ENVIRONMENTAL BIOTECHNOLOGY Heavy metals species affect fungal-bacterial synergism during the bioremediation of fluoranthene Xiao-kui Ma 1 & Ning Ding 1 & Eric Charles Peterson 2 & Andrew J. Daugulis 3 Received: 29 February 2016 /Revised: 25 April 2016 /Accepted: 28 April 2016 /Published online: 13 May 2016 # Springer-Verlag Berlin Heidelberg 2016 Abstract The co-occurrence of polycyclic aromatic hydro- carbons (PAHs) with heavy metals (HMs) is very common in contaminated soils, but the influence of HMs on fungal- bacterial synergism during PAH bioremediation has not been investigated. The bioremediation of fluoranthene- contaminated sand using co-cultures of Acremonium sp. P0997 and Bacillus subtilis showed increases of 109.4 and 9.8 % in degradation compared to pure bacterial and fungal cultures, respectively, removing 64.1 ± 1.4 % fluoanthene in total. The presence of Cu 2+ reduced fluoranthene removal to 53.7 ± 1.7 %, while inhibiting bacterial growth, and reducing translocation of bacteria on fungal hyphae by 49.5 %, in terms of the bacterial translocation ratio. Cu 2+ reduced bacterial dif- fusion by 46.8 and 31.9 %, as reflected by D (a bulk random motility diffusional coefficient) and D eff (the effective one- dimensional diffusion coefficient) compared to the control without HM supplementation, respectively. However, Mn 2+ resulted in a 78.2 ± 1.9 % fluoranthene degradation, representing an increase of 21.9 %, while enhancing bacterial growth and bacterial translocation on fungal hyphae, showing a 12.0 % increase in translocation ratio, with no observable impact on D and D eff . Hence, the presence of HMs has been shown to affect fungal-bacterial synergism in PAH degrada- tion, and this effect differs with HM species. Keywords Fungal-bacterial synergism . Heavy metals species . Bioremediation . Bacterial movement . Fungal highway Introduction Bioremediation is an efficient tool to transform pollutants such as polycyclic aromatic hydrocarbons (PAHs) to less hazardous/non-hazardous forms in an eco-friendly man- ner, with less input in terms of chemicals, energy, and time (Haritash and Kaushik 2009). Many attempts to im- prove degradation of PAHs or other hydrophobic organic pollutants (HOCs) often focus on bioremediation with fungal–bacterial consortia exhibiting synergistic effects in heterogeneous soil environments (Furuno et al. 2010; Husaini et al. 2008). The synergistic degradation from fungal-bacterial interactions has been partly ascribed to the increased dispersal of degradative bacteria along the hyphae of the fungal partner (Boersma et al. 2010; Furuno et al. 2010; Kohlmeier et al. 2005), as mycelial networks can act as Bhighways, ^ allowing bacteria to overcome motility restrictions in soil and reach remote areas, possi- bly due to the presence of water films on fungal hyphae, which permits bacterial transport along fungal hyphae (Knudsen et al. 2013; Kohlmeier et al. 2005). Thus, the concept of a Bfungal highway^ can provide new insight into mechanisms for synergistic biodegradation from fungal-bacterial interaction and could have significant benefits for developing novel bioremediation strategies for PAHs pollution in soils (Banitz et al. 2013). * Xiao-kui Ma biomarkuis@gmail.com 1 Key Laboratory of Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Developing of Endangered Crude Drugs in Northwest of China, College of Life Science, Shaanxi Normal University, Xi’an 710055, Shaanxi, People’ s Republic of China 2 Industrial Microbiology, Universidad Icesi, Cl. 18 #122-135, Cali, Valle del Cauca, Colombia 3 Department of Chemical Engineering, Queen’ s University, K7L 3N6, Kingston, ON, Canada Appl Microbiol Biotechnol (2016) 100:7741–7750 DOI 10.1007/s00253-016-7595-4