Phormidium Tenue Research Articles

Probing pH sensitivity of αC-phycoerythrin and its natural truncant: A comparative study

Cyanobacterial phycoerythrin (αC-PE) from Phormidium tenue exists in two natural forms named as full length (FL-αC-PE) and truncated (Tr-αC-PE). FL-αC-PE and Tr-αC-PE are produced when cyanobacterium is grown in the optimal medium and nutrient deficient medium, respectively. Despite of N-terminal deletion, both proteins show similar spectroscopic properties. In this study, different optical properties of these two natural variants of C-PE were measured in the pH range 1.0⿿12.0 (1.0⿤pH⿤12.0). It was observed that: (i) their absorption, fluorescence and CD spectra remain unchanged within the range adjacent to neutral pH, 5.5⿿8.75, (ii) at pH values higher than 8.75 and lower than 5.5 their absorption, fluorescence and CD spectral signatures are changed significantly, and (iii) emission spectra of the covalently linked tetrapyrrole chromophores and Trp residue are perturbed at extreme pH values in the range 8.75<pH<5.5. Refolding experiments further suggest that pH-induced denaturation of both forms of C-PE is reversible in the pH range 2.5⿿11.0, but irreversible beyond this range on both sides of pH extremes. The pH-induced denaturation of both the full length and truncated αC-PEs follows a two-state mechanism.

퇴적층의 온도별 배양에 따른 조류군집 형성과 이취미물질 발생 특성

We analyzed the formation of phytoplankton community and the occurences of odorus compound from benthic cyanobacteria in North, South Han-River, Paldang-Lake and Kyeongan-Stream sediments. Sediments were incubated in different water temperature. Akinetes were found (0~500 cells/g) with the highest number on sediment in Yangsoo railroad bridge (YC). The result showed that Anabaena ranged between in Sambong (SB), YC, Mukhyen-Stream (MS), Paldang-Lake (P2) and Kyeongan-Stream (KK). The total 68 taxa of phytoplankton were observed during the incubation period. A standing crop of phytoplankton was in the range of and Microcystis appeared in SB, YC, P2 and KK sites with temperature. In South Han-River (P3), Oscillatoria tenuis was dominant at temperature. The concentration of geosmin was the highest in SB- (25.5 ng/L), and the concentration of 2-MIB was the highest in P3- (286.8 ng/L). Odorous compounds were detected in all the temperature conditions from each site. Our results indicate that the dominant benthic cyanobacteria (O. tenuis, O. limosa, Phormidium tenue and Pseudanabaena limnetica) have high correlation with the occurrence odorous compounds and 2-MIB.

Estimating Cyanobacteria Community Dynamics and its Relationship with Environmental Factors

The cyanobacteria community dynamics in two eutrophic freshwater bodies (Tiegang Reservoir and Shiyan Reservoir) was studied with both a traditional microscopic counting method and a PCR-DGGE genotyping method. Results showed that cyanobacterium Phormidium tenue was the predominant species; twenty-six cyanobacteria species were identified in water samples collected from the two reservoirs, among which fourteen were identified with the morphological method and sixteen with the PCR-DGGE method. The cyanobacteria community composition analysis showed a seasonal fluctuation from July to December. The cyanobacteria population peaked in August in both reservoirs, with cell abundances of 3.78 × 108 cells L-1 and 1.92 × 108 cells L-1 in the Tiegang and Shiyan reservoirs, respectively. Canonical Correspondence Analysis (CCA) was applied to further investigate the correlation between cyanobacteria community dynamics and environmental factors. The result indicated that the cyanobacteria community dynamics was mostly correlated with pH, temperature and total nitrogen. This study demonstrated that data obtained from PCR-DGGE combined with a traditional morphological method could reflect cyanobacteria community dynamics and its correlation with environmental factors in eutrophic freshwater bodies.

