Inactivation by Pulsed Light of Bacillus subtilis Spores with Impaired Protection Factors

The resistance to pulsed light (PL) of spores of Bacillus subtilis strain 168 and of strains with mutations increasing sensitivity to UV‐C or affecting spore structure was evaluated and compared to resistance to continuous UV‐C and moist heat, in order to reveal original mechanisms of inactivation by PL. Spores of B. subtilis strain 168 (1A1) and eight mutant strains (sspA, sspB, sspAB, cotA, gerE, cotE, uvrA and recA) were exposed to PL (up to 1.77 J cm^?2), continuous UV‐C (up to 147 mJ cm^?2) and moist heat at 90°C. Spores of the strains lacking proteins linked to coat formation or structure (cotA, gerE and cotE) were markedly more sensitive to PL than 1A1, while their sensitivity to continuous UV‐C or to moist heat was similar to the one of strain 1A1. Coat proteins had a major contribution to the resistance of B. subtilis spores to PL irradiation characterized by short‐time and high‐energy pulses of white light in the wavelengths 200–1100 nm. In contrast the role of coat proteins to UV‐C or to moist heat resistance was marginal or null.     

Role of Ozone in UV‐C Disinfection,Demonstrated by Comparison between Wild‐Type and Mutant Conidia of Aspergillus niger

This study aimed to investigate the tolerance of a melanized wild‐type strain of Aspergillus niger (CON1) and its light‐colored mutant (MUT1) to UV–C light and the concomitantly generated ozone. Treatments were segregated into four groups based on whether UV irradiation was used and the presence or absence of ozone: (?UV, ?O₃), (?UV, +O₃), (+UV, ?O₃) and (+UV, +O₃). The survival of CON1 and MUT1 conidia under +UV decreased as the exposure time increased, with CON1 showing greater resistance to UV irradiation than MUT1. Ozone induced CON1 conidium inactivation only under conditions of UV radiation exposure. While, the inactivation effect of ozone on MUT1 was always detectable regardless of the presence of UV irradiation. Furthermore, the CON1 conidial suspension showed lower UV light transmission than MUT1 when examined at the same concentration. Compared with the pigment in MUT1, the melanin in CON1 exhibited more potent radical‐scavenging activity and stronger UV absorbance. These results suggested that melanin protected A. niger against UV disinfection via UV screening and free radical scavenging. The process by which UV–C disinfection induces a continual decrease in conidial survival suggests that UV irradiation and ozone exert a synergistic fungicidal effect on A. niger prior to reaching a plateau.     

Conidial pigmentation is important to tolerance against solar-simulated radiation in the entomopathogenic fungus Metarhizium anisopliae

The importance of conidial pigmentation to solar UV radiation tolerance in the entomopathogenic fungus Metarhizium anisopliae var. anisopliae, was estimated by comparing the effects of exposure to simulated solar UV radiation on the wild-type parent strain U.S. Department of Agriculture (USDA)-Agricultural Research Service (ARS) Collection of Entomopathogenic Fungal Cultures (ARSEF) 23, which has dark green conidia, and three groups of color mutants with yellow, purple and white conidia. The comparisons included inactivation levels and the kinetics of germination of conidia exposed or not exposed to simulated solar UV radiation. In addition to significantly inactivating the conidia of different mutants, exposure to radiation delayed for several hours the germination of surviving conidia of the wild type and all mutants. In general, mutants with white conidia were more sensitive to simulated solar UV radiation than mutants with purple conidia, which were more sensitive than mutants with yellow conidia, which in turn were more sensitive than the green wild strain. A significant variation in tolerance to simulated solar radiation was observed among mutants within each color group, particularly among mutants with yellow conidia. Revertants with green conidia, DWR 179 and DWR 176, were obtained from the very sensitive UV mutants DWR 148 (yellow conidia) and DWR 149 (purple conidia), respectively. These revertants had levels of tolerance to simulated solar UV radiation similar to those of the wild-type ARSEF 23. This observation is strong evidence of the importance of green conidial pigmentation for tolerance to simulated solar UV radiation, a factor that could be manipulated to produce M. anisopliae strains with more tolerance to solar UV radiation.     

