In Bacillus subtilis, the DL-endopeptidase LytE is responsible for lateral peptidoglycan hydrolysis during cell elongation. We found that I -dependent transcription of lytE is considerably enhanced in a strain with a mutation in ltaS, which encodes a major lipoteichoic acid (LTA) synthase. Similar enhancements were observed in mutants that affect the glycolipid anchor and wall teichoic acid (WTA) synthetic pathways. Immunofluorescence microscopy revealed that the LytE foci were considerably increased in these mutants. The localization patterns of LytE on the sidewalls appeared to be helix-like in LTA-defective or WTAreduced cells and evenly distributed on WTA-depleted or -defective cell surfaces. These results strongly suggested that LTA and WTA affect both I -dependent expression and localization of LytE. Interestingly, increased LytE localization along the sidewall in the ltaS mutant largely occurred in an MreBH-independent manner. Moreover, we found that cell surface decorations with LTA and WTA are gradually reduced at increased culture temperatures and that LTA rather than WTA on the cell surface is reduced at high temperatures. In contrast, the amount of LytE on the cell surface gradually increased under heat stress conditions. Taken together, these results indicated that reductions in these anionic polymers at high temperatures might give rise to increases in SigI-dependent expression and cell surface localization of LytE at high temperatures. IMPORTANCEThe bacterial cell wall is required for maintaining cell shape and bearing environmental stresses. The Gram-positive cell wall consists of mesh-like peptidoglycan and covalently linked wall teichoic acid and lipoteichoic acid polymers. It is important to determine if these anionic polymers are required for proliferation and environmental adaptation. Here, we demonstrated that these polymers affect the expression and localization of a peptidoglycan hydrolase LytE required for lateral cell wall elongation. Moreover, we found that cell surface decorations with teichoic acid polymers are substantially decreased at high temperatures and that the peptidoglycan hydrolase is consequently increased. These findings suggest that teichoic acid polymers control lateral peptidoglycan hydrolysis by LytE, and bacteria drastically change their cell wall content to adapt to their environment.

Abstract:Evaporation from the forest floor (Ef ) of a secondary broad-leaved forest was monitored for 1 year at 30 min intervals using a closed chamber system. The diurnal and seasonal variation of Ef and forest structure were analysed for days undisturbed by rainfall. The diurnal change in Ef reached a maximum at about 14 : 00 and gradually decreased towards midnight along with the vapour pressure deficit (D). Although Ef comprised about 20% of evapotranspiration from the dry canopy (Et ), it had only a small influence on diurnal evaporation efficiency (ˇ) characteristics above the canopy because its diurnal range was much smaller than that of Et. Although leaf emergence and leaf fall clearly affected available energy (Ae) beneath the canopy, the influence was not clear with Ef. In contrast, seasonal variation in Ef was strongly correlated with D and Ae above the canopy, and the determination coefficient (R 2 ) changed with the Bowen ratio (B). At night, Et was almost equal to Ef when the friction velocity (u Ł ) ranged between 0Ð2 and 0Ð4 m s 1 . The ratio of Ef to Et was exponentially correlated with leaf area index (LAI ) when the soil was not dry. The ratio of Ef to Et was mainly influenced by LAI and soil moisture, but the existence of understory vegetation did not have a strong influence.

The adsorption behaviors of the rare earth metal ions onto freeze-dried powders of genetically engineered microbial strains were compared. Cell powders obtained from four kinds of strains, Bacillus subtilis 168 wild type (WT), lipoteichoic acid-defective (ΔLTA), wall teichoic acid-defective (ΔWTA), and cell wall hydrolases-defective (EFKYOJLp) strains, were used as an adsorbent of the rare earth metal ions at pH 3. The adsorption ability of the rare earth metal ions was in the order of EFKYOJLp > WT > ΔLTA > ΔWTA. The order was the same as the order of the phosphorus quantity of the strains. This result indicates that the main adsorption sites for the ions are the phosphate groups and the teichoic acids, LTA and WTA, that contribute to the adsorption of the rare earth metal ions onto the cell walls. The contribution of WTA was clearly greater than that of LTA. Each microbial powder was added to a solution containing 16 kinds of rare earth metal ions, and the removals (%) of each rare earth metal ion were obtained. The scandium ion showed the highest removal (%), while that of the lanthanum ion was the lowest for all the microbial powders. Differences in the distribution coefficients between the kinds of lanthanide ions by the EFKYOJLp and ΔWTA powders were greater than those of the other strains. Therefore, the EFKYOJLp and ΔWTA powders could be applicable for the selective extraction of the lanthanide ions. The ΔLTA powder coagulated by mixing with a rare earth metal ion, although no sedimentation of the WT or ΔWTA powder with a rare earth metal ion was observed under the same conditions. The EFKYOJLp powder was also coagulated, but its flocculating activity was lower than that of ΔLTA. The ΔLTA and EFKYOJLp powders have a long shape compared to those of the WT or ΔWTA strain. The shapes of the cells will play an important role in the sedimentation of the microbial powders with rare earth metal ions. As the results, three kinds of the genetically engineered microbial powders revealed unique adsorption behaviors of the rare earth metal ions.

B acillus subtilis is a gram-positive, rod-shaped, spore-forming bacterium temporarily present in the human gastrointestinal tract (1). The presence of B. subtilis in clinical specimens indicates contamination, but rare cases of bacteremia have been reported in Japan (2). Previous reports have attributed bacteremia in Japan to gastrointestinal origin but of

Wall teichoic acids (WTAs) are anionic polymers that are covalently linked to peptidoglycan and play important roles in cell shape determination, cell division, autolysis, pathogenesis and antibiotic resistance in Gram-positive bacteria. In Bacillus subtilis, WTA is synthesized in the cytoplasm and translocated by an ABC transporter, TagGH. In this study, we found that the transmembrane segment of TagH is required for WTA transport under high temperatures. Cells expressing TagH302-FL (a construct fused to the 6×FLAG tag after the transmembrane segment, which lacks the C-terminal extracellular domain) grew normally at high temperatures, similar to those expressing the full-length TagH-FL fusion. In contrast, cells expressing TagH275-FL, which lacks both the transmembrane segment and the extracellular domain, exhibited a temperature-sensitive phenotype at temperatures above 49 °C and a growth defect at 50 °C. Interestingly, this growth defect was dissolved by an additional incubation at 37 °C. A similar temperature-sensitive phenotype was observed in cells expressing an N-terminal 6×FLAG tag fusion of TagH275. Immunofluorescence microscopy (IFM) indicated that TagG and TagH are localized on the cytoplasmic membrane in a patch-like manner. In addition, the C-terminal-truncated forms, TagH275-FL and TagH302-FL, were localized in similar patch-like patterns at 37 °C; only foci for TagH275-FL were remarkably reduced at high temperatures. Moreover, cell surface decoration with WTA was considerably reduced in cells harbouring TagH275-FL at high temperature, supporting the results of IFM observation. These results suggest that the transmembrane segment of TagH plays an important role in WTA export at high temperatures.