Sulfobacillus disulfidooxidans sp. nov., a new acidophilic, disulfide-oxidizing, gram-positive, spore-forming bacterium.

An acidophilic, disulfide-oxidizing, mesophilic, aerobic bacterium was isolated from wastewater sludge. The new organism is a gram-positive sporulated rod. It can use elemental sulfur and pyrite as sole energy sources and grows on organic substrates such as glutamate and glucose. It also grows on the following organic sulfur substrates: oxidized and reduced glutathione, cysteine, cystine, and dithio(bis)benzothiazole and clearly shows a preference for disulfide bond-containing substrates. The optimal pH of growth is between 1.5 and 2.5, depending on the substrate used, and the growth temperature range varies from 4 to 40 degrees C, with an optimal value at 35 degrees C. The G + C chromosomal DNA content was measured at 53 +/- 1 mol%. Phylogenetic analysis of 16S genes coding for rRNA sequences places the new isolate in the genus Sulfobacillus. In addition, unique phenotypic and physiologic characteristics and DNA homology values assign the isolate to a new species in the genus. Therefore, this new isolate has been named Sulfobacillus disulfidooxidans and has been assigned ATCC number 51911.

Rotator cuff tear: clinical experience with sonographic detection.

Between June 1986 and April 1988, 86 sonographic examinations of the shoulder were performed on patients suspected of having rotator cuff tears. Major sonographic diagnostic criteria included (a) a well-defined discontinuity usually visible as a hypoechoic focus within the cuff, (b) nonvisualization of the cuff and (c) an echogenic focus within the cuff. Seventy-five patients underwent both sonography and arthrography. Compared with arthrography alone, ultrasound examinations enabled detection of 92% of rotator cuff tears (24 of 26 tears), with a specificity of 84% and a negative predictive value of 95%. Correlation was obtained in 30 of these patients who underwent surgery for rotator cuff tear or other soft-tissue abnormality. In this group, the sensitivity of sonography for detection of a tear was 93%, with a specificity of 73%, while for arthrography sensitivity was 87% and specificity was 100%. These data indicate that sonography is a useful, noninvasive screening procedure for patients suspected of having rotator cuff injury.

Heterogeneity in ampR-ampC gene interaction in Enterobacter cloacae.

The ampR gene and its regulation of AmpC beta-lactamase synthesis were investigated for Enterobacter cloacae 1194E, a wild-type strain producing a group A (pI 8.7) enzyme. Expression of the cloned E. cloacae 1194E ampR-ampC region was examined initially in Escherichia coli HB101. However, transformants showed only constitutive beta-lactamase expression. For study of enzyme expression in a more closely related host, the cloned E. cloacae 1194E ampR-ampC region was transformed into E. cloacae 55, a wild-type strain producing a group B (pI 7.8) enzyme. Results indicated a functional E. cloacae 1194E ampR gene that could not be transcomplemented by E. cloacae 55. A comparative analysis of ampR nucleotide and amino acid-sequence data from E. cloacae 1194E and E. cloacae MHN1 revealed related but divergent genes. Thermal induction studies of AmpC beta-lactamase also indicated a difference between E. cloacae 1194E and E. cloacae 55 in ampR-ampC interaction. Thus, it appears that, in at least some strains of Enterobacter, significant intraspecies divergence of ampR has occurred. This heterogeneity in ampR would not have been detected with beta-lactamase expression studies conducted exclusively in E. coli.

[Aerobic treatment of pig slurry: microbial aspects]. / Traitement aérobie du lisier de porc: aspects microbiens.

During the treatment of raw pig slurry by batch aerobic fermentation, the presence of surfaces for bacterial attachment resulted in a 1,000-fold increase in the microbial population. In the absence of such surfaces, a 65% reduction of the chemical oxygen demand (COD) of the manure was obtained after 168 h of aeration, whereas a value of 90% was observed in their presence. In the early stages of the treatment, during which the redox potential passed from a value characteristic of anaerobic conditions (-305 mV) to a stable value typical of aerobic conditions (+125 mV) some 120 h later, an amylolytic population dominated by Gram-negative bacteria (chiefly Acinetobacter calcoaceticus) developed; this was followed by a phase in which a proteolytic population tended to become dominant. Populations of some potentially pathogenic bacterial strains characteristic of the porcine intestinal flora declined noticeably during the treatment.