Mutagenesis and analysis of mold Aspergillus niger for extracellular glucose oxidase production using sugarcane molasses

Aspergillus niger ORS-4.410, a mutant of A. niger ORS-4, was generated by repeated ultraviolet (UV) irradiation. Analysis of the UV treatment dose on wild-type (WT) A. niger ORS-4, conidial survival, and frequency of mutation showed that the maximum frequency of positive mutants (25.5%) was obtained with a 57% conidial survival rate after the second stage of UV irradiation. The level of glucose oxidase (GOX) production from mutant A. niger ORS-4.410 thus obtained was 149% higher than that for WT strain A. niger ORS-4 under liquid culture conditions using hexacyanoferrate (HCF)-treated sugarcane molasses (TM) as a cheaper carbohydrate source. When subcultured monthly for 24 mo, the mutant strain had consistent levels of GOX production (2.62±0.51 U/mL). Mutant A. niger ORS-4.410 was markedly different from the parent strain morphologically and was found to grow abundantly on sugarcane molasses. The mutant strain showed 3.43-fold increases in GOX levels (2.62±0.51 U/mL) using HCF-TM compared with the crude form of cane molasses (0.762±0.158 U/mL). The results reported herein were obtained while the author was working at the Department of Biotechnology, Indian Institute of Technology, Roorkee-247667, India.     

Effects of Suplementary Ultraviolet‐B Irradiance on Maize Yield and Qualities: A Field Experiment¶

Stratospheric ozone depletion has caused an increase in the amount of ultraviolet‐B (UV‐B) radiation reaching the earth's surface. Numerous investigations have demonstrated that the effect of UV‐B enhancements on plants includes reduction in grain yield, alteration in species competition, susceptibility to disease and changes in plant structure and pigmentation. Many experiments examining UV‐B radiation effects on plants have been conducted in growth chambers or greenhouses. It has been questioned whether the effect of UV‐B radiation on plants can be extrapolated to field responses from indoor studies because of the unnaturally high ratios of UV‐B/ ultraviolet‐A radiation (320–400 nm) and UV‐B/photosynthetically active radiation (PAR) in many indoor studies. Field studies on UV‐B radiation effect on plants have been recommended to use the UV and PAR irradiance provided by natural light. This study reports the growth and yield responses of a maize crop exposed to enhanced UV‐B radiation and the UV‐B effects on aize seed qualities under field conditions. Enhanced UV‐B radiation caused a significant reduction in the dry matter accumulation and the maize yield in turn was affected. With increased UV‐B radiation the flavonoid accumulation in maize leaves increased and the contents of chlorophyll a, b and (a+b) of maize leaves were reduced. The levels of protein, sugar and starch of maize seed decreased with enhanced UV‐B radiation, whereas the level of lysine increased with enhanced UV‐B radiation.     

Preparation,Structural Characterization,and Antifungal Activities of Complexes of Group 12 Metals with 2‐Acetylpyridine‐ and 2‐Acetylpyridine‐N‐oxide‐4N‐phenylthiosemicarbazones

Reaction of group 12 metal dihalides in ethanolic media with 2‐acetylpyridine ⁴N‐phenylthiosemicarbazone ( H4PL ) and 2‐acetylpyridine‐N‐oxide ⁴N‐phenylthiosemicarbazone ( H4PLO ) afforded the compounds [M(H4PL)X₂] (X = Cl, Br, M = Zn, Cd, Hg; X = I, M = Zn, Cd) ( 1–8 ), [Hg(4PL)I]₂ ( 9 ) and [M(H4PLO)X₂] (X = Cl, Br, I, M = Zn, Cd, Hg) ( 10–18 ). H4PL , H4PLO and their complexes were characterized by elemental analysis and by IR and ¹H and ¹³C NMR spectroscopy (and the cadmium complexes by ¹¹³Cd NMR spectroscopy), and H4PL , H4PLO , ( 5 · DMSO) and ( 9 ) were additionally studied by X‐ray diffraction. H4PL is N,N,S‐tridentate in all its complexes, including 9 , in which it is deprotonated, and H4PLO is in all cases O,N,S‐tridentate. In all the complexes, the metal atoms are pentacoordinate and the coordination polyhedra are redistorted tetragonal pyramids. In assays of antifungal activity against Aspergillus niger and Paecilomyces variotii, the only compound to show any activity was [Hg(H4PLO)I₂] ( 18 ).     

