학회지 리뷰

Pseudomonas aeruginosa, an opportunistic human pathogen, expresses LasA (elastase A) for infection as an important virulence factor. Since the LasA activity can be inhibited by its propeptide, we tried to alleviate the severity of P. aeruginosa infection using the purified LasA propeptide (LasA_pp). The purified LasA_pp efficiently inhibited LasA in vitro. The effectiveness of LasA_pp in alleviating the P. aeruginosa infection was investigated using mouse skin infection and acute lung infection models. The LasA_pp treatment of P. aeruginosa alleviated severity of P. aeruginosa infection to some extent in both models of the skin and acute lung infections, and the PIVpp itself caused no harmful effect on host tissues. However, since the degree to which LasA_pp alleviated the infection was very small compared to that expected from the degree to which LasA_pp inhibited the activity of purified LasA in vitro, we investigated how much LasA activity was inhibited when live P. aeruginosa cells were treated with LasA_pp. As a result, LasA activity was inhibited only to a very small extent compared to the in vitro result with the purified LasA. This demonstrates that when LasA_pp is directly applied to live P. aeruginosa cells, LasA_pp does not sufficiently inhibit the activity of LasA, and thus the effect of alleviating severity of infection is limited.

A Gram-negative, facultatively anaerobic, rod-shaped (1.4 ±0.46 μm × 0.53 ± 0.17 μm) and motile marine bacterium designated as MEBiC11861T was isolated from a marine algal debris collected from Kosrae, Federation State of Micronesia (162°57’23.1"E, 5°21’13.0"N). Based on the 16S rRNA gene sequence analysis strain MEBiC11861T identified as a novel species in the genus Nisaea, it showed high similarity to members of the genus Nisaea (97.0–98.4%). Strain MEBiC11861T was growing at 10–42℃ (optimum 26–29℃), at pH 4.0–8.5 (optimum pH 5.0) and with 0–10% (optimum 0.5%) NaCl. The C12:0 (5.6%), C16:0 (29.0%), C12:0 3-OH (4.3%), summed feature 3 (C16:1 ω7c and/or C16:1 ω6c; 9.9%), summed feature 8 (C18:1 ω7c and/or C18:1 ω6c; 31.2%), and C19:0 cyclo ω8c (10.6%) were determined to be as predominant cellular fatty acids. The DNA G + C content is 63.0 mol%. The major respiratory quinone is Q-10. Several phenotypic characteristics such as utilization of gluconate, malate, adipate, arabinose etc., DNA G + C ratio, cellular fatty acids composition, and growth range of pH and salinity differentiate strain MEBiC11861T from members of the genus Nisaea. On the basis of this polyphasic taxonomic data, strain MEBiC11861T should be classified as a novel species in the genus Nisaea and it is proposed as Nisaea acidiphila sp. nov. The type strain is MEBiC11861T (= KCCM 43219T = JCM 31589T). Emended description of the genus Nisaea Urios et al. 2008 and emendation of halassobaculum salexigens were also given.