Sixty-seven strains of pink-pigmented bacteria, which were isolated from environmental water samples collected nationwide, were identified by partial 16S rDNA sequence analysis. In addition, the biofilm formation ability of the isolates was experimentally investigated. We could identify only 2 strains at the species level: Pedobacter roseus HS-38 and Runella slithyformis HS-77. The results showed that of the strains tested, 22 strains (32.8%) were Pedobacter spp., which was most frequently identified, followed by 19 strains (28.4%) of Arcicella spp., 16 strains (23.9%) of Deinococcus spp., 5 strains (7.5%) of Roseomonas spp., 4 strains (6.0%) of Flectobacillus spp. and 1 strain (1.5%) of Runella sp. Most isolates showed low similarity values to previously known species, and they were found to be novel species. At a result, it was difficult to identify environmental water-derived pink-pigmented bacteria at the species level. On the other hand, when we measured the absorbance by the crystal violet staining to examine the quantities of biofilm formation of these strains, fifty-five (82.0%) of the 67 isolates formed biofilm. The absorbance of Deinococcus sp. HS-75 was the highest (3.56). When comparing the absorbance values among the genera, Roseomonas spp. showed the highest absorbance (mean: 1.62), followed by Deinococcus spp.(mean: 1.03), and Arcicella spp.(mean: 1.01). Strains of Flectobacillus spp.(mean: 0.48) and Pedobacter spp.(mean: 0.42) showed lower absorbance values. As above, it was shown that, at the species level, the pink-pigmented bacteria in the water in the Japanese environment had various levels of ability to form biofilm.
The aim of this study is to develop a growth inhibitory material against some pathogenic microorganisms, using beneficial bacteria such as Bifidobacterium species and certain types of vegetables which can be good substrates for the growth of the beneficial bacteria. At first, various vegetable juices were screened for the growth promotion of Bifidobacterium longum etc. Among the vegetables tested, broccoli (Brassica oleracea L. var. botrytis L.) and cabbage (Brassica oleracea L. var. capitata L.) showed excellent growth promoting activities for B. longum. Secondly, the B. longum-fermented broccoli (BFB) and Lactobacillus pentosus-fermented broccoli (LFB) supernatants were prepared and the growth inhibitory activities against Candida albicans were determined. Both of them showed dose-dependent, growth inhibitory effects, and the effect of BFB was superior to LFB. It was thought that the superior effect of BFB could be mainly attributed to the acids, especially acetic acid, produced by B. longum. BFB also inhibited some pathogenic bacteria such as Streptococcus mutans and Porphylomonas gingivalis. In conclusion, broccoli was found to be a good growth-promoting substance for B. longum. The fermented product, BFB, appears to be a usable material that inhibits the growth of C. albicans and some pathogenic bacteria.
To design new antimicrobial peptides, we have focused on various proteins which are not essential for self-defense but carry important responsibilities for biosystems. Previously, we reported that highly efficient antimicrobial properties or antiviral properties are inherent in the nuclear translocation signals and binding sites on laminin receptors. Here we introduce microtubule binding sites on tau proteins as new components for antimicrobial peptides. Strong antimicrobial activities against Staphylococcus aureus and Escherichia coil were found in tandem sequences of the binding sites on tau proteins. Moreover, the binding sites obtained significantly strong antimicrobial activities against bacteria and fungi when combined with a nuclear localization signal (NLS) and/or a peptide derived from a binding site of a laminin receptor. The antimicrobial activities of some of the tau-derived peptides were not affected by salt, cations, or serum that simulate the natural environment present in blood. Tau proteins so far have only been known as one of the microtubule-associated proteins (MAPs) which are especially abundant in the central nervous system within the brain. Our finding demonstrates that the binding sites on tau proteins possess high potential for becoming components in antimicrobial peptides. Designs based on binding sites of various proteins could become a useful method in peptide antibiotic research.
Type 316L stainless steel particles were pseudo-sensitized by being heated at 700°C for 100 h under a reduced pressure of 1.3×10-3 Pa. Pseudo-sensitization treatment resulted in the formation of chromium-rich precipitates at the outermost surfaces of the stainless steel particles. The curve for the apparent surface charge density (σapp) of the pseudo-sensitized particles showed a more basic character compared with the curve for the σapp of the original particles. There was no significant difference between the amounts of bovine serum albumin (BSA) adsorbed on the original and the pseudo-sensitized particles. On the contrary, the efficiency of BSA removal from the pseudo-sensitized particles during batch-wise and continuous cleaning operations with 0.1M NaOH solution were significantly smaller than that for the original particles. It was indicated that the extremely lowered cleanability of the pseudosensitized particles was caused by a marked increase in the positive a σapp values after the pseudo-sensitization. Solution treatment of the pseudo-sensitized particles at 1, 050°C for 1 h under a reduced pressure of 1.3×10-3 Pa could put again the chromium precipitates into a solid solution, thereby returning the surface chemical composition and the σapp nearly to the original states. In addition, the solution-treated particles showed a good cleanability comparable to that of the original particles. These results demonstrated that solution treatment could improve the lowered cleanability of the pseudo-sensitized stainless steel surfaces.
Microbes have been used for cleaning polluted environments and degrading unwanted compounds. This study assessed the feasibility of using three microbial adherent carriers, Isolite®, activated carbon fiber (ACF), and a marine sediment solidified carrier, MSSC, which was newly developed from dredged waste marine sediment, to remove nitrogen in sediment. The properties of three carriers were investigated, and the extent of microbe adhesion to the carriers was observed by using scanning electron microscopy. The amount of nitrogen removed by MSSC was higher than that removed by Isolite® and ACF. We concluded that MSSC may be useful as a microbial adherent carrier.