Two Novel Lanthanide Metal‐Organic Frameworks Constructed by Tetracarboxylate Ligands: Synthesis,Structures; and Luminescent Properties

Two new isostructural lanthanide metal‐organic frameworks were synthesized using lanthanide oxides and 3,3,4,4‐benzophenonetetracarboxylic acid (H₄BPTC), namely, [Ln(BPTC)(H₂O)_2.5] [Ln = Eu ( 1 ), Gd ( 2 )] under hydrothermal conditions. 1 and 2 revealed porous three‐dimensional structures, possessing a binodal 4, 8‐connected flu network defined by dinuclear building units. 1 and 2 were characterized by powder X‐ray diffraction (PXRD), thermogravimetric analysis (TG), infrared radiation (IR), and photoluminescence (PL) spectra. Furthermore, 1 exhibits red‐light emission under UV light irradiation and the sharp light can be easily observed by naked eyes.     

The Effects of Ambient Solar UV Radiation on Alkaloid Production by Erythroxylum novogranatense var. novogranatense†

Truxillines are alkaloids produced by Erythroxylum species and are thought to be derived from the UV‐driven dimerization of cinnamoylcocaines. This study was conducted to determine the effects of ambient UV radiation on the production of truxillines in Erythroxylum novogranatense var. novogranatense. Field plants were grown under shelters covered with plastic filters that were transparent to UV radiation, filtered UV‐B, or both filtered UV‐B and UV‐A radiation. The treatments had no significant effect on plant biomass or specific leaf weight. Absorption values in the UV‐C and UV‐A region of acidified‐methanol leaf extracts were higher for plants exposed to UV radiation compared to the no UV radiation treatment. There was a trend in decreasing levels of trans‐cinnamoylcocaine and a statistically significant decrease in levels of cis‐cinnamoylcocaine in the leaves of plants exposed to UV radiation compared to the no UV radiation treatment. Truxilline levels increased in leaves from plants exposed to UV radiation compared to the no UV radiation treatment. Most significantly, the ratio of truxillines to total cinnamoylcocaines in the leaves was affected by UV, increasing with increased UV exposure. The results support the hypothesis that UV radiation is involved in the formation of truxillines from cinnamoylcocaines.     

Preparation of a new polymer containing photoluminescent pyrazoline unit in the main chain

A novel photoluminescent polymer (PPyne) containing a 2‐pyrazoline unit in the molecular main chain was prepared (for the first time) by polycondensation between a 2‐pyrazoline monomer [an adduct of 2,6‐bis(4‐bromobenzylidene)cyclohexanone with phenylhydrazine] and 2,5‐dihexyloxy‐p‐phenylene diboric ester in the presence of Pd(PPh₃)₄. PPyne had a number‐average molecular weight of 7800 and a polydispersity index of 1.99 and showed good solubility in common organic solvents. In toluene PPyne exhibited an intrinsic viscosity [η] of 0.42 dL g^?1 at 30 °C. The polymer was photoluminescent (PL) in both the chloroform solution and the solid state; the quantum yield of PL in the solution was 40%. In the two states, PPyne gave the same ultraviolet–visible (UV–vis) peak at 368 nm and the same PL peak at 512 nm. DSC traces indicated that PPyne had a melting temperature of 168 °C, and thermogravimetric analysis revealed that the polymer had good thermal stability with a 5 wt % loss temperature of 376 °C under N₂. Electrochemical oxidation of PPyne started at about 0.5 V versus Ag/AgNO₃ and gave a peak at 0.98 V versus Ag/AgNO₃ with a color change of the film from yellow to black green. The color change was followed by UV–vis spectroscopy. The corresponding reduction peak appeared at 0.80 V versus Ag/AgNO₃. Treatment of PPyne with HCl led to dehydrogenating transformation of the polymer to a new cross‐conjugated polymer. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2686–2697, 2004     

Increased Antioxidant Activity and Changes in Phenolic Profile of Kalanchoe pinnata (Lamarck) Persoon (Crassulaceae) Specimens Grown Under Supplemental Blue Light

