Ignored fungal community in activated sludge wastewater treatment plants: diversity and altitudinal characteristics

Abstract

Fungi are important contributors to the various functions of activated sludge wastewater treatment plants (WWTPs); however, the diversity and geographic characteristics of fungal populations have remained vastly unexplored. Here, quantitative polymerase chain reaction and 454 pyrosequencing were combined to investigate the abundance and diversity of the activated sludge fungal communities from 18 full-scale municipal WWTPs in China. Phylogenetic taxonomