The bacterial metabolism of propane and the pathway(s) involved are poorly understood, as the relative importance of terminal versus subterminal oxidation of propane, via propan‐1‐ol and propan‐2‐ol, respectively, is still unclear. In the case of bacteria, the ability to oxidize propane appears to be confined mainly to the Gram‐positive Corynebacterium‐Nocardia‐Mycobaterium‐Rhodococcus complex. Studies on propane oxidation have been hampered by a lack of firm enzymological data; for example, to date there are no reports of a purified propane oxygenase system. However, oxygenase activity has been confirmed by the production of propan‐1‐ol and/or propan‐2‐ol, and more recentlly by the co‐oxidation of propene to 1,2‐epoxypropane in cell extracts of propane‐grown cells. Here, we review the use of genetic, biochemical and immunological techniques to assess the role(s) of terminal and subterminal oxidation in the metabolism of propane by Rhodococcus rhodochrous PNKb1 and present a general overview of the topic.

The threat of heavy metals pollution to public health and wildlife has led to an increased interest in developing systems that can remove or neutralize its toxic effects in industrial effluents and municipal wastewater. Tolerance to a range of heavy metal ions was determined for bacteria which had been isolated from wastewater collected from Makkah city, Saudi Arabia. Isolates were tolerant to cupper, cadmium, zinc, and cobalt although the levels of tolerance to the different concentrations of metal ions were specific for each isolate. One isolate was able to tolerate all four metal ions tested; phenotypic and genotypic investigation revealed that isolate (S7) resembled similarities with Pseudomonas aeruginosa. The results of this study showed the potential applicability of the isolated heavy metal-tolerant strain Pseudomonas aeruginosa (S7) in the treatment of heavy metal containing solutions. Further studies on the genomic structure of isolate (S7) are required to investigate its capabilities to remove/reduce heavy metals in contaminated microcosms. Methods Isolation of bacteria Water samples were taken from industrial wastewater ponds found in Makkah City, Saudi Arabia. The samples were collected in sterile screw-capped bottles containing 0.1% sodium thiosulfate to prevent bacterial oxidation. The collected samples were preserved in an ice box and transported to laboratory for direct bacteriological examination. Plate dilution method was employed for bacterial isolation [9] using LB agar supplemented with 0.5 mM of Cu(NO 3) 2 , CdCl 2 , Zn(NO 3) 2 and Co(NO 3) 2 respectively. An aliquot of 50 µl of each dilution was spread on the surface of LB agar plates; three replicates of each dilution were prepared. Inoculated plates were incubated at 30-35ºC for 24-48 h. The O.D. readings of each culture were taken at 0, 24, 48 and 72 h. The results were recorded based on three trials for each experiment. Identification tests Random collection of different colonies with various morphological characteristics was selected from LB agar plates. All unknown colonies were subjected to microscopic, biochemical and molecular identification as follows: Microscopic examination: Gram staining technique was carried out as described by Reddy et al. [9]. Biochemical characterization: Biochemical testes included: Oxidase, Catalase tests, Fermentation of Sugars, Urease test, IMVIC Test, aesculine hydrolysis, gelatin hydrolysis were carried out according to Reddy et al. [9]. J o u rn al of M ic ro b ia l & Bioc h e m ic a l Te chno lo g y