Cloning and characterization of chromosomally encoded cephalosporinase gene of Enterobacter cloacae.

The cephalosporinase gene, cpa, which codes for an inducible class I chromosomal beta-lactamase in Enterobacter cloacae was cloned on a fragment of 6.05 kilobase pairs inserted into plasmid pACYC184 and transferred into Escherichia coli HB101 recipient cells. The constructed hybrid plasmid, designated pGGQ101, carried a genomic fragment which retained its parental inducibility characteristics, although its expression level in transformed E. coli cells fell to 40-65% of its initial level in E. cloacae. The localization of the cpa gene on pGGQ101 plasmid was determined by Bal31 exonuclease deletion mapping and further confirmed by subcloning HindIII-AvaI restriction fragment on pMB9 plasmid vector. Labeling with [35S]methionine of pGGQ101 specified proteins in a minicell system showed that six or seven proteins are encoded by the insert. Two proteins with apparent molecular mass of 42 000 and 39 500 daltons, respectively, most probably represent the premature and mature cephalosporinase forms.

A feasibility study to determine if microbicidal activity can be measured in dexamethasone-treated macrophage cultures.

Dexamethasone action severely limits the ingestion of Saccharomyces cerevisiae in cultures of murine peritoneal macrophages. In spite of this inhibitory response, numbers of viable yeasts sufficient for microbicidal studies can be recovered shortly after their limited ingestion from lysed steroid-treated phagocytes.

Modulatory effects of heat-labile serum components on the inhibition of phagocytosis by dexamethasone in peritoneal macrophage cultures.

This investigation examined the effects of heat-labile serum substances on the suppression of yeast phagocytosis in dexamethasone-treated cultures of murine resident peritoneal macrophages. When 4-6 day old untreated control cultures were supplemented with either heat-inactivated (56 degrees C, 30 min) or intact (non-heat-inactivated) fetal bovine serum, more than 90% of the macrophage population ingested at least 1 yeast particle during 15 min phagocytosis assays. In cultures treated with 10(-6) M dexamethasone, approximately 30% of the macrophages were phagocytic. In contrast, approximately 70% of the steroid-treated population consisted of phagocytes in cultures supplemented with intact serum. Medium shift experiments demonstrated that the type of serum present during the 15 min yeast phagocytosis assays, but not the 4-6 day incubation periods, determined the size of the phagocytic subpopulations in the treated cultures. Whereas the majority of control phagocytes ingested more than 8 yeast particles, most dexamethasone-treated phagocytes ingested far fewer than 8 particles regardless of the size of the phagocytic subpopulations. In contrast to yeast, the ingestion of latex particles was inhibited to the same extent in dexamethasone-treated cultures that contained either heat-inactivated or intact serum. Thus, dexamethasone action impairs the ability of macrophages to accumulate yeast particles even though the phagocytic subpopulation is larger in treated cultures containing intact serum. This larger subpopulation may result from the activation of the alternative complement pathway by yeast during phagocytosis.

Inhibition of yeast phagocytosis by dexamethasone in macrophage cultures: reversibility of the effect and enhanced suppression in cultures of stimulated macrophages.

This investigation was initiated to characterize further the ability of 1 microM dexamethasone to suppress the ingestion of heat-killed Saccharomyces cerevisiae particles in cultures of murine resident peritoneal macrophages. Time course studies revealed that the inhibitory response required the continual presence of the steroid in the culture medium. In addition, increased inhibitory responses occurred after dexamethasone was supplied to previously untreated cultures of resident macrophages that became stimulated by differentiating in vitro. These findings indicate that glucocorticoids act directly on macrophages to decrease their phagocytic capacity, which in vivo would reduce host resistance.

Hydrolysis of Cefotaxime by a beta-lactamase from Bacteroides fragilis.

A beta-lactamase isolated from a strain of Bacteroides fragilis subsp. fragilis possessed hydrolytic activity toward cefotaxime. This antibiotic was degraded to a lower extent than was cephalothin, cephaloridine, and cefamandole, whereas cefoxitin remained unaffected by the enzyme. Kinetic parameters Vmax and Km for cefotaxime were calculated at 0.172 mumol/min and 1.1 X 10(-2) mM, respectively.

