Pyrene Degradation Accelerated by Constructed Consortium of Bacterium and Microalga: Effects of Degradation Products on the Microalgal Growth

Abstract

Abundant microbes including bacteria, fungi, or algae are capable of biodegrading polycyclic hydrocarbons (PAHs). However, pure cultures never occur in the contaminated environments. This study aimed to understand the general potential mechanisms of interactions between microbes under pollution stress by constructing a consortium of PAH-degrading microalga (Selenastrum capricornutum) and bacterium (Mycobacterium sp. strain A1-PYR). Bacteria alone could grow on the pyrene, whereas the growth of algae alone was substantially inhibited by the pyrene of 10 mg L(-1). In the mixing culture of algae and bacteria, the growth rate of algae was significantly increased from day 4 onward. Rapid bacterial degradation of pyrene might mitigate the toxicity of pyrene to algae. Phenolic acids, the bacterial degradation products of pyrene, could serve as the phytohormone for promoting algal growth in the coculture of algae and bacteria. In turn, bacterial growth was also enhanced by the algae presented in the mixing culture. Consequently, the fastest degradation of pyrene among all biodegradation systems was achieved by the consortium of algae and bacteria probably due to such interactions between the two species by virtue of degradation products. This study reveals that the consortium containing multiple microbial species is high potential for microbial remediation of pyrene-contaminated environments, and provides a new strategy to degrade the recalcitrant PAHs.

Current State of Knowledge in Microbial Degradation of Polycyclic Aromatic Hydrocarbons (PAHs): A Review

“…An algal–bacterial consortium consisting of Chlorella sorokiniana and Pseudomonas migulae was also reported for the degradation of phenanthrene under photosynthetic conditions and without an external source of oxygen (Munoz et al, 2003). In another study, accelerated pyrene degradation by a bacterial-algal consortium was reported under photosynthetic condition (Luo L. et al, 2014; Luo S. et al, 2014). These studies indicate that microalgae can be used singly or along with bacteria as a potential candidate for biodegradation of PAHs.…”

“…Removal and transformation of seven high molecular weight PAHs in water was reported by live and dead cells of a freshwater microalga, Selenastrum capricornutum under gold and white light irradiation. The removal efficiency of PAHs, and the effectiveness of live and dead cells, was found to be predominantly PAH dependent (Ke et al, 2010; Luo L. et al, 2014; Luo S. et al, 2014). The first study on the potential of algal–bacterial microcosms was reported for the biodegradation of aromatic pollutants comprising salicylate, phenol and phenanthrene in a one-stage treatment (Borde et al, 2003).…”

The effect of the algal microbiome on industrial production of microalgae

“…established a consortium consisting of microalgae ( Selenastrum capricornutum ) and a bacterium ( Mycobacterium sp. strain A1‐PYR) that achieved faster degradation of pyrene than the systems that used algae or bacteria alone (Luo et al ., ). The same result was obtained by a synthetic consortium combining Synechocystis sp.…”

“…Algal cells not only provide stable habitats for the bacteria but also concentrate pollutants to enhance bioavailability for bacterial degradation (Gutierrez et al, 2014). Algal-bacterial consortia successfully achieved higher biodegradation or removal rates of pollutants than single species (Luo et al, 2014).…”

“…Apart from playing a role in enhancing microalgae production, associated bacteria can help the algae to perform more complex tasks with diverse applications. For instance, algae and bacteria cooperate in faster and more efficient removal of organic and inorganic waste and hazardous substances in wastewater treatment (Su et al, 2012;Luo et al, 2014;Cavaliere et al, 2017). In turn, bacterial and viral pathogens are able to weaken or decompose the algal cell wall, which is a crucial step in algal-based extraction of chemicals and could also be explored to tackle frequently occurring harmful algae blooms at an early stage of the bloom (Wilson et al, 2002;Chen et al, 2014).…”