AMB Volume 42, Issue 2, 2026 Pages 317-328 https://doi.org/10.59393/amb26420214
Chromium, Cadmium, and Copper-Resistance and Removal Potential of Bacteria and Fungi Isolated from Two Bryophytes’ Surfaces and Substratum
Jewo A.O., Ejechi B.O., Akpomie O.O.
Bryophytes are known to accumulate heavy metals on their surfaces by biosorption; hence, it is probable that microorganisms inhabiting their surfaces may be metal-tolerant. Bacteria and fungi were therefore isolated from the surface and substratum of two mosses, Polytrichum commune and Tortula muralis, used as test bryophytes, using nutrient agar (NA) and malt extract agar (MEA). The isolates were initially identified by standard morphological and biochemical methods and subsequently screened for metal-resistance in NA and MEA containing 100 mg/L Cr and Cd, and Cu 600 mg/L. Metal-tolerance index (MTI) was determined in nutrient broth containing 300 mg/L Cr and Cd, and MEA containing 800mg/L for Cu. Isolates with MTI >0.50 for the three metals were selected, identified by molecular methods, and tested for minimum inhibitory concentration (MIC) and removal of Cr, Cd, and Cu from aqueous media. The selected isolates were tested for MTI using combined concentrations of Cr, Cd, and Cu. The isolates’ identities were confirmed as Pseudomonas aeruginosa, Bacillus cereus, Proteus mirabilis, and Aspergillus oryzae, and their MICs (mg/L) were: Cr, 350-550; Cd, 300-350; and Cu, 650-750. Metal removal from the aqueous media by the four organisms was 14.06-77.28% with significant differences by metal (F=4.40-631.40; P=0.037- 0.000) and by organism (F=122.90-541.80; P=0.000). The MTI of the combined metals was low (<0.50), and it declined with increasing concentrations. Pseudomonas aeruginosa tolerated the highest combined concentrations, albeit with 0.10 MTI. Thus, the MIC levels and metal-removal capabilities indicate these organisms as potentially useful for bioremediation of metal-polluted sites.
Keywords: Polytrichum commune; Tortula muralis, microbial metal-tolerance; chromium; cadmium; copper
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