Ferrous iron oxidation and uranium extraction by Thiobacillus ferrooxidans.

The microbiological oxidation of ferrous iron in batch and continuous systems has been investigated in relation to uranium extraction from a low-grade ore by Thiobacillus ferrooxidans. The influence of the parameters, agitation, and aeration on oxygen saturation concentration, rate of oxygen mass transfer, and rate of ferrous iron oxidation was demonstrated. The kinetic values, Vmax and K were determined using an adapted Monod equation for different dilution rates and initial concentrations of ferrous iron. The power requirements for initial leaching conditions were also calculated. Uranium extraction as high as 68% has been realized during nine days of treatment. Regrinding the leach residue and its subsequent leaching yielded 87% uranium solubilization.

Base competition of DNA isolated from Thiobacillus ferrooxidans grown on different substrates.

The present study indicates some anomalies with respect to the DNA base composition of Thiobacillus ferrooxidans when it is cultured on different substrates. The % GC of the DNA of this bacterium has been calculated by three different methods (melting temperature, CsCl density gradient centrifugation and ultra-violet absorbancy ratios) using Escherichia coli and Rhodospirillum rubrum as references. The main values for T. ferrooxidans grown on ferrous iron, chalcopyrite and lead sulfide concentrates were calculated to be 56.0, 60.1 and 54.4% GC respectively. Although these large differences are not completely understood, an attempt has been made to explain this phenomenon.

[Ferrous ion oxidation and uranium solubilization from a lowgrade ore by "Thiobacillus ferrooxidans" (author's transl)]. / Oxydation de l'ion ferreux et mise en solution de l'uranium d'un mineral par Thiobacillus ferrooxidans

The microbiological oxidation of ferrous ion and the extraction of uranium from a low-grade ore has been studied using an adapted strain of Thiobacillus ferrooxidans. The effect of temperature, pH, volumetric oxygen transfer coefficient, K1a, and aeration number, Ia, on the activity of the microorganism has been determined. The activation energy for ferrous iron oxidation was calculated to be - 13.9 +/- 0.1 kcal/mole and inactivation (thermal death of bacteria) 53.3 +/- 0.2 kcal/mole. Temperature coefficient, Q10, was estimated to be 1.8. Uranium extraction varied between 80 and 100%.

Thiobacillus acidophilus sp. nov.; isolation and some physiological characteristics.

After a brief exposition to glucose, Thiobacillus acidophilus was isolated from a culture of iron-grown T. ferrooxidans. Physicochemical analysis of its DNA showed a G+C content of 62.9-63.2%. The new isolate grows best at 25-30 degrees C and at pH 3.0. Growth is possible between pH 1.5 and 6.0. Thiobacillus acidophilus is apparently strictly aerobic. Ammonium salts are the only suitable source of nitrogen. The bacterium is a facultative autotroph. In addition to elemental sulfur, it obtains energy from organic compounds such as D-glucose, D-galactose, D-fructose, D-mannitol, D-xylose, D-ribose, D-arabinose, L-arabinose, sucrose, sodium citrate, malic acid,dl-aspartic acid, and dl-glutamic acid. Thiobacillus acidophilus possesses the key enzymes of the tricarboxylic acid (TCA) cycle including NAD-and NADP-linked isocitric dehydrogenase and alpha-ketoglutarate dehydrogenase, and the key enzymes of the hexose monophosphate pathway (glucose-6-phosphate and 6-phosphogluconate dehydrogenase, and fructose 1,6-diphosphate aldolase). NADH oxidase has been found in particulate fraction of extracts. Rhodanese and thiosulfate oxidase have also been detected.

Base composition of deoxyribonucleic acid isolated from Athiorhodaceae.

Guanine plus cytosine content of deoxyribonucleic acid ranged from 60.5 to 65.0% for five Rhodospirillum species and from 64.4 to 70.3% for six Rhodopseudomonas species. These values were compared to those of two Hyphomicrobiaceae and two hydrogen-oxidizing bacteria.