Polluted sites often contain both heavy metals and organic xenobiotic contaminants. This warrants the use of either a great number of bacterial degraders or bacteria having the ability to detoxify several toxicants simultaneously. In this research, the ability of a molybdenum-reducing (Mo-reducing) bacterium isolated from contaminated soil to decolorize various phenolics independent of Mo reduction was screened. Studies showed that this bacterium was able to grow on 4-nonylphenol and reduced molybdate to Mo-blue. The optimal condition for this activity was pH between 6.3 and 6.8 and temperature of 34EC. Glucose proved to be the best electron donor for supporting molybdate reduction followed by galactose, fructose, and citrate in descending order. Other requirements included a phosphate concentration between 2.5 mM and 7.5 mM and a molybdate concentration between 20 and 30 mM. The absorption spectrum of the Mo-blue produced was similar to numerous previously described Mo-reducing bacteria, closely resembling a spectrum of the reduced phosphomolybdate. Mo reduction was inhibited by mercury (II), silver (I), copper (II), cadmium (II), and chromium (VI) at 2 ppm by 79.6%, 64.2%, 51.3%, 28.1%, and 25.0%, respectively. The biochemical analysis resulted in a tentative identification of the bacterium as Pseudomonas aeruginosa strain Amr-11. The ability of this bacterium to detoxify Mo and grow on nonylphenol makes this bacterium an important tool for bioremediation.

The objectives of this work were to isolate and characterise a heavy metal-reducing bacterium with the capability to degrade another xenobiotic; an organic pollutant. Six molybdenum-reducing bacteria from soil that can reduce sodium molybdate into the colloidal molybdenum blue (Mo-blue) were isolated. One of these isolates identified as Pseudomonas putida strain Egypt-15 was capable of growing on PEG 4000. The optimal conditions for Mo-blue production were 34 °C, pH 6.5, 20 mM molybdate, and glucose as the electron donor. The optimum concentration supporting the growth on PEG 4000 was between 600 and 800 mgL-1. PEG degradation showed a lag period of about two days and 75 % degradation of PEG 4000 was achieved on day six at 800 mgL-1. Growth on PEG 4000 at 800 mgL-1 modelled according to the modified Gompertz model gave a maximum specific growth rate of 2.216 d-1 and a lag period of 1.45 days. Growth on PEG was optimum at 30 °C and pH 7.5. The dual ability of this bacterium to detoxify molybdenum and degrade PEG is novel and will be very useful for bioremediation.

Molybdenum is a pollutant that shows toxicity to spermatogenesis while polyethylene glycols (PEG) are used predominantly in detergents. The pollution of molybdenum and PEGs are reported worldwide. We have isolated ten molybdenum-reducing bacterial isolates from soil that can reduce molybdenum (sodium molybdate) into the colloidal molybdenum blue (Mo-blue). The screening of these isolates for PEG-degrading ability showed that one isolate was capable to utilize PEG 200, 300 and 600 for optimal conditions were pHs between 5.5 and 8.0, temperatures between 30 and 37 oC, phosphate at 5 mM, molybdate between 10 and 30 mM, and glucose as the electron donor. Biochemical analysis of the bacterium identifies it as Escherichia coli strain Amr-13. Growth was best supported by all PEGs at concentrations of between 600 and 1,000 mg/L. A complete degradation for PEG 200 and PEG 300 at 1,000 mg/L was observed on day four and five, respectively, while nearly 90% of PEG 600 was degraded on day six. The growth of this bacterium on these PEGs was modelled using the modified Gompertz model, and produced growth parameters values, which were maximum specific growth rates of 1.51, 1.45 and 1.18 d-1 and lag periods of 0.53, 0.87 and 1.02 day for PEG 200, PEG 300 and PEG 600, respectively. PEG 200 was the most preferred substrate for this bacterium, while PEG 600 was the least preferred.

E XTENDED-spectrum β-lactamase (ESBL) producing Klebsiella pneumoniae strains can present resistance to many antibiotic groups due to resistant genes. This study conducted to detect and identify multi-drug resistant (MDR), ESBL producing K. pneumoniae strains from different clinical samples with detection and sequencing of both Temoneira (TEM) and sulfhydryl variable (SHV) genes and using Glycyrrhizic acid nanoparticle as an antimicrobial agent for ESBL producing K. pneumoniae strains. One hundred and fifty clinical specimens were processed. ESBL producing K. pneumoniae strains were detected by double disk synergy test. TEM and SHV genes responsible for MDR in K. pneumoniae were detected by polymerase chain reaction (PCR) and sequence alignment was done using DNA sequencing. The effect of different concentrations of Nano Glycyrrhizic acid was determined. K. pneumoniae was detected in 53.3% of the total collected samples (80/150). Seventy one percent (57/80) of them were found to be multi-drug resistant strains and 63% (36/57) also found to contain the ESBL enzymes. Males were highly infected than females. TEM gene was detected in 52.8% of the ESBL isolates while SHV gene was detected in 72.2%. Twenty Five percent of the ESBL producing K. pneumoniae was found to contain both TEM and SHV genes. Nucleic acid sequence alignment of both genes showed some mutations. Chloramphenicol was found to be the drug of choice to overcome ESBL producing K. pneumoniae with inhibition of 97.2%. The antibacterial activity of Nano Glycyrrhizic acid revealed that 10µg/ml was found to be the minimum bactericidal concentration (MBC) against ESBL producing K. pneumoniae isolates.