Algicidal bacteria MaI11-2, MaI11-5 and MaI11-10, which inhibited the growth of a harmful bloom-forming cyanobacterium Microcystis aeruginosa, were isolated from a sewage treatment plant. The isolate MaI11-5 was phylogenetically affiliated into the genus Pedobacter, while MaI11-2 and MaI11-10 were closely related to Bacillus aerophilus, Bacillus altitudinis and Bacillus stratosphericus with 100% identity based on 16S ribosomal RNA sequences. Co-cultivation of M. aeruginosa with the algicidal isolates showed their high algicidal activity. MaI11-5 showed the highest inhibitory effect on the cyanobacterial growth: the inhibitory effect exceeded 50% after 2 days, and reached to 75-85% after 10 days, regardless of the bacterial cell density. The cyanobacterial cells aggregated and produced mucilaginous, glycocalyx-like compounds when attacked by the algicidal bacteria. These results suggest that the algicidal bacteria isolated in the present study are potentially useful as biocontrol agents against M. aeruginosa bloom.
We evaluated the cytotoxicity of antiglaucoma ophthalmic solutions preserved with the same concentration of benzalkonium chloride (BAK) in four cultured corneal and conjunctival cell lines. The viability of cell cultures was determined following the exposure of cells to timolol maleate, dorzolamide, and their fixed combination, Kosoputo® (MSD, a Japanese formulation of Cosopt® (Merck) ) , and two commercially available eyedrop solutions, 0.5% Timpotol® (containing 0.5% timolol maleate, MSD) and 1% Trusopt® (containing 1% dorzolamide, MSD) for varying exposure times and at various dilutions using the MTT and neutral red assays. All the three commercially available eyedrop solutions tested in this study were preserved with 0.005% BAK. The toxicity of each solution was compared using the % cell viability score (CVS) . Cell viability was also subjected to statistical analysis using ANOVA, Dunnett's multiple comparison tests and a chi-square test. %CVS50/%CVS40/80s for the tested solutions were 53/-13 for 0.5% Timoptol®, 100/88 for preservative-free 0.5% timolol maleate, 50/ -10 for 1% Trusopt®, 72/100 for preservative-free 1% dorzolamide, and 44/ -17 for Kosoputo®. The results of statistical analysis were consistent to them. In conclusion, Kosoputo® had greater cytotoxicity than each component; however, in actual use it may have the advantages of reduced toxicity (side effect) due to reduced instillation frequency, and better patient adherence to the treatment regimen as well as a comparable pressure reduction effect.
We evaluated the in vitro cytotoxicity of benzalkonium chloride (BAK) -containing antiglaucoma eyedrops. We prepared cell cultures of SIRC, BCE C/D-1b, RC-1, and Chang conjunctiva. The viability of cell cultures was determined using the MTT and neutral red assays. The cell viability score (CVS) was used to compare the toxicity of test solutions. %CVS50 and %CVS40/80 of each eyedrop solution were 71 and 26 for Lumigan® (0.002% bimatoprost with 0.005% BAK) , 100 and 99 for Tapros® (0.0015% tafluprost, a new formula from 2010 with 0.001% BAK) , 39 and -29 for 2% Trusopt® (2% dorzolamide with 0.0075% BAK) , 28 and -43 for Xalacom® (latanoprost/0.5% timolol with 0.02% BAK) , 88 and 66 for DuoTrav® (travoprost/0.5% timolol with no BAK) , 36 and -35 for Cosopt® (2% dorzolamide/0.5% timolol with 0.0075% BAK) and 53 and -1 for Combigan® (0.15% brimonidin/0.5% timolol with 0.005% BAK) . Only Xalacom® and Tapros® did not show an apparent decrease in %CVS as compared to the corresponding concentration of BAK. In conclusion, the cytotoxicity of tested eyedrops was dependent on BAK. Only the eyedrops containing latanoprost or tafluprost showed a reduction in the cytotoxicity of BAK.
We investigated the microbicidal effect of weak acid hypochlorous solutions of pH 5.0 - 6.0, produced by mixing NaClO and HCl in water, against various bacteria, fungi, and virus in vitro. The weak acid hypochlorous solution had excellent microbicidal effect against a broad microbicidal spectrum of standard strains and clinical isolates in a short time. The microbicidal effects of hypochlorous solutions did not depend on the available chlorine concentration but on the HClO concentration. These results show that the weak acid hypochlorous solution has practical applicability in such places as hospitals and establishments related to the food industry.
An in vitro microbial challenge test has been developed to predict the likelihood of consumer contamination of baby shampoo. Four preservatives were tested in our study: the parbens Medcide D, Medcide PB, Sepicide HB. and isothiazolinone Methylisothiazolinone/ Chloromethylisothiazolinone [MI/MCI]. These preservatives were tested separately and in combination. The challenge test involved inoculating the product with Micrococcus luteus, Staphylococcus aureus, Escherichia coli, Salmonella enterica, Pseudomonas aeruginosa, Aspergillus brasiliensis and Candida albicans. Inhibition growth of these microorganisms at each preservative concentration was followed over a 28 d period. The test was used to classify products as poorly preserved, marginally preserved, or well-preserved. Interestingly, it was the combination (0.1% Isothiazolinone [MI/MCI] and 0.1% Sepicide HB) which inhibited most the microbial growth of microorganims while preserving the physicochemical properties of the product. As a result, the challenge test described can be accurately used to predict the risk of consumer contamination of cosmetic products.
Bacteria capable of degrading 4-nonylphenol (NP) were isolated and identified, and their ability to degrade NP was determined. The screening of microorganisms in river water and soil led to a collection of 23 strains of bacteria and five strains of fungi. Two strains of bacteria, identified as Pseudomonas sp. and Acidovorax sp., possessed great ability for degrading NP. The NP degradation rate of Pseudomonas sp. did not change with the NP concentration (50-100mg/L) . In contrast, the NP degradation rate of Acidovorax sp. increased with increasing NP concentration. Acidovorax sp. possessed the greatest NP degradation activity at 35°C. No NP degradation activity was observed for Pseudomonas sp. at temperatures higher than 30°C. Even when non-NP carbon sources such as glucose or sucrose were added, the NP degradation rates for both bacteria did not decrease. In addition, the estrogenic activity of NP decreased depending on the amount of NP residues determined by the yeast two-hybrid system.
Compact Dry ETBR (CD-ETB, ETB; Enterobacteriaceae) , a ready-to-use and self-diffusible dry medium sheet culture system for the detection and enumeration of Enterobacteriaceae, was evaluated. A total of 35 Enterobacteriaceae strains, which were studied for the inclusivity study, grew and formed red-purple colored colonies on the CD-ETBR. When 17 gram-negative bacteria other than Enterobacteriaceae were inoculated for the exclusivity study, 2 strains grew and formed red-purple colonies, 9 strains formed colorless colonies, and 6 strains failed to grow. A total of 43 gram-positive bacteria and 3 yeasts failed to grow. The CD-ETB method was compared with the Violet Red Bile Glucose (VRBG) agar method according to ISO 21528-2 and the 3M PetrifilmTM EB (3M-EBR) method in 53 meat samples. The correlation coefficients between CD-ETBR and VRBG agar, CD-ETBR and 3M-EBR, and 3M-EBR and VRBG agar were 0.962, 0.992 and 0.960, respectively.