Prospective role of indigenous Exiguobacterium profundum PT2 in arsenic biotransformation and biosorption by planktonic cultures and biofilms.

AIMS: The aim of this study was to analyse arsenic (As) transformation and biosorption by indigenous As-resistant bacteria both in planktonic and biofilm modes of growth. METHODS AND RESULTS: As-resistant bacteria were isolated from industrial waste water and strain PT2, and identified as Exiguobacterium profundum through 16S rRNA gene sequencing was selected for further study. As transformation and biosorption by E. profundumPT2 was determined by HPLC-ICP-MS analysis. Planktonic cultures reduced 3·73 mmol l-1 As5+ into As3+ from artificial waste water effluent after 48-h incubation. In case of biosorption, planktonic cultures and biofilms exhibited 25·2 and 29·4 mg g-1 biomass biosorption, respectively. As biosorption kinetics followed Freundlich isotherm and pseudo second-order model. Biofilm formation peaked after 3 days of incubation, and in the presence of As stress, biofilm formation was significantly affected in contrast to control (P < 0·05). Homogeneous nature of mature biofilms with an increased demand of nutrients was revealed by minimum roughness and maximum surface to biovolume ratio measured through CLSM analysis. CONCLUSION: Indigenous As-resistant E. profundumPT2 was found capable of As transformation and biosorption both in the form of planktonic cultures and biofilms. SIGNIFICANCE AND IMPACT OF THE STUDY: Indigenous biofilm forming E. profundum PT2 revealing As biosorption and biotransformation potential is presented an eco-friendly and cost-effective source for As remediation that can be implemented for waste water treatment.

Auxin production by plant associated bacteria: impact on endogenous IAA content and growth of Triticum aestivum L.

AIMS: The aim of this study was to investigate the potential of bacterial strains of Bacillus, Pseudomonas, Escherichia, Micrococcus and Staphylococcus genera associated with wild herbaceous flora to enhance endogenous indole-3-acetic acid (IAA) content and growth of Triticum aestivum var. Inqalab-91. METHODS AND RESULTS: Gas chromatography and mass spectrometric (GC-MS) analysis revealed that bacterial strains produced 0.6-8.22 microg IAA ml(-1) in the presence of L-tryptophan. Plant microbe experiments showed a significant positive correlation between auxin production by bacterial strains and endogenous IAA content of T. aestivum for GC-MS (r = 0.618; P = 0.05) and colorimetric analysis (r = 0.693; P = 0.01). Similarly, highly significant positive correlation for shoot length (r = 0.627; P = 0.01) and shoot fresh weight (r = 0.626; P = 0.01) was observed with auxin production under axenic conditions. Bacterial inoculations also enhanced shoot length (up to 29.16%), number of tillers (up to 97.35%), spike length (up to 25.20%) and seed weight (up to 13.70%) at final harvest. CONCLUSIONS: Bacterial strains have the ability to increase the endogenous IAA content and growth of T. aestivum var. Inqalab-91. SIGNIFICANCE AND IMPACT OF THE STUDY: Microbial strains of wild herbaceous flora can be effectively used to enhance the growth and yield of agronomically important crops.

Effect of biocides on biofilm bacteria from dental unit water lines.

Microbial biofilm formation in dental unit water lines (DUWL) is a phenomenon that has been recognized for nearly four decades. Water delivered by DUWL can harbor high numbers of bacteria, including opportunistic pathogens. Biofilms on tubing within DUWL may serve as a reservoir for these microorganisms and should therefore be controlled. In this study, the effects of eight biocides were monitored on DUWL biofilms individually and in combination by epifluorescence microscopy and total viable counts (TVC). The effects of sodium dodecyl sulphate (SDS), hydrogen peroxide (H2O2), sodium hypochlorite (NaOCl), phenol (Phe), Tween 20 (Tw 20), ethylenediaminetetraacetic acid (EDTA), chlorohexidine gluconate (CHX), and povidine iodine (PI) were tested on DUWL biofilms alone and in combination. PI was found to have negligible effects on biofilm removal either applied alone or in combined form with CHX. Applying all biocides simultaneously did not completely eliminate viable bacteria nor did they remove biofilm. Overall, when combined, the biocides performed better than singly applied products. The most effective biocides were NaOCl and Phe (both alone and in combination).

