Impact of pH regulation on multicopper oxidase production and swarming motility in the bacterium Proteus hauseri ZMd44.

Proteus hauseri ZMd44, a biodecolorizing bacterium, has been known to produce electricity and multicopper oxidase (Mco-laccase) under copper induction. However, optimization and regulation of production have not been explored. This study is the first attempt to evaluate several parameters on biomass and Mco-laccase production of P. hauseri ZMd44. Through orthogonal experiments with Taguchi's L9, it was found that P. hauseri ZMd44 was sensitive to pH value. The cells grew relatively quickly at pH 7, thus the biomass and Mco-laccase production reached 1.66 g/L and 1043.6 U/L, respectively. Higher pH values also influenced the swarming motility, which is an important characteristic of P. hauseri ZMd44 that affects urinary tract infection. The swarming circle and the diameter of the swarm, represented by the motility velocity, were found to be more controlled after 24 h of growth at pH 6. The swarming ability of P. hauseri was completely inhibited by the addition of 3 mM copper or zinc ions. Therefore, the Mco-laccase and swarming motility could be controlled by regulating pH and ion content.

Copper response of Proteus hauseri based on proteomic and genetic expression and cell morphology analyses.

The copper response of Proteus hauseri ZMd44 was determined using one-dimensional (1D) gel electrophoresis coupled with MALDI-TOF-TOF mass spectrometry for a similarity analysis of proteins isolated from P. hauseri ZMd44 cultured in CuSO4-bearing LB medium. Candidate proteins identified as a copper-transporting P-type ATPase (CTPP), phosphoenolpyruvate carboxykinase (PEPCK), flagellin (Fla), and outer membrane proteins (Omps) were the major copper-associated proteins in P. hauseri. In a comparative analysis of subcellular (i.e., periplasmic, intracellular, and inner membranes) and cellular debris, proteomics analysis revealed a distinct differential expression of proteins in P. hauseri with and without copper ion exposure. These findings were consistent with the transcription level dynamics determined using quantitative real-time PCR. Based on a genetic cluster analysis of copper-associated proteins from P. hauseri, Fla and one of the Omps showed greater diversity in their protein sequences compared to those of other Proteus species. Transmission electron microscopy (TEM) and the observed growth on LB agar plates showed that the swarming motility of cells was significantly suppressed and inhibited upon Cu(II) exposure. Thus, copper stress could have important therapeutic significance due to the loss of swarming motility capacity in P. hauseri, which causes urinary tract infections.

Assessment upon azo dye decolorization and bioelectricity generation by Proteus hauseri.

This study explored dye decolorization and bioelectricity generation of indigenous Proteus hauseri ZMd44 for dye-bearing wastewater treatment. Chemical structures of azo dyes apparently affected the performance of dye biodecolorization. Additions of diazo dye C.I. reactive blue 160 (RBu160) stimulated simultaneous dye decolorization and bioelectricity generation of ZMd44 in single chamber microbial fuel cells (MFCs). However, high-level additions of RBu160 repressed capabilities of power production in MFC due to competition of electrons used for reductive decolorization. Decolorized intermediates of RBu160-phenyl methadiamine and 5-sulfoanthranilic acid as electron shuttles might mediate electron transport for current generation in MFC.

A novel glutamate-dependent acid resistance among strains belonging to the Proteeae tribe of Enterobacteriaceae.

Morganella, Providencia and Proteus strains were capable of surviving pH 2.0 for 1 h if glutamate was present. These strains did not have glutamic acid decarboxylase activity and the gadAB genes were not detected in any of these bacteria. When exposed to pH 2.0 acid shocks, the survival rate of these bacteria was significantly increased with glutamate concentrations as low as 0.3 mM in the acid media. Escherichia coli cells incubated at pH 3.4 consumed four times more glutamate and produced at least 7-fold more gamma-amino butyric acid than Morganella, Providencia and Proteus strains. These results indicate that strains belonging to the Proteeae tribe might have novel glutamate dependent acid-resistance mechanisms.

Rapid agglutination testing in an ultrasonic standing wave.

The time taken to perform diagnostic agglutination tests can be significantly reduced by applying an ultrasonic standing wave field to a droplet of reactants held in a capillary tube. Avian erythrocytes, bacteria and latex particles from commercially available test kits were agglutinated in 15 s, 5 min, and 1 min respectively. These times compare favourably with the times of 30 min, 4 h, and 8 min required for agglutination by the methods prescribed for the respective kits. No loss in sensitivity or specificity was observed with the ultrasonic method. A multi-test procedure is also described whereby a series of five droplets loaded in a single capillary can be tested in less than 4 min by drawing the capillary along the axis of the ultrasonic field of a ring transducer.

[Morphological studies on antibacterial activities of cefotiam (author's transl)].

