Abstract-Poly-hexamethylene biguanide hydrochloride (PHMB) and 1-bromo-3-chloro-5,5-dimethylimidazolidine-2,4-dione (BCDMH) are widely used for surface disinfection. Here, we examined the bactericidal effects of the mixture of PHMB and BCDMH (named PB) combined in different ratios on S. aureus, and studied effects of temperature, pH and bovine serum albumin (BSA , as organic interferent) on PB bactericidal activity with suspension quantitative germicidal method. We also observed surface structure changes and ATP level in S. aureus treated with PB with scanning electron microscope and multi-function microplate reader, respectively. The results showed that mixture of 10 mg/L PHMB and 10 mg/L BCDMH could meet the bactericidal requirements according to Technical Standard for Disinfection (China 2002), producing similar bactericidal activity to those exhibited by 320 mg/L PHMB and 60 mg/L BCDMH, separately. The results showed that PB was competent to kill bacteria quickly and bactericidal activity increased with time within 12 min. Temperature had no significant effect on PB bactericidal activity. PB offered satisfied bactericidal activity within 3.0 to 5.0 pH range. BSA significantly reduced bactericidal activity of PB. In addition, PB treatment could result in protuberance on S. aureus surface, and bring about a rapid decline in intracellular ATP level.
Background The disinfectants polyhexamethylene biguanide (PHMB) and 1-bromo-3-chloro-5,5-dimethylimidazolidine-2,4-dione (BCDMH) each have limitations. So far, their combined usage has not been examined. In this study, the fungicidal activity of combined disinfectant using PHMB and BCDMH, named PB, against Candida albicans was evaluated. Methods Suspension quantitative fungicidal test and viable fungi count were used to test fungicidal effects against C. albicans. Coupon corrosion testing was used to evaluate disinfectants' corrosive effects on stainless steel, copper, and aluminum. The mouse lymphoma assay was used to detect mutations induced by PB. Results and Discussion Fungicidal activity of the combination of 40 mg/L PHMB and 40 mg/L BCDMH was comparable to, or even better than, those of 600 mg/L PHMB or 640 mg/L BCDMH alone. The combination of 400 mg/L PHMB and 400 mg/L BCDMH exhibited good fungicidal effects in field applications. The combination of 100 mg/L PHMB and 100 mg/L BCDMH did not have corrosive effects on stainless steel and no mutagenic effect was observed under the test conditions. Conclusions The combination of PHMB and BCDMH has strong fungicidal effects and little metal corrosive and mutagenic effect and can be used as one suitable fungicide for wide household and industrial applications, including shipping containers.
In higher plants, phosphomannomutase (PMM) is essential for synthesizing the antioxidant ascorbic acid through the Smirnoff-Wheeler pathway. Previously, we characterized six PMM genes (TaPMM-A1, A2, B1, B2, D1 and D2) in common wheat (Triticum aestivum, AABBDD).Here, we report a molecular genetic analysis of PMM genes in Triticum monococcum (A m A m ), a diploid wheat species whose A m genome is closely related to the A genome of common wheat. Two distinct PMM genes, TmPMM-1 and TmPMM-2, were found in T. monococcum. The coding region of TmPMM-1 was intact and highly conserved. In contrast, two main TmPMM-2 alleles were identified, with TmPMM-2a possessing an intact coding sequence and TmPMM-2b being a pseudogene. The transcript level of TmPMM-2a was much higher than that of TmPMM-2b, and a bacterially expressed TmPMM-2a recombinant protein displayed relatively high PMM activity. In general, the total transcript level of PMM was substantially higher in accessions carrying TmPMM-1 and TmPMM-2a than those harboring TmPMM-1 and TmPMM-2b. However, total PMM protein and activity levels did not differ drastically between the two genotypes. This work provides new information on PMM genes in T. monococcum and expands our understanding on Triticeae PMM genes, which may aid further functional and applied studies of PMM in crop plants.
The bactericidal activities of polyhexamethylene biguanide hydrochloride (PHMB), 1-bromo-3-chloro-5,5-dimethylimidazolidine-2,4-dione (BCDMH) and the combination of the two (designated as PB) were compared using Escherichia coli as the test organism. PB exhibited strong bactericidal activity: 10 mg/L PHMB combined with 8 mg/L BCDMH resulted in approximately 5.74 log10 reduction (LR), whereas 320 mg/L PHMB or 20 mg/L BCDMH was about 5.53 and 6.56 LR, respectively. Analyses using scanning electron microscopy, flow cytometry and atomic absorption spectroscopy indicated that PB, PHMB and BCDMH disrupted cell membranes and changed membrane structure and permeability, resulting in the leakage of intracellular soluble proteins and ions. PB exerted stronger effects on potassium and magnesium leakage, membrane potential and permeability than BCDMH did. PB caused less protein leakage than PHMB did. These results suggest that at a relatively low concentration, PB exhibited good bactericidal activity and physiological effect on E. coli.
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