Role of N-terminal residues on folding and stability of C-phycoerythrin: simulation and urea-induced denaturation studies

The conformational state of biliproteins can be determined by optical properties of the covalently linked chromophores. Recently determined crystal structure of truncated form of α-subunit of cyanobacterial phycoerythrin (αC-PE) from Phormidium tenue provides a new insight into the structure–function relationship of αC-PE. To compare their stabilities, we have measured urea-induced denaturation transitions of the full length αC-PE (FL-αC-PE) and truncated αC-PE (Tr-αC-PE) followed by observing changes in absorbance at 565 nm, fluorescence at 350 and 573 nm, and circular dichroism at 222 nm as a function of [urea], the molar concentration of urea. The transition curve of each protein was analyzed for ΔGD0, the value of Gibbs free energy change on denaturation (ΔGD) in the absence of urea; m, the slope (=∂∆GD/∂[urea]), and Cm, the midpoint of the denaturation curve, i.e. [urea] at which ΔGD = 0. A difference of about 10% in ΔGD0 observed between FL-αC-PE and Tr-αC-PE, suggests that the two proteins are almost equally stable, and the natural deletion of 31 residues from the N-terminal side of the full length protein does not alter its stability. Furthermore, normalization of probes shows that the urea-induced denaturation of both the proteins is a two-state process. Folding of both structural variants (Tr-αC-PE and FL-αC-PE) of P. tenue were also studied using molecular dynamics simulations at 300 K. The results show clearly that the stability of the proteins is evenly distributed over the whole structure indicating no significant role of N-terminal residues in the stability of both proteins.

Soft x-ray imaging of intracellular granules of filamentous cyanobacterium generating musty smell in Lake Biwa

A planktonic blue-green algae, which are currently identified as Phormidium tenue, was observed by a soft x-ray microscopy (XM) for comparing a musty smell generating green strain (PTG) and a non-smell brown strain (PTB). By XM, cells were clearly imaged, and several intracellular granules which could not be observed under a light microscope were visualized. The diameter of granules was about 0.5–1 μm, and one or a few granules were seen in a cell. XM analyses showed that width of cells and sizes of intracellular granules were quite different between PTG and PTB strains. To study the granules observed by XM, transmission in more detail, transmission electron microscopy (TEM) and indirect fluorescent-antibody technique (IFA) were applied. By TEM, carboxysomes, thylakoids and polyphosphate granules were observed. IFA showed the presence of carboxysomes. Results lead to the conclusion that intracellular granules observed under XM are carboxysomes or polyphosphate granules. These results demonstrate that soft XM is effective for analyzing fine structures of small organisms such as cyanobacterium, and for discriminating the strains which generates musty smells from others.

MICROBIAL DIVERSITY AND DENSITY IN THE CORAL REEF ENVIRONMENT OF THE GULF OF MANNAR

Microbes are important in the coral reef environmen t in the recycling of nutrients and as a source of food to a variety of animal species. They also have an important trophic role to play in the reef environment, goverened by different physico-chemical and biotic factors. The present study has reveale d the presence of more THB (total heterotropic bacter ia) population density in water (5.2 to 22.5 ◊ 10 5 CFUml -1 ) and in the sediments (7 to 24.2 ◊ 10 7 CFUg -1 ) than in the surrounding coastal environments. A total of 24 species of planktonic cyanobacteria and 11 species of benthic cyanobacteria were recorded. Among them, Phormidium tenue was the most dominant species and the families Osc illatoriaceae and Chroococcaceae were predominant in the present study. A total of 35 species of fungi belonging to 20 genera representing the families Labyrinthulomycete s, Oomycetes, Zygomycetes and Deuteromycetes were isolated. Among them, the deuteromycetous fungi formed the bulk of the mycoflora of all the samples at both stations.

Use of cyanobacterial polysaccharides to promote shrub performances in desert soils: a potential approach for the restoration of desertified areas

The importance of cyanobacterial polysaccharides of biological soil crusts in sand surface stabilization and soil nutrient retention has been long acknowledged. However, the role of cyanobacterial polysaccharides as a source of nutrition to vascular plants in crusted areas is ignored. In this study, the chemical composition of the polysaccharide synthesized by Phormidium tenue and the effects of its presence on seed germination and seedling metabolism of the shrub Caragana korshinskii were investigated. The crude polysaccharide synthesized by P. tenue was composed of 15 % protein and 58 % carbohydrate and showed the presence of 12 different types of monosaccharides. The addition of the polysaccharide significantly (P < 0.05) increased seed germination and metabolic activity of the seedling of the shrub C. korshinskii. The optimal concentration for vigor index, root length, root vigor, and total N and P contents was 10 mg/L polysaccharide; for the germination rate, nitrate reductase activity, carbohydrate content, chlorophyll, and Mg2+ content, the optimal was 60 mg/L polysaccharide, while for K+ and Ca2+ contents, photosynthetic efficiency and superoxide dismutase activity was 120 mg/L. The presence of the polysaccharide increased seed germination rate, ion uptake, and photosynthetic activity by affecting the electron transport chain and decreased oxidative damage by eliminating reactive oxygen species in C. korshinskii, thus promoting shrub performance in crusted desert areas.

