Existence of a novel heavy metal-tolerant Pseudomonas aeruginosa strain Zambia SZK-17 Kabwe 1: the potential bioremediation agent in the heavy metal-contaminated area.

Bacterial biomass may serve as an important environmental cleaning agent to toxic heavy metal ions at the expense of chemical processes which are not environmentally friendly. This study aimed at characterizing bacterial agents which could serve as a potential in situ bioremediation agent at the site of isolation. The characterization was performed using both phenotypic and molecular approaches. A novel Pseudomonas aeruginosa strain Pseudomonas aeruginosa Zambia SZK17 Kabwe1 was successfully isolated, identified, and characterized. The strain showed a promising tolerance to heavy metals such as copper (2 mM), zinc, nickel (2 mM), cobalt (1 mM), and cadmium (0.5 mM) at the laboratory level. The bacterium has shown the bioaccumulation of at least 60% of copper (II) sulfate (0.3655 mg/l) with R = 69.75%, cadmium (II) chloride (0.0241 mg/l) with R = 69.98%, zinc (II) chloride (0.1389 mg/l) with R = 69.91%, nickel (II) chloride (0.1155 mg/l) with R = 69.92%, and cobalt (II) chloride (0.593 mg/l) with R = 69.92%. The highest bioaccumulation has been observed in heavy metals cadmium, zinc, nickel, and cobalt. Characterization of the bacterium on pH has revealed that at a very high pH (≥ 9) and lower (≤ 5.5) pH, the bacterium tended to have reduced growth with optimum growth at pH 8. The high temperature at around 40 °C had a negative effect on the growth performance of the bacterium while optimum growth was observed at 28 °C. This novel P. aeruginosa strain has shown the phenotypic attributes to become a potential bioremediation agent; however, further investigation needs to be done to understand the genes and or molecular mechanisms that drive their tolerance to multiple heavy metals.

miRNAs that associate with conjunctival inflammation and ocular Chlamydia trachomatis infection do not predict progressive disease.

We previously showed that conjunctival miR-147b and miR-1285 were upregulated in Gambian adults with inflammatory scarring trachoma, and miR-155 and miR-184 expression was strongly associated with conjunctival inflammation and ocular Chlamydia trachomatis infection in children from Guinea-Bissau. We investigated whether the single or combined expression of miR-147b, miR-1285, miR-155 and miR-184 was able to identify individuals with increased risk of incident or progressive scarring trachoma. Conjunctival swab samples were collected from 506 children between the ages of 4 and 12 living in northern Tanzania. These 506 samples formed the baseline sample set of a 4-year longitudinal study. Chlamydia trachomatis infection was diagnosed by droplet digital PCR and expression of miR-155, miR-184, miR-1285 and miR-147b was tested by qPCR. Individuals were assessed for incidence and progression of conjunctival scarring by comparison of conjunctival photographs taken at baseline and 4 years later. miR-184 and miR-155 were strongly associated with inflammation and infection at baseline; however, no miR was associated with 4-year scarring incidence or progression. miR-184 expression was more strongly downregulated during inflammation in non-progressors relative to progressors, suggesting that a disequilibrium in the efficiency of wound healing is a significant determinant of progressive conjunctival fibrosis.