Antioxidant compounds protect plants against oxidative stress caused by environmental conditions. Different light qualities, such as UV‐A radiation and blue light, have shown positive effects on the production of phenols in plants. Kalanchoe pinnata (Lamarck) Persoon (Crassulaceae) is used for treating wounds and inflammations. Some of these beneficial effects are attributed to the antioxidant activity of plant components. We investigated the effects of blue light and UV‐A radiation supplementation on the total phenol content, antioxidant activity and chromatographic profile of aqueous extracts from leaves of K. pinnata. Monoclonal plants were grown under white light, white plus blue light and white plus UV‐A radiation. Supplemental blue light improved the antioxidant activity and changed the phenolic profile of the extracts. Analysis by HPLC of supplemental blue‐light plant extracts revealed a higher proportion of the major flavonoid quercetin 3‐O‐α‐l ‐arabinopyranosyl (1→2) α‐l ‐rhamnopyranoside, as well as the presence of a wide variety of other phenolic substances. These findings may explain the higher antioxidant activity observed for this extract. Blue light is proposed as a supplemental light source in the cultivation of K. pinnata, to improve its antioxidant activity.     

Coloring–decoloring behavior of fluoroalkyl end‐capped 2‐acrylamido‐2‐methylpropanesulfonic acid oligomer/acetone composite in methanol

A reddish‐brown fluoroalkyl end‐capped 2‐acrylamido‐2‐methylpropanesulfonic acid (AMPS) oligomer/acetone composite was prepared by heating the white oligomer powder with acetone at 80 °C for 3 h. The color was not observed in the corresponding non‐fluorinated AMPS oligomer/acetone composite, which was prepared under similar conditions. The coloring was probably caused by the formation of acetone polyaldol condensation products in the fluorinated oligomeric gel network cores. The colored R_F‐(AMPS)_n‐R_F/acetone composite powders were stable and did not exhibit any color change after 2 years in natural light at room temperature. The colored composite powders dissolved in methanol to give a reddish‐brown solution at room temperature. However, the retro‐polyaldol condensation decolored the solution after 1 day at room temperature. This is the first example of the retro‐aldol polycondensation of acetone under mild conditions. The decoloration increased by between 38‐ and 70‐fold under UV irradiation, compared with that in dark conditions. The coloring–decoloring behavior was consistent and repeatable; therefore our fluorinated oligomer/acetone composites are promising candidates for new fluorinated coloring materials. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2555–2564     

Development of sensitivity-improved fluorescence-linked immunosorbent assay using a fluorescent single-domain antibody against the bioactive naphthoquinone, plumbagin

A fluorescent single-domain antibody (fluobody), a fusion protein of a green fluorescent protein extracted from Aequorea coerulescens (AcGFP), a mutant that has been codon-optimized for mammalian expression, and a single-chain variable fragment antibody (scFv), against plumbagin (5-hydroxy-2-methyl-1,4-naphthoquinone; PL) was successfully constructed and expressed in Escherichia coli. The expressed fluobody was purified, refolded, and characterized to develop a speedy, simple, and sensitive fluorescence-linked immunosorbent assay (FLISA) for the determination of PL. In this study, two kinds of fluobody containing PL-scFv at the N-terminus of AcGFP (N fluobody) or the C-terminus of AcGFP (C fluobody) were constructed with flexible amino acid linker (Gly₄Ser)₂ between PL-scFv and AcGFP for comparative purposes. Characterization of the fluobodies revealed that the C fluobody has better properties as a probe for FLISA than the N fluobody because the fluorescence intensity of C fluobody was 18-fold higher than that of N fluobody. Moreover, C fluobody exhibited a fourfold-higher binding affinity than the N fluobody. More interestingly, the limit of detection for PL measurement in FLISA (24 ng mL⁻¹) was improved to eightfold higher than that in conventional ELISA (0.2 μg mL⁻¹), indicating that a sensitive immunoassay could be developed by using fluobody instead of monoclonal antibody or scFv.     

Photolysis and photocatalysis of ibuprofen in aqueous medium: characterization of by‐products via liquid chromatography coupled to high‐resolution mass spectrometry and assessment of their toxicities against Artemia Salina