The species composition cyanobacteria in the cultivated soils of Dak Lak and Dak Nong provinces

A total of 129 species and subspecies of cyanobacteria were found in the cultivating soils (rice, cotton and coffee) of Dak Lak and Dak Nong provinces. They belonged to 20 genera, 10 families, 4 orders. The Ocillatoriales order was the most diverse with 71 species and subspecies (55.03% total found species); the Nostocales order with 44 species and subspecies (55.03%); Chroococcales order: 7 species (5.43%); and Stigonematales order: 7 species (5.43%). They are morphologically diverse: fibrifrom with 122 species (94.57%); unicellular with 7 species (5.43%). Among them there are 5 genera, 11 species and subspecies exicting in 3 types of cultivated soils the genera are: Lyngbya, Microcoleus, Phormidium, Nostoc and Hapalosiphon; the species are Gloeocapsa montana, Lyngbya aerugineo-coerulea, Oscillatoria brevis, Phormidium corium, Phormidium tenue, Cylindrospermum licheniforme, Nostoc carneum, Nostoc linckia, Calothrix elenkinii, Hapalosiphon welwitschi, Hapalosiphon sp. Among them 1 genus (Westiellopsis Janet), 38 species and subspecies were firstly recorded in Vietnam. Of the cultivated soils of Daklak and Daknong provinces, the rice soil was determined to possess the most species of cyanobacteria (101 species and subspecies, 18 genera, 9 families, 4 orders), it was folowed by the cotton-paddy soil (55 species and subspecies, 14 genera, 8 families, 4 orders) and the coffee-planted soil showed the least (26 species and subspecies, 11 genus, 8 families, 4 orders).

Synthesis and characterization of CdS nanoparticles using C-phycoerythrin from the marine cyanobacteria

In the background that the marine cyanobacteria offer great potentials as source of fine chemicals, pharmaceuticals, biofuels, etc., in the present study the pigment, C-phycoerythrin (C-PE) extracted from the marine cyanobacterium, Phormidium tenue NTDM05 was used to synthesize CdS nanoparticles. The CdS nanoparticles thus synthesized were characterized adopting UV–Visible spectrum, Fourier transform infra-red spectrum, EDAX and transmission electron microscopy. The size of the CdS nanoparticles was found to be about 5nm. Essentially, it was found that the pigment stabilized the CdS nanoparticles. The pigments labeled CdS nanoparticles could be applied as a biolabel.

Characteristics of phytoplankton community structures in Ningwu subalpine lakes, Shanxi Province

通过对山西宁武亚高山湖群浮游植物群落结构的调查研究,共鉴定出浮游植物291个种、变种及变型,隶属于8门,45科,108属.各采样站点间种数相差较大,以马营海种类最多,干海最少.硅藻门、绿藻门和蓝藻门明显占优势,优势科、优势属和优势种也都较为明显.优势种有蓝藻门的细小隐球藻(Aphanocapsa elachista)、铜绿微囊藻(Microcystis aeruginisa)和小席藻(Phormidium tenue),硅藻门的库津小环藻(Cyclotella kuetzingii)、肘状脆杆藻(Fragilaria ulna)、尖针杆藻(Synedra acus),绿藻门的狭形纤维藻(Ankistrodesmus angustus)和小球藻(Chlorella vulgaris).浮游植物平均密度为3.49×106cells/L.水面下0.5 m处比水表层的细胞密度高.综合4种生物多样性指数,宁武亚高山湖群水质总体为轻污染.;The phytoplankton community structures in Ningwu subalpine lakes have been studied and 291 taxa, belonging to 8 divisions, 45 families and 108 genera, have been identified. The species numbers of each sampling station are quite different. The most abundant species are occurred in Lake Mayinghai, and the least in Lake Ganhai. Bacillariophyta, Chlorophyta and Cyanophyta dominate the area, in addition, dominant families, dominant genera and dominant species are also relatively clear. There are 8 dominant species and they are Aphanocapsa elachista, Microcystis aeruginosa, Phormidium tenue, Cyclotella kuetzingii, Fragilaria ulna, Synedra acus, Ankistrodesmus angustus and Chlorella vulgaris. The average phytoplankton cell density is 3.49×10⁶ cells/L in the lakes. The cell density in 0.5 m depth was higher than that on the surface. The initially assessment by four biodiversity indexes is that the water quality in Ningwu subalpine lakes is light-polluted.

