptophan molecules formed by protein unfolding, the breakage of the bond that attaches Trp to the bacterial protein membrane, or possibly caused by the irradiation of 2 types of tryptophan residues that photolyze with different quantum yields.

show abstract

Section: Resultssupporting

confidence: 91%

A tryptophan synchronous and normal fluorescence study on bacteria inactivation mechanism

Dhankhar

Chen

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…Biodosimetric measurements depend on the survival function of the microorganisms and on the shape of the fluence distribution in the UV reactor, as a wide distribution will result in reduction equivalent fluence (REF) measurements that depend on the microorganism tested (Sommer et al 1999). MS2 is typically used as a challenge organism due to its first order kinetics, while the tailing and even the shoulder complicates the physical explanation of the REF phenomenon.…”

Section: Tailing Modelsmentioning

confidence: 99%

Impact of Particles on Uv Disinfection of Water and Wastewater Effluents: A Review

Mamane¹

2008

Reviews in Chemical Engineering

View full text Add to dashboard Cite

Particles in water sources may be classified in various groups such as living vs. non-living, nano vs. sub-micron to micron sized and mineral vs. organic. Living particles for example comprise of bacteria, viruses, protozoa and algae while non-living particles include mineral particles, organic particles, cell debris and macromolecules. Particles in water sources may be dispersed as single entities or associated with multiple particles in floes or aggregates. Particles may be further characterized by their chemical nature, size distribution, density, absorbance, scattering and typical gross measurements such as turbidity and suspended solids. Although ultraviolet (UV) irradiation is principally accepted as a primary disinfection technology for use in water and wastewater effluent, still research is needed to understand the extent to which particles in water may hinder the UV treatment efficacy by interacting with microbial pathogens. Both of the phenomena: (1) particles physically associated with microorganisms in a clump or aggregate and (2) particles not physically associated with microorganisms however interact by shielding, absorbing, scattering or blocking UV light, are integrated in the term "particle-microbe interactions". This review covers the impact of the interaction between microorganisms (mainly bacteria) which are the target for UV disinfection and particles in water and wastewater effluents on the efficacy of UV disinfection.

show abstract

“…Large shoulders of repair proficient Escherichia coli strains exposed to near u.v. were because of the fluence‐dependent repair process, where repair decreases as fluence increases (Webb and Brown 1976), whereas repair deficient spores exhibit inactivation kinetics without shoulder (Tyrrell 1978; Munakata 1981; Sommer et al. 1999).…”

Section: Fluence‐based Inactivation Kineticsmentioning

confidence: 99%

Relationship between physiochemical properties, aggregation and u.v. inactivation of isolated indigenous spores in water

Mamane

Linden

2005

J Appl Microbiol

View full text Add to dashboard Cite

Aims: The objective of the study was to compare ultraviolet (u.v.) inactivation kinetics of indigenous aerobic spores in surface water with their laboratory-cultured spore isolates and to investigate the relationship between physicochemical characteristics and u.v. inactivation kinetics of spore isolates. Methods and Results: Lake water samples were analysed for the presence of indigenous aerobic spores. Different bacterial isolates from the heterogeneous indigenous population were genetically characterized, resporulated and examined for hydrophobicity, surface charge, particle size distribution and survival at different u.v. 254 nm fluence levels. Cultured isolated spores exhibited a three-stage inactivation curve consisting of shoulder, first order and tailing regions whereas indigenous spores exhibited only one stage of linear kinetics. Hydrophobicity of the Bacillus spore isolates was inversely related to the extent of u.v. inactivation before tailing occurred. Conclusions: Tailing in the u.v. inactivation curves results from aggregation of a portion of the spore population because of hydrophobic interactions, supporting the link between aggregation of spores, hydrophobicity and u.v. inactivation. Significance and Impact of the Study: Evidence of the link between spore physicochemical parameters and u.v. disinfection performance furthers the understanding of factors that affect inactivation of microbes in natural waters supplied to drinking water treatment plants.

show abstract

Measurement of UV radiation using suspensions of microorganisms

Cited by 28 publications

References 13 publications

A tryptophan synchronous and normal fluorescence study on bacteria inactivation mechanism

A tryptophan synchronous and normal fluorescence study on bacteria inactivation mechanism

Impact of Particles on Uv Disinfection of Water and Wastewater Effluents: A Review

Relationship between physiochemical properties, aggregation and u.v. inactivation of isolated indigenous spores in water

Contact Info

Product

Resources

About