Acid treatment is performed in the detection of Legionella species from environmental water samples using the plate culture method. The acid treatment functions to eliminate the nontarget heterotrophic bacteria. Usually, an HCL-KCL buffer is used for the acid treatment of samples. However, the buffering capacity of the HCL-KCL buffer is not sufficient to maintain a constant low-pH in highly alkaline samples or highly buffered samples such asthose from cooling towers or spas. Our results show that the pH of various water samples ranged from 2.4 to 7.2 after treatment with an HCL-KCL buffer. We demonstrate here that an acid-phosphate buffer produces a low pH in highly alkaline samples or highly buffered samples. The pH of the water samples ranged from 2.2 to 2.5 after treatment with an acid-phosphate buffer. In the re-sults of the examination of 161 samples, the use of an acid-phosphate buffer instead of an HCL-KCL buffer decreased the effect of non-target heterotrophic bacteria from 3.1% to 1.2%. Therefore, efficient detection of Legionella from samples of varying water quality can be achieved following pretreatment with an acid-phosphate buffer.
Rayon fiber with the addition of titanium oxide (TiO2) silica (SiO2) complex was prepared, and its antibacterial property was mainly examined. When UV irradiation was applied to the fiber using a fade meter, the fiber with the addition of titanium oxide silica complex showed higher tensile strength even before UV irradiation and the degree of degradation of the fiber properties due to UV irradiation was small, compared with the rayon fiber with the addition of general titanium oxide phtocatalyst not containing silica. The antibacterial activity of the rayon fibers with the addition of the titanium oxide silica complex of different particle sizes was examined. The results showed that with a particle size of 90 nm, antibacterial activity was not recognized when the addition was 7.5% (w/w) or less, and it was seen with the addition of 10.0% (w/w). On the other hand, with the particle size of 30 nm, antibacterial activity was sufficiently expressed with the addition of only 5.0% (w/w). In addition, the surface of the fiber was observed with a scanning electron microscope. In the fiber with the addition of titanium oxide silica complex of 90 nm particle size, ruggedness appeared on the fiber surface when the addition reached 10.0% (w/w). However, in the case of 30 nm particle size, ruggedness appeared with the addition of 5.0% (w/w) and outcropping particles were seen. The results showed that there was agreement between the surface condition of the fiber and the expression of antibacterial activity, and that prediction of the antibacterial property of the rayon fiber with the addition of titanium oxide became possible through the SEM observation of the fiber surface. The rayon fiber developed by this research has been proven to show a very excellent antibacterial property.
New bis-type quaternary ammonium compounds (QACs), 1, 1'-(decanedioyl) bis (4-methy1-4-alkylpiperazinium iodide) s (DMAP-n, n: carbon number in the N-alkyl chains, n = 6, 8, 10, 12, 14, 16), which have a gemini structure containing two piperazinium rings connected with the spacer of the decanedioyl group, were developed. Their antimicrobial characteristics were investigated against 16 strains of bacteria and 9 strains of fungi and compared with those of 1, 4-dimethyl-1, 4-dialkylpiperazinium diiodides (DMPA-n), 1-methyl-1-alkylpiperazinium iodides (MPA-n), benzyldimethyldodecylammonium chloride (BAC) or 2-(4-thiazolyl)-benzimidazole (TBZ). DMAP-10 and DMAP-12 had the highest antimicrobial activity in the DMAP-n series against Escherichia coil K12 W3110 and Staphylococcus aureus IFO 12732. DMAP-12 also exhibited a wide-ranging antimicrobial spectrum, and showed more effective antimicrobial activity against bacteria than DMPA-12 and BAC, and more effective activity against fungi than DMPA-12 and TBZ. The activity of DMAP-12 was not influenced by pH and temperature like other bis-type QACs. It was found in the DMAP-n, DMPA-n and MPA-n series that the antimicrobial activity and hemolytic activity against human erythrocytes showed some correlation with their molecular hydrophobicity.
The DNA band patterns generated by PCR using Primer 4 and template DNAs from variousBacillus strains were compared. Sequence analysis of the 3.2 kb PCR product detected only in B. cereus revealed that the DNA sequence from base 11 to 2962 of the DNA seemed to contain a sequence specific to B. cereus. The primers BCF and BCR that amplify the region between base 1168 and 2320 of the 3.2 kb DNA generated the 1153 by PCR product with DNAs from B. cereus type strain JCM 2152, 3 cereulide-positive B. cereus strains and 20 strains among 49 B. cereus isolated from dairy products and processing factories. The same band was not amplified with those from 5 strains of B. thuringiensis, other 11 Bacillus species and 12 different bacteria which were not Bacillus.
Enterococcus faecalis TH10 is a lactic acid bacterial strain isolated from the Malaysian traditional fermented food, “tempeh”, and has antibacterial activity against various pathogens. To identify the antibacterial substance, the butanol extract of the culture supernatant of E. faecalis TH10 was fractionated by HPLC equipped with a reversed-phase partition column, and the elutes were subjected to antibacterial assay. As the activity was observed in a fraction eluted by ca 80% methanol, the fraction was analyzed by gas chromatography/mass spectrometry and 3-phenyllactic acid was identified as the major compound. Fractionation with an optical isomer separation column showed that the preparation contained D-and L-forms of 3-phenyllactic acid at a ratio of 2: 1. Authentic 3-phenyllactic acid showed antibacterial activity against various bacteria such as Staphylococcus aureus and Escherichia coil. These results suggest the possibility that 3-phenyllactic acid is a biopreservative.
Among microorganisms isolated from different origins, strain WW2 (a wastewater habitant) was selected as a bacterium showing high cell density on metal surfaces (1×108 and 1.51×108 cells/cm2 on stainless steel and copper, respectively, after two weeks of culture). From the physiological tests and homology analysis based on 16S rDNA, this strain was classified into the Enterobacteriaceae family and identified as a facultative anaerobe, Providencia sp. The attachment of WW2 cells to stainless steel surface was maximized when the growth medium was supplemented with 15 g/dm3 NaCI. From scanning electron microscopy and energydispersive X-ray spectroscopy observations of the copper wire immersed in WW2 culture without shaking, it was found that the wire surface was covered with black colored deposits mainly composed of copper and sulfur, the latter element possibly originating from the sulfide produced by WW2 cells under local oxygen-limited conditions.