The response of carbohydrate metabolism to the fluctuation of relative humidity (RH) in the desert soil cyanobacterium Phormidium tenue

The excreting of exopolysaccharides (EPS) is thought as one of the main protection ways for cyanobacteria in desert algal crusts to survive desiccation. But how cyanobacteria adjust their carbohydrate metabolism to survive this stress is not elucidated. In this study, we treated Phormidium tenue, a cyanobacterium isolated from biological soil crusts with the changes of relative humidity (RH) to simulate different levels of desiccation and investigated its carbohydrate metabolism. It was found that photosynthetic activity ( Fv/Fm) and cellular total carbohydrates production decreased significantly at low RH. But the production of EPS, reducing sugar, sucrose and the activity of sucrose phosphate synthase (SPS) increased significantly at low RH and reached maximum at 75% RH. Low RH could also cause the enhanced production of reactive oxygen species (ROS) generation, malondialdehyde (MDA) production and DNA strand breaks. However, when pretreated with exogenous 100 mg/L EPS, Fv/Fm and carbohydrate production were improved significantly, while ROS generation, MDA production and DNA strand breaks decreased significantly at various levels of RH in P. tenue. These results indicated that P. tenue in arid regions could enhance desiccation tolerance by adjusting the carbohydrate metabolism to eliminate ROS and decrease oxidative damage.

Occurrence of airborne algae within the township of Bukit Jalil in Kuala Lumpur, Malaysia

There have been relatively few studies on airborne algae although they are known to have health implications. The aim of this study was to conduct a survey on the distribution of airborne algae within Bukit Jalil in Kuala Lumpur, Malaysia. The sampling sites included a quiet residential area, a busy area with high human movement, a highway with heavy traffic, small roads with low traffic, a golf course, two hilly areas, and the man-made lake, Tasik Komanwel. Soils were also collected from these sites when possible. Results based on cultured samples showed that cyanobacteria were the dominant airborne algae, with a total of eight species identified. The dominant species was Phormidium tenue while other airborne algae found included P. retzii, Nostoc commune, and N. linckia. The sites with high percentage occurrence of airborne algae were near the animal holding facility of the International Medical University and the Light Railway Transit station. Human movement could be an important factor affecting the occurrence of airborne algae. A very low occurrence of airborne algae was recorded at the sites around the lake area. Some of the airborne algae were also found in the soil samples, suggesting that the algae could originate from the soil.

Biological characteristics of the improved extensive shrimp system in the Mekong delta of Vietnam

Low and unstable shrimp yields of the improved extensive shrimp system has been a tremendous obstacle for economic development in the coastal areas of Southern Vietnam. To investigate the biological characteristics of this system, ponds in the coastal Cai Nuoc district, Mekong delta of Vietnam, were monitored. Results showed that the system was not optimal for shrimp. While chlorophyll a (chl a) (1.51–37.2 μg L−1), phytoplankton density (6333–974 444 cells L−1) and zooplankton density (7.1–517.2 ind L−1) were abundant and comparable to shrimp farms elsewhere, zoobenthic community was very poor (7–1971 ind m−2). Toxin-producing cyanobacteria (Oscillatoria limosa, Oscillatoria formosa, Anabaena sp. and Phormidium tenue) were found. Total bacteria and Vibrios were present in large numbers (respectively 1.04 × 105 and 6.64 × 102 CFU mL−1 in pond water, 6.33 × 105 and 9.47 × 103 CFU g−1 in sediment). Presence of toxin-producing organisms, poor zoobenthic community and abundance of Vibrios all can enhance shrimp susceptibility to diseases. The following measures are recommended to improve the situation: (1) complete testing of seeds for pathogens, (2) not to incorporate fish into shrimp ponds and (3) applying no-culture breaks and pathogen-killing chemicals.