Vagal paragangliomas.

The management of vagal paragangliomas is extremely challenging. Treatment of these lesions must be tailored individually for each patient. The best treatment modality depends on the patient's age and health and the size and extent of the tumor. This article discusses clinical presentation, multicentric and malignant vagal paragangliomas, evaluation, embolization, surgical management, and special considerations in the management of vagal paragangliomas.

Paraganglioma surgery: complications and treatment.

Paragangliomas are vasculature in nature and are surrounded by vital neurovascular structures. The extirpation of these lesions requires careful preoperative evaluation, meticulous surgical technique, and the aid of experienced skull base surgical and rehabilitative teams. When surgery is performed in this way, complications can be minimized, and the function of the upper aerodigestive tract can be protected.

Growth stimulation of Triticum aestivum seedlings under Cr-stresses by non-rhizospheric pseudomonad strains.

Four chromium-resistant non-rhizospheric strains SPCr-1, SPCr-2, SPCr-3 and SPCr-4 (Pseudomonads), which were isolated from the effluents of an ICI paint factory and could tolerate 2-3 mg ml(-1) chromium in a minimal medium and 40 mg ml(-1) in a rich medium, were used to inoculate seeds of Triticum aestivum. Both inoculated and non-inoculated seeds were germinated and grown under different concentrations of chromium salts (K2CrO4, 0, 100, 250, 500; CrCl3, 0, 250, 500, 1000 microg ml(-1)). Germination and growth parameters were severely affected by chromium-salts. K2CrO4 had more drastic effects than CrCl3 treatments. Seedlings had a hard and brittle texture and showed symptoms of hypertrophy. Brown spots on leaves and stems were visible and the tips of leaves were bifurcated and curled. The root system was also impaired, ranging from a browning of the tip to complete destruction of cortical tissues. Under chromium-stress conditions, inoculated plants had significantly better germination and growth as compared to non-inoculated treatments. Bacterial growth enhancement of seedlings was associated with reduced chromium-uptake, increased auxin content and the formation of stress specific proteins. With bacterial inoculations, symptoms of chromium toxicity were reversed, especially at lower concentrations of chromium salts.

Effects of temperature and pH on conjugal transfer of zinc-resistant plasmids residing in Gram-negative bacteria isolated from industrial effluents.

Two zinc (Zn)-resistant strains, AnZn-1 and AnZn-2, which were resistant to ZnSO4 up to 12.5 mg ml(-1) were isolated from industrial effluents. Both were Gram-negative with motile cells. They exhibited tolerance to Ba2+, Ni+, Co2+, Mn2+, Cu2+, Fe2+, Ni2+, Cd2+, kanamycin, chloramphenicol, ampillicin and tetracycline, but were sensitive to Hg2+ and streptomycin. For AnZn-1 and AnZn-2, the optimum pH for growth was 7. Both were facultative anaerobes and had cytochrome oxidase and urease enzymes, while catalase was present only in AnZn-2. Both strains had the ability to hydrolyse gelatin, reduce nitrate, and yield acid from arabinose and rhamnose. The two strains shared maximum characters with Vibrionaceae. Each strain carries a single Zn-resistant conjugative plasmid. The plasmid residing in AnZn-1 (pSH1211) displayed a lower level of resistance than the plasmid of AnZn-2 (pSH1212). Both required a minimum of 24 h for mating and showed highest transfer frequency at 25 degrees C. pSH1211 preferred pH 7 and pSH1212 pH 8.5 for their transfer. Both plasmids, when allowed to mate with Escherichia coli at 25 degrees C, alkaline pH values of 8-8.5 (pSH1211) of pH 7.5 (pSH1212), showed increased transfer frequency.