1. Cefotiam was demonstrated to be more potent than cefazolin in its antibacterial activities against clinical isolates of E. coli, Klebsiella, Serratia, Proteus mirabilis, Proteus morganii and Proteus inconstans. MICs of cefotiam with 10(6) cells/ml inoculum size were considerably lower than those with 10(8) cells/ml. 2. Organisms lysed when exposed to cefotiam at concentrations higher than the MICs with 10(8) cells/ml. Morphological changes of organisms into filament occurred even at concentrations lower than the MICs with 10(6) cells/ml. This indicates that cefotiam is incorporated into organisms at remarkably low concentrations and exerts its antibacterial activities. 3. Cefotiam showed a high affinity for penicillin-binding proteins (PBP) 1A, 1Bs and 3. The formation of filament at low concentrations of cefotiam is possibly attributable to the high affinity of cefotiam for PBP 3 in addition to its high permeability through outer cell membrane. 4. As the antibacterial activities of cefotiam are displayed at lower concentrations, it is reasonable to consider that doses of cefotiam on clinical use can be reduced in comparison with those of conventional cephalosporins.

[Expansion phenomena of Proteus cultures. I. The swarming expansion (author's transl)]. / Expansionserscheinungen der Proteuskulturen. I. Die Schwärmexpansion

The expansion of Proteus cultures on nutrient agar plates is in general attributed to negative chemotaxis with regard to a metabolic product of the culture itself. The initial latency of several hours is assumed to be the time necessary for the production and imbibition of the nutrient with the incriminated metabolite. In the present paper it will be shown that independent of this delayed expansion (expansion with initial latency) there also exists an immediate expansion that takes place when the seeded material is young (less than 12-24 hours) and rich in invasive filaments. The reaction also occurs after washing the seeded material in fresh broth. It is therefore independent of the presence of a metabolite whose production and diffusion in the nutrient substrate would have necessitated some time. It is not a question of reaction to a chemical substance but, as demonstrated experimentally, of a response to tactile stimuli. Marked thigmotaxis induced centrifugal penetration of invading filaments at the edge of the seeded droplet, between the superficial film of the suspension fluid and the surface of the nutrient agar. Heading towards the narrowest capillary spaces, groups of bacilli form, immediately after seeding, protrusions that emboss the outer contour of the droplet ("protuberances" Fig. 2, 3, 15). These protuberances continue outwards until they detach themselves from the central agglomeration. The independent bacterial "shoals" (Fig. 5, 6, 10) swarm chaotically around the seeded droplet. The total lack of orientation has been checked by numerous procedures used for recording the direction of a movement; one of this consists in recording the pathways in a latex film on agar plates (Fig. 1). This swarming phase may last 15 to 30 minutes. As the random movements in a contrary direction compensate one another, the chaotic migration of the microbial shoals would contribute little to expansion of the colony, if gradual disruption of the bacterial groups would not interfere in the meantime. Isolated individuals detached from the shoals become immobile from the moment in which they separate from the bacterial group they belonged to ("immunobilization reaction"). Therefore the migrating shoals function as organs of dissemination of the bacteria in the surrounding medium (Fig. 11). (see article).

Ultrastructure of the cell wall and cytoplasmic membrane of gram-negative bacteria with different fixation techniques.

The ultrastructure of the cytoplasmic membrane and cell wall of two strains of Escherichia coli, Proteus morganii, P. vulgaris, Acinetobacter anitratum, Moraxella lacunata, Erwinia amylovora, Acinetobacter sp., and of a plant pathogen, unclassified gram-negative, fixed by the Ryter-Kellenberger procedure, was found to be significantly affected by the use or omission of the uranyl postfixation included in that procedure, and by the presence or absence of calcium in the OsO(4) fixative. The omission of the uranyl treatment results in a less clear profile of both the outer membrane of the cell wall and of the cytoplasmic membrane. The observation of these two membranes is further limited when both uranyl and calcium are omitted. The R-layer and the material covering the surface of the cell wall appear more distinct when the uranyl postfixation is not used. Evidence is given suggesting that the influence of uranyl and calcium ions on the appearance of the outer and cytoplasmic membranes would be primarily due to their action as fixatives, whereas the influence of uranyl on the appearance of the R-layer would be due to a direct action on the peptidoglycan component of this layer. When uranyl acetate is used as a section stain after the embedding in plastic, it improves the observation of the R-layer. In this case, a well contrasted R-layer is consistently observed in all strains studied, provided that the postfixation has been omitted. The frequent difficulty in clearly observing the R-layer in many published micrographs probably results from the common use of uranyl postfixation.

Regulation of flagellar morphogenesis by temperature: involvement of the bacterial cell surface in the synthesis of flagellin and the flagellum.

When cells of Proteus vulgaris were transferred from 37 to 42 C, a temperature at which they continue to grow almost optimally, they ceased to form flagella after approximately one generation time. This failure was due to a lesion in the flagellin-synthesizing process rather than the inability of these cells to assemble the organelle from constituents once formed. After transfer back to 37 C, these cells regained their ability to synthesize flagellin and form flagella, after one generation. When added during this period, chloramphenicol, rifampin, or penicillin prevented the synthesis of flagellin. The regeneration of the organelle at 37 C, then, requires growth for one generation, a period during which not only ribonucleic acid and protein synthesis, but also the presence of an intact cell envelope or concurrent synthesis of cell wall, are required.