Genome sequences of seven bacterial isolates collected from soil as part of a microbiology lab course.

Soil is a source for diverse microbes that possess useful biotechnological capabilities. Here, we report the genome sequences of seven bacterial isolates from the species Exiguobacterium acetylicum, Rossellomorea marisflavi, Delftia acidovorans, Pseudomonas aeruginosa, Bacillus sp., and Bacillus toyonensis (two isolates) cultured from Dallas/Fort Worth metroplex soil samples.

Enzymatic assay of D-mannose from urine.

AIM: Urinary tract infections (UTIs) are increasingly antibiotic resistant, and alternate or adjunct therapies are urgently needed. Several studies suggest that D-mannose ingestion and a hypothesized increase in urinary D-mannose reduce UTI frequency. Our goal was to develop a reliable assay for urinary D-mannose, which is needed to assess the effects of supplemental D-mannose on urinary D-mannose and UTIs. RESULTS: We developed an enzymatic assay for D-mannose in urine. Hexoses in urine were phosphorylated, sequentially isomerized and oxidized, and the increases in reduced NADPH were measured in a spectrophotometer. Urinary mannose from ten volunteers was well above the detection limit and ranged from 8 to 700 µM. CONCLUSION: A rapid, reliable, and sensitive assay was developed, readily detected urinary D-mannose, and is adaptable to high-throughput analysis. If urinary D-mannose is shown to correlate with susceptibility to UTIs, then the assay could assess susceptibility to UTIs and direct mannose therapy.

Anaerobic Cysteine Degradation and Potential Metabolic Coordination in Salmonella enterica and Escherichia coli.

Salmonella enterica has two CyuR-activated enzymes that degrade cysteine, i.e., the aerobic CdsH and an unidentified anaerobic enzyme; Escherichia coli has only the latter. To identify the anaerobic enzyme, transcript profiling was performed for E. coli without cyuR and with overexpressed cyuR Thirty-seven genes showed at least 5-fold changes in expression, and the cyuPA (formerly yhaOM) operon showed the greatest difference. Homology suggested that CyuP and CyuA represent a cysteine transporter and an iron-sulfur-containing cysteine desulfidase, respectively. E. coli and S. enterica ΔcyuA mutants grown with cysteine generated substantially less sulfide and had lower growth yields. Oxygen affected the CyuR-dependent genes reciprocally; cyuP-lacZ expression was greater anaerobically, whereas cdsH-lacZ expression was greater aerobically. In E. coli and S. enterica, anaerobic cyuP expression required cyuR and cysteine and was induced by l-cysteine, d-cysteine, and a few sulfur-containing compounds. Loss of either CyuA or RidA, both of which contribute to cysteine degradation to pyruvate, increased cyuP-lacZ expression, which suggests that CyuA modulates intracellular cysteine concentrations. Phylogenetic analysis showed that CyuA homologs are present in obligate and facultative anaerobes, confirming an anaerobic function, and in archaeal methanogens and bacterial acetogens, suggesting an ancient origin. Our results show that CyuA is the major anaerobic cysteine-catabolizing enzyme in both E. coli and S. enterica, and it is proposed that anaerobic cysteine catabolism can contribute to coordination of sulfur assimilation and amino acid synthesis.IMPORTANCE Sulfur-containing compounds such as cysteine and sulfide are essential and reactive metabolites. Exogenous sulfur-containing compounds can alter the thiol landscape and intracellular redox reactions and are known to affect several cellular processes, including swarming motility, antibiotic sensitivity, and biofilm formation. Cysteine inhibits several enzymes of amino acid synthesis; therefore, increasing cysteine concentrations could increase the levels of the inhibited enzymes. This inhibition implies that control of intracellular cysteine levels, which is the immediate product of sulfide assimilation, can affect several pathways and coordinate metabolism. For these and other reasons, cysteine and sulfide concentrations must be controlled, and this work shows that cysteine catabolism contributes to this control.