No abstract

We investigated selective cultivation media and previous treatments of samples suitable for detection of Legionella species from environmental water and for elimination of co-existing microbes which gave rise to an interference with the evaluation of Legionella sp. growth. Twenty thousand U of polymyxin B (PL-B)/ml and 100 micrograms of oxytetracycline (OTC)/ml seem to be useful as additives to MWY selective agar medium. Both antibiotics markedly inhibited the growth of co-existing microbes with almost no influence on the growth of Legionella sp. In the studies on the resistance of 8 strains of Legionella sp., 24 strains of co-existing microbes and 2 standard strains of Staphylococcus aureus and Escherichia coli to acid treatment (0.2 M HCl-KCl, pH 2.2, 25 degrees C, 4 minutes) and heating (50 degrees C, 20 minutes), acid treatment or heating alone showed no inhibition on the growth of almost all strains examined. However, combination with acid treatment after heating resulted in an apparent extinction of almost all microbes except for Legionella sp., Seven strains from co-existing microbes showed an apparent growth inhibition against 8 strains of Legionella sp. with different serotypes and were all identified as Pseudomonas aeurginosa, which were all eliminated by means of the combination with acid treatment after heating. From these results, it was concluded that the combined pre-treatment of water samples with acid after heating and the addition of PL-B and OTC into the selective cultivation medium is an useful method for detection of Legionella sp. from environmental water.

Inkjet technology was used in a mass production process to form an alignment layer on high-temperature polysilicon TFT liquid crystal panels used in LCD projectors. This is the first-ever inkjet process for forming alignment layers in an LCD manufacturing process.Surface treatment, inkjet ejection, and post-print drying processes were integrated, and process conditions and printing materials were optimized, thereby sharply improving display quality while reducing process environmental impact.

Anti-microbial effect of the pretreatment with various organic acid buffer solutions against co-existing microorganisms which were isolated from cooling-tower water samples along with Legionella spp. was examined. Among several buffer solutions, a 0.1 M potassium citrate-citric acid buffer solution (hereafter, citrate buffer solution, pH 2.2) hardly affected the recovery of Legionella spp., but effectively inhibited the growth of co-existing microorganisms. To evaluate the buffer action of these buffer solutions, pHs of 9 cooling-tower water samples were evaluated after addition of an equal volume of each buffer solution. When a citrate buffer solution. pH 2.2 was combined to a 200-fold concentrated solution of each cooling-tower water sample, the pH of the combined solution became 2.5 to 2.7 and maintained a stably low pH value than that (pH 3.0 to 7.4) obtained after mixture of a 0.2 M HCl-KCl buffer solution (hereafter, HCl buffer solution, pH 2.2), suggesting strong buffer action of the citrate buffer solution, pH 2.2 in the combined solutions. Furthermore, when cooling-tower water samples were pretreated with a citrate buffer solution, pH 2.2, the recovery of Legionella spp. was successful in 7 out of 9 cooling-tower water samples, suggesting 3 times higher recovery rate than that obtained by addition of a HCl buffer solution, pH 2.2 (3 out of 9 cooling-tower water samples).

To examine the optimal pH range for growth on media, growth of Legionella spp. on its selective media, BCYE alpha, WYO alpha and MWY agar media, in a pH range of 6.0-8.0 (at 0.5 intervals) was compared. The growth of two strains of L. pneumophila and one strain of L. micdadei on a WYO alpha agar supplemented with some selecting antimicrobial agents was markedly inhibited at all pH range except 6.0 and 7.0, suggesting a narrow optimal pH range for growth of these species compared to the BCYE alpha without selecting antimicrobioal agents. Vancomycin (VCM) added to the selective agar suppressed the growth of some Legionella spp. depending on the concentration. However, the extent of suppression was different among species and/or strains of Legionella spp. The selectivity for species other than Legionella spp. was also affected similarly by VCM concentration added to their media, suggesting that it is important to use proper amounts of the selecting antimicrobial agent depending on the species and/or strains of Legionella spp. or the other species in water samples. Amphothericin B (AMPH-B) added to a selective medium, MWY agar, in the concentration of 80 micrograms/ml hardly affected the growth of Legionella spp. examined, but effectively inhibited the growth of fungal strains identified as Aspergillus sp., Trichoderma sp., Scolecobasidium sp. and Mucor sp. which were isolated from cooling-tower water samples together with Legionella spp. Furthermore, the growth of a combination culture of one each of the 4 strains of isolated fungi and one each of the 3 strains of Legionella spp. was examined at various concentration of AMPH-B. Addition of AMPH-B to the selective medium at the concentration of 80 micrograms/ml suppressed the growth of spreading fungi, permitting the growth of Legionella spp. to allow efficient detection of the species.