The degradation of the pharmaceutical compound ibuprofen (IBP) in aqueous solution induced by direct photolysis (UV‐A and UV‐C radiation) and photocatalysis (TiO₂/UV‐A and TiO₂/UV‐C systems) was evaluated. Initially, we observed that whereas photocatalysis (both systems) and direct photolysis with UV‐C radiation were able to cause an almost complete removal of IBP, the mineralization rates achieved for all the photodegradation processes were much smaller (the highest value being obtained for the TiO₂/UV‐C system: 37.7%), even after an exposure time as long as 120 min. Chemical structures for the by‐products formed under these oxidative conditions (11 of them were detected) were proposed based on the data from liquid chromatography coupled to high‐resolution mass spectrometry (LC‐HRMS) analyses. Taking into account these results, an unprecedented route for the photodegradation of IBP could thus be proposed. Moreover, a fortunate result was achieved herein: tests against Artemia salina showed that the degradation products had no higher ecotoxicities than IBP, which possibly indicates that the photocatalytic (TiO₂/UV‐A and TiO₂/UV‐C systems) and photolytic (UV‐C radiation) processes can be conveniently employed to deplete IBP in aqueous media. Copyright © 2014 John Wiley & Sons, Ltd.     

Effects of Enhanced UV‐B Radiation on Biochemical Traits in Postharvest Flowers of Medicinal Chrysanthemum

This article reported UV‐B radiation effects on biochemical traits in postharvest flowers of chrysanthemum. The experiment included six levels of UV‐B radiation (UV0, 0 μW cm^?2; UV50, 50 μW cm^?2; UV200, 200 μW cm^?2; UV400, 400 μW cm^?2; UV600, 600 μW cm^?2 and UV800, 800 μW cm^?2). Enhanced UV‐B radiation significantly increased hydrogen peroxide content (except for UV50), but did not evidently affect malondialdehyde content in flowers. Chlorophyll b and total chlorophyll content were significantly increased by UV600 and UV800. UV400 and UV600 significantly increased anthocyanins, carotenoids and UV‐B absorbing compounds content, and the activities of phenylalanine ammonia lyase (PAL) and cinnamic acid‐4‐hydroxylase (C4H) over the control. 4‐coumarate CoA ligase (4CL) activity was significantly decreased by enhanced UV‐B radiation (except for UV50). The relationships between UV‐B radiation intensities and the activities of secondary metabolism enzymes were best described by a second‐order polynomial. The R² values for UV‐B radiation intensities and the activities of PAL, C4H and 4CL were 0.8361, 0.5437 and 0.8025, respectively. The results indicated that enhanced UV‐B radiation could promote secondary metabolism processes in postharvest flowers, which might be beneficial for the accumulation of medically active ingredients in medicinal plants. The optimal UV‐B radiation intensities in the study were between UV400‐UV600.     

GaN and GaxIn1−xN Nanoparticles with Tunable Indium Content: Synthesis and Characterization

Semiconducting GaN and Ga_xIn_1?xN nanoparticles (4–10 nm in diameter, depending on the metal ratio) with tunable indium content are prepared through a chemical synthesis (the urea‐glass route). The bandgap of the ternary system depends on its composition, and therefore, the color of the final material can be turned from bright yellow (the color of pure GaN) to blue (the color of pure InN). Transmission electron microscopy (TEM and HRTEM) and scanning electron microscopy (SEM) images confirm the nanoparticle character and homogeneity of the as‐prepared samples. X‐ray diffraction (XRD), electron diffraction (EDX), elemental mapping, and UV/Vis, IR, and Raman spectroscopy investigations are used to confirm the incorporation of indium into the crystal structure of GaN. These nanoparticles, possessing adjusted optical properties, are expected to have potential applications in the fabrication of novel optoelectronic devices.     

Light Dynamics of the Retinal‐Disease‐Relevant G90D Bovine Rhodopsin Mutant

The RHO gene encodes the G‐protein‐coupled receptor (GPCR) rhodopsin. Numerous mutations associated with impaired visual cycle have been reported; the G90D mutation leads to a constitutively active mutant form of rhodopsin that causes CSNB disease. We report on the structural investigation of the retinal configuration and conformation in the binding pocket in the dark and light‐activated state by solution and MAS‐NMR spectroscopy. We found two long‐lived dark states for the G90D mutant with the 11‐cis retinal bound as Schiff base in both populations. The second minor population in the dark state is attributed to a slight shift in conformation of the covalently bound 11‐cis retinal caused by the mutation‐induced distortion on the salt bridge formation in the binding pocket. Time‐resolved UV/Vis spectroscopy was used to monitor the functional dynamics of the G90D mutant rhodopsin for all relevant time scales of the photocycle. The G90D mutant retains its conformational heterogeneity during the photocycle.     