Assimilable organic carbon generation from algogenic organic matter in drinking water

A study of assimilable organic carbon (AOC) derived from algogenic organic matter in different drinking water resources was conducted. Seasonal changes in the concentration of AOC at Kamafusa Dam were dependent on the algal cell numbers. Variations in AOC concentrations were found to be more reliant on the AOC-P17 component than the AOC-NOX component. The algal culture experiment showed that extracellular organic matter (EOM) released during the growth of Phormidium tenue in M-11 culture medium led to a significant increase in AOC concentration; however, no significant variations of AOC concentration were observed in CT culture medium containing high amounts of dissolved organic matter. The AOC included in EOM was not easily removed by chlorination; however, the AOC included in intercellular organic matter (IOM), which was released from algal cells, was easily removed under conditions where residual chlorine was detected.

Comunidades algales bentónicas de algunas fuentes del marjal Oliva-Pego, Comunidad Valenciana, España

Benthic algal communities of some sources of the Oliva-Pego marsh, Valencia, Spain The Oliva-Pego marsh is an important rice and citrus growing area in the Spanish Levant. The marsh is situated in the area of maximal rainfall of the Autonomous Community of Valencia and has high temperatures year-round. This marsh presents a conductivity gradient that goes from fresh water to brackish in its main inflowing streams, which gives way to a large variety of macro and microalgae, that form characteristic groups in the different conditions. Several of these species show tropical afnity. The results of two samplings in 1999 are presented, which were carried out in the most contrasting environmental zones -those of minimum and maximum rainfall. In each sampling site (four water bodies: Bullent River, Ullal River close to the Bullent, Bassa Sineu and the Font Sallat) pH, temperature, electrical conductivity, dissolved oxygen, current velocity, depth, and cationic and anionic contents of the water were assessed. The communities studied were constituted by structural species of Cyanophyceae and Chlorophyceae. Diatoms were the most diverse group, while Cyanophyceae and Chlorophyceae formed the visible elements. As structural elements, the presence of Homoeothrix juliana (Meneghini) Kirchner and Schizothrix fasciculata (NGomont was to be noteed in oligohaline wa- ters and Chaetophorales, Phormidium tenue (Meneghini) Gomont, Calothrix pulvinata K¨ utzing and Pleurocapsales in slightly brackish waters. The diatoms Encyonopsis microcephala Grunow Krammer, Cymbella afnis Kand Navicula cryptotenella Lange- Bertalot were responsible for their chlorophyll c contribution in two streams (R´ �o Bullent and Ullal), while Hyalodiscus whitneyi Ehrenberg, Nitzschia gracilis Hantzsch, Navicella pusilla (Grunow) Krammer and Cocconeis placentula var. eu- glypta (Ehrenberg) Grunow were responsible in Font Salat, and Rhoicosphenia abbreviata (C. Agardh) Lange-Bertalot was responsible in Bassa Sineu. Characteristic communities of the different degrees of water salinity were observed in the different water bodies, composed of species with afnity for those conditions. The sources in the marsh are fundamental as consistent providers of water, with a constancy in the species within the com- munity, This is why they can be used as equilibrium indicators of the system, in order to understand the combined effects of salinity and water regime on marsh biodiversity. This information is important as an environmental referent for water policies and legislative measures with water quality indicators of the Water Framework Directive (WFD) of the European Community (EC), and offers a precedent for the improvement of ecological quality of both freshwater and marine systems.

Photosynthetic and biochemical characterization of pigments and UV-absorbing compounds in Phormidium tenue due to UV-B radiation

We report the effect of UV-B radiation (0.8 ± 0.1 mW cm−2) and UV-B radiation supplemented with low-intensity PAR (∼80 μmol photons m−2 s−1) on the photosynthesis, photosynthetic pigments, phosphoglycolipids, oxidative damage, enzymatic antioxidants, and UV-absorbing compounds in Phormidium tenue, a marine cyanobacterium. UV-B radiation resulted in a decline in photosynthesis and photosynthetic pigments leading to lower biomass. P. tenue synthesized UV-absorbing compounds like mycosporine-like amino acids (MAAs) and scytonemin in response to UV-B radiation. Quantity of MAAs and scytonemin was higher when UV-B was supplemented with low-level PAR. UV-B treatment also resulted in quantitative changes in phosphoglycolipids of the membrane. The UV-B treatment resulted in a slight increase in the level of peroxidation of cell membrane and very little increase in the activity of superoxide dismutase (SOD). Results indicate that UV-B affected photosynthesis and that the main protective system was the synthesis of MAAs and scytonemin-like compounds rather than antioxidant enzymes such as SOD.

