Comparison of fluorinated polymers against stainless steel, glass and polypropylene in microbial biofilm adherence and removal

Biofilm formation is a long-standing problem in ultrapure water and bioprocess fluid transport lines. The standard materials used in these applications (316L stainless steel, polypropylene and glass) have long been known to be good surfaces for the attachment of bacteria and other biological materials. To compare the relative tenacity of biofilms grown on materials used in manufacturing processes, a model system for biofilm attachment was constructed that approximates the conditions in industrial process systems. New fluorinated polymers were compared to the above materials by evaluating the surface area coverage of bacterial populations on materials before and after mild chemical treatment. In addition, contact angle studies compared the relative hydrophobicity of surfaces to suspensions of bacteria in growth media, and scanning electron microscopy and atomic force microscopy studies were used to characterize surface smoothness and surface defects. Biofilm adherence to polymer-based substrata was determined to be a function of both surface finish and surface chemistry. Specifically, materials that are less chemically reactive, as indicated by higher contact angle, can have rougher surface finishes and still be amenable to biofilm removal. Received 20 March 1997/ Accepted in revised form 15 July 1997     

Proton nuclear magnetic resonance saturation transfer studies of coenzyme binding to Lactobacillus casei dihydrofolate reductase

The chemical shifts of all the aromatic proton and anomeric proton resonances of NADP+, NADPH, and several structural analogues have been determined in their complexes with Lactobacillus casei dihydrofolate reductase by double-resonance (saturation transfer) experiments. The binding of NADP+ to the enzyme leads to large (0.9-1.6 ppm) downfield shifts of all the nicotinamide proton resonances and somewhat smaller upfield shifts of the adenine proton resonance. The latter signals show very similar chemical shifts in the binary and ternary complexes of NADP+ and the binary complexes of several other coenzymes, suggesting that the environment of the adenine ring is similar in all cases. In contrast, the nicotinamide proton resonances show much greater variability in position from one complex to another. The data show that the environments of the nicotinamide rings of NADP+, NADPH, and the thionicotinamide and acetylpyridine analogues of NADP+ in their binary complexes with the enzyme are quite markedly different from one another. Addition of folate or methotrexate to the binary complex has only modest effects on the nicotinamide ring of NADP+, but trimethoprim produces a substantial change in its environment. The dissociation rate constant of NADP+ from a number of complexes was also determined by saturation transfer.     

EPR of Cu Prion Protein Constructs at 2 GHz Using the g⊥ Region to Characterize Nitrogen Ligation

A double octarepeat prion protein construct, which has two histidines, mixed with copper sulfate in a 3:2 molar ratio provides at most three imidazole ligands to each copper ion to form a square-planar Cu²⁺ complex. This work is concerned with identification of the fourth ligand. A new (to our knowledge) electron paramagnetic resonance method based on analysis of the intense features of the electron paramagnetic resonance spectrum in the g_⊥ region at 2 GHz is introduced to distinguish between three and four nitrogen ligands. The methodology was established by studies of a model system consisting of histidine imidazole ligation to Cu²⁺. In this spectral region at 2 GHz (S-band), g-strain and broadening from the possible rhombic character of the Zeeman interaction are small. The most intense line is identified with the M_I = +1/2 extra absorption peak. Spectral simulation demonstrated that this peak is insensitive to cupric A_x and A_y hyperfine interaction. The spectral region to the high-field side of this peak is uncluttered and suitable for analysis of nitrogen superhyperfine couplings to determine the number of nitrogens. The spectral region to the low-field side of the intense extra absorption peak in the g_⊥ part of the spectrum is sensitive to the rhombic distortion parameters A_x and A_y. Application of the method to the prion protein system indicates that two species are present and that the dominant species contains four nitrogen ligands. A new loop-gap microwave resonator is described that contains ∼1 mL of frozen sample.     

Taxonomy of the Lyme disease spirochetes.

Morphology, physiology, and DNA nucleotide composition of Lyme disease spirochetes, Borrelia, Treponema, and Leptospira were compared. Morphologically, Lyme disease spirochetes resemble Borrelia. They lack cytoplasmic tubules present in Treponema, and have more than one periplasmic flagellum per cell end and lack the tight coiling which are characteristic of Leptospira. Lyme disease spirochetes are also similar to Borrelia in being microaerophilic, catalase-negative bacteria. They utilize carbohydrates such as glucose as their major carbon and energy sources and produce lactic acid. Long-chain fatty acids are not degraded but are incorporated unaltered into cellular lipids. The diamino amino acid present in the peptidoglycan is ornithine. The mole % guanine plus cytosine values for Lyme disease spirochete DNA were 27.3-30.5 percent. These values are similar to the 28.0-30.5 percent for the Borrelia but differed from the values of 35.3-53 percent for Treponema and Leptospira. DNA reannealing studies demonstrated that Lyme disease spirochetes represent a new species of Borrelia, exhibiting a 31-59 percent DNA homology with the three species of North American borreliae. In addition, these studies showed that the three Lyme disease spirochetes comprise a single species with DNA homologies ranging from 76-100 percent. The three North American borreliae also constitute a single species, displaying DNA homologies of 75-95 percent. Lyme disease spirochetes and Borrelia exhibited little or no DNA homology (0-2 percent) with the Treponema or Leptospira. Plasmids were present in the three Lyme disease spirochetes and the three North American borreliae.     

The generaAniptodera, Halosarpheia, Nais andPhaeonectriella from freshwater habitats

The generic concepts inAniptodera, Halosarpheia, Nais andPhaeonectriella are discussed and those species occurring in freshwater are described, some with illustrations. Five new species:Aniptodera lignicola, A. mauritaniensis, A. megalospora, A. palmicola, Phaeonectriella appendiculata are also described. A key to the freshwater species in the above genera and a synoptic diagram of their ascospores are provided.     

Cryptophiale sphaerospora sp. nov. occurring onJanetia synnematosa

Cryptophiale sphaerospora sp. nov. is described and illustrated based on a single collection attached to a synnematous fungus,Janetia synnematosa, from a dead bamboo culm. It differs from other species ofCryptophiala in having spherical to subspherical conidia and a cerebroid layer of phialides. The overall morohology of this species is smaller than that of previously described species.     

Arecophila bambusae sp. nov. andA. coronata comb. nov., from dead culms of bamboo

A new species ofArecophila and a species previously known asAmphisphaeria coronata are described and illustrated from dead culms of bamboo.Arecophila bambusae sp. nov. is distinct in the genus in having ellipsoidal ascospores with slightly round ends, and asci with a narrow subapical ring.Arecophila coronata comb. nov. has asci with a wedgeshaped apical ring and weakly striated ascospores enclosed in wide mucilaginous sheath.