Advances in Heavy Metal Bioremediation: An Overview

The pollution of toxic heavy metals is considered one of the most important environmental issues which has accelerated dramatically due to changing industrial activities. This review focuses on the most common methods, strategies, and biological approaches of heavy metal bioremediation. Also, it provides a general overview of the role of microorganisms in the bioremediation of heavy metals in polluted environments. Advanced methods of heavy metal remediation include physicochemical and biological methods; the latter can be further classified into in situ and ex situ bioremediation. The in situ process includes bioventing, biosparging, biostimulation, bioaugmentation, and phytoremediation. Ex situ bioremediation includes land farming, composting, biopiles, and bioreactors. Bioremediation uses naturally occurring microorganisms such as Pseudomonas, Sphingomonas, Rhodococcus, Alcaligenes, and Mycobacterium. Generally, bioremediation is of very less effort, less labor intensive, cheap, ecofriendly, sustainable, and relatively easy to implement. Most of the disadvantages of bioremediation relate to the slowness and time-consumption; furthermore, the products of biodegradation sometimes become more toxic than the original compound. The performance evaluation of bioremediation might be difficult as it has no acceptable endpoint. There is a need for further studies to develop bioremediation technologies in order to find more biological solutions for bioremediation of heavy metal contamination from different environmental systems.

Indigenous multiresistant bacteria of Cupriavidus pauculus IrC4 isolated from Indonesia as a heavy metal bioremediation agent

Irawati W, Winoto SE, Kusumawati L, Pinontoan R. 2021. Indigenous multiresistant bacteria of Cupriavidus pauculus IrC4 isolated from Indonesia as a heavy metal bioremediation agent. Biodiversitas 22: 3349-3355. Heavy metal pollution is a serious environmental problem because it endangers humans, animals, and plants. Bioremediation of heavy metals using bacteria is an effective method to remove heavy metals. Cupriavidus pauculus IrC4 is an indigenous multi-resistant bacteria isolated from Indonesia. This study aims to determine the growth of this strain in a medium containing cadmium, mercury, lead, copper, and its ability to accumulate heavy metal. Bacterial resistance was observed by cultivating bacteria on a Luria Bertani medium containing various concentrations of heavy metals. Heavy metal accumulation was measured using atomic absorption spectrophotometer. The study showed that this strain could grow in a solid medium containing 5 mM cadmium, 13 mM lead, and 4 mM mercury, also in 0.5 mM of the heavy metal mixture. A high concentration of heavy metals resulted in lag phase elongation and logarithmic growth phase inhibition. C. pauculus IrC4 could accumulate copper, lead, and cadmium and lead up to 371.42 mg, 254.4 mg, 5.8 mg heavy metals per gram of dry weight of cells, respectively. In conclusion, this strain is a promising bacterium for use as a heavy metal bioremediation agent.