Structure of the novel 14kDa fragment of α-subunit of phycoerythrin from the starving cyanobacterium Phormidium tenue

The rod-like phycobilisome (PBS) in cyanobacterium is the light-harvesting complex of phycoerythrin (PE), phycocyanin (PC) and allophycocyanin (APC). The orderly degradation of PBS was observed under starvation conditions. A 14 kDa truncated fragment of alpha-subunit of PE (F-alphaPE) was identified from the degraded product. F-alphaPE was purified to homogeneity, sequenced and crystallized. The merohedrally twinned crystals with a twinning factor of approximately 0.5 were obtained. The crystal structure of F-alphaPE was determined with molecular replacement method using detwinned data and refined to an R(cryst) factor of 23.2% (R(free)=27.6%). The structure consisted of two crystallographically independent molecules in the asymmetric unit. The two molecules were designated as molecules A and B with a buried area of 200 A(2) at the interface. The structure of F-alphaPE consists of seven alpha-helices A, B, E, F, F', G and H. The first 31N-terminal residues that fold into parallel alpha-helices X and Y in other PEs are not present in the amino acid sequence of F-alphaPE. Both molecules, A and B contain two chromophore ligands, PEB1 and PEB2 in each. These are covalently linked to the polypeptide chain through Cys82 and Cys139, respectively. The superimposition of C(alpha) tracings of molecules A and B shows an r.m.s. shift of 1.0 A indicating that the structures of two independent molecules are very similar. The degradation of phycobilisome proteins under starvation stress seems to occur to supplement the requirement of amino acids for protein synthesis and to reduce the absorption of light energy.

Formation of Assimilable Organic Carbon from Algogenic Organic Matter

The objective of this study was to assess the variation in the concentration of assimilable organic carbon (AOC) in a drinking water resource, and investigate the characteristics of AOC derived from algae. The seasonal change in AOC at the Kamafusa dam corresponded to changes in the algal cell number. In order to understand the relationship between AOC and algae in a water resource and water purification plant, two kinds of laboratory experiment were performed. The algal culture experiment showed that extracellular organic matter (EOM) that was released during the growth of Phormidium tenue with M-11 medium led to significant increases in the AOC concentration, but no significant variation in the AOC concentration was observed with CT medium containing a high dissolved organic carbon concentration. The chlorination experiment showed that the AOC included in EOM was not easily removed by chlorination, although the AOC included in intercellular organic matter released from the algal cells by chlorination was removed under conditions where residual chlorine was detected.

Screening of a hypersaline cyanobacterium, Phormidium tenue, for the degradation of aromatic hydrocarbons: naphthalene and anthracene

Hypersaline Phormidium strains were grown in media amended with naphthalene and anthracene. Phormidium tenue was identified as tolerating and effectively degrading polycyclic aromatic hydrocarbons that may be toxic in the environment. GC/MS analysis explained the degradation of these compounds by P. tenue. A dioxygenase enzyme system was evident by the formation of anthracene dione as the first degradation compound. This strain could be used for bioremediation of polycyclic aromatic hydorcarbon pollution on seashores.

Prevention of Phormidium tenue Biofilm Formation by TiO2 Photocatalysis

We showed that the photocatalytic effect of a coating of TiO(2) greatly reduces the formation of a biofilm by Phormidium tenue (P. tenue), a filamentous cyanobacterium, on glass plates. Sample plates were immersed in P. tenue culture solution (OD(730)=0.3) under concurrent illumination with white fluorescent (WF) and UV light (0.3 mW cm(-2), each) for 11 days. TiO(2)-coated glass plates showed greatly reduced adhesion of P. tenue over 11 days compared to bare plates. The number of P. tenue adhering to bare glass plates increased to over 10(6) cells cm(-2) in 6 days. The photocatalytic anti-biofilm effect was also observed under WF light, although it was small and lasted only a few days. The addition of 1 mM mannitol, a scavenger for the hydroxyl radical (·OH), suppressed the effect. The surface of TiO(2)-coated plates was maintained in a highly hydrophilic state for 11 days, regardless of the addition of mannitol. Therefore, we conclude that the photocatalytic oxidation of P. tenue is effective in preventing the formation of a biofilm.