A New Synthesis of Pteridines

A new synthesis of pteridines possessing a (substituted) (Z)‐3‐hydroxyprop‐1‐enyl group at C(6) is based on the acylation of 4‐amino‐5‐nitrosopyrimidines with dienoic acid chlorides, followed by a high‐yielding intramolecular hetero‐Diels–Alder cycloaddition and cleavage of the N? O bond leading to 4 . Thermolysis of the resulting pteridines 4 possessing a benzyloxy group at C(4) led to the products 5 , resulting from isomerisation of the 3‐hydroxyprop‐1‐enyl to an 3‐oxopropyl side chain, while the analogous pteridine 8 possessing an NH₂ group at C(4) remained unaffected.     

Bright,Multi‐responsive,Sky‐Blue Platinum(II) Phosphors Based on a Tetradentate Chelating Framework

A new class of highly efficient and stable, blue‐phosphorescent Pt^II complexes based on a tetradentate chelating framework has been found to exhibit highly sensitive and reversible responses to multiple external stimuli including temperature, pressure, and UV irradiation with distinct phosphorescent color switching—from blue to red or white. Intermolecular excimer formation is the main origin of this intriguing multi‐response phenomenon. Highly efficient singlet‐oxygen sensitization by the Pt^II compounds yields UV‐light‐induced phosphorescence enhancement and color switching.     

Coordination‐Driven Dimerization of Zinc Chlorophyll Derivatives Possessing a Dialkylamino Group

Zinc chlorophyll derivatives Zn‐1 – 3 possessing a tertiary amino group at the C3¹ position have been synthesized through reductive amination of methyl pyropheophorbide‐d obtained from naturally occurring chlorophyll‐a . In a dilute CH₂Cl₂ solution as well as in a dilute 10 %(v/v) CH₂Cl₂/hexane solution, Zn‐1 possessing a dimethylamino group at the C3¹ position showed red‐shifted UV/Vis absorption and intensified exciton‐coupling circular dichroism (CD) spectra at room temperature owing to its dimer formation via coordination to the central zinc by the 3¹‐N atom of the dimethylamino group. However, Zn‐2/3 bearing 3¹‐ethylmethylamino/diethylamino groups did not. The difference was dependent on the steric factor of the substituents in the tertiary amino group, where an increase of the carbon numbers on the N atom reduced the intermolecular N⋅⋅⋅Zn coordination. UV/Vis, CD, and ¹H NMR spectroscopic analyses including DOSY measurements revealed that Zn‐1 formed closed‐type dimers via an opened dimer by single‐to‐double axial coordination with an increase in concentration and a temperature decrease in CH₂Cl₂, while Zn‐2/3 gave open and flexible dimers in a concentrated CH₂Cl₂ solution at low temperature. The supramolecular closed dimer structures of Zn‐1 were estimated by molecular modelling calculations, which showed these structures were promising models for the chlorophyll dimer in a photosynthetic reaction center.     

Differential Photosynthetic Response of a Green Tide Alga Ulva linza to Ultraviolet Radiation,Under Short‐ and Long‐term Ocean Acidification Regimes

Both ocean acidification (OA) and solar ultraviolet (UV) radiation can bring about changes in macroalgal physiological performance. However, macroalgal responses to UV radiation when acclimatized to OA under different time scales are rare. Here, we investigate the response of Ulva linza, a green tide alga, to UV radiation in the form of photosynthetically active radiation (PAR) or PAB (PAR+UVA+UVB) radiation. Radiation exposures were assessed following long‐term (from spore to adult stage, 1 month) and short‐term (adult stage, 1 week) OA treatments. Results showed that increased CO₂ decreased the damage rate (k) and repair rate (r) of thalli grown under short‐term OA conditions with PAB treatment, the ratio of r:k was not altered. Following long‐term OA conditions, r was not affected, although k was increased in thalli following PAB treatment, resulting in a reduced ratio of r:k. The relative level of UV inhibition increased and UV‐absorbing compounds decreased when algae were cultured under long‐term OA conditions. The recovery rate of thalli was enhanced when grown under long‐term OA after UV radiation treatment. These results show that blooming algae may be more sensitive to UV radiation in marine environments, but it can develop effective mechanisms to offset the negative effects, reflecting acclimation to long‐term OA conditions.