Microalgae–bacteria biofilms: a sustainable synergistic approach in remediation of acid mine drainage

Abstract

Microalgae and bacteria offer a huge potential in delving interest to study and explore various mechanisms under extreme environments. Acid mine drainage (AMD) is one such environment which is extremely acidic containing copious amounts of heavy metals and poses a major threat to the ecosystem. Despite its extreme conditions, AMD is the habitat for several microbes and their activities. The use of various chemicals in prevention of AMD formation and conventional treatment in a larger scale is not feasible under different geological conditions. It implies that microbe-mediated approach is a viable and sustainable alternative technology for AMD remediation. Microalgae in biofilms play a pivotal role in such bioremediation as they maintain mutualism with heterotrophic bacteria. Synergistic approach of using microalgae-bacteria biofilms provides supportive metabolites from algal biomass for growth of bacteria and mediates remediation of AMD. However, by virtue of their physiology and capabilities of metal removal, non-acidophilic microalgae can be acclimated for use in AMD remediation. A combination of selective acidophilic and non-acidophilic microalgae together with bacteria, all in the form of biofilms, may be very effective for bioremediation of metal-contaminated waters. The present review critically examines the nature of mutualistic interactions established between microalgae and bacteria in biofilms and their role in removal of metals from AMDs, and consequent biomass production for the yield of biofuel. Integration of microalgal-bacterial consortia in fuel cells would be an attractive emerging approach of microbial biotechnology for AMD remediation.

Extremophile Microalgae: the potential for biotechnological application

“…In particular, the possible synergistic role of acidophilic and non‐acidophilic microalgae together with bacteria, all contained in biofilms, has been reported for AMD bioremediation (Abinandan et al. , Marques ). In this context, Hammed et al.…”

Toward the Enhancement of Microalgal Metabolite Production through Microalgae–Bacteria Consortia

“…The most common co-cultivation system is with both species on suspension [30][31][32]. Other ways of co-culture are by the immobilization of one of the microorganisms in biofilms while the other remains in suspension [33,34], with biofilms or different carriers embedding both microorganisms [35][36][37][38], or by the separation of the two species with a membrane [38,39]. Additionally, the growth-promoting effects of bacteria can also be evaluated on axenic microalgal cultures by cultivation with bacterial extracts [40,41] or through the addition of bacterial volatiles and gas exchange [42].…”

Characterization and Treatment of Mine Drainage

“…The NaOH-CA adsorbed significantly more metals than raw coal ash and pytoremediation following adsorption by NaOH-CA removed 89.2-99.9% of the metals. A critical review was made to examines the nature of mutualistic interactions established between microalgae and bacteria in biofilms and their role in removal of metals from AMD (Abinandan et al, 2018). In addition, the integration of microalgal-bacterial consortia in fuel cells would be an attractive emerging approach of microbial biotechnology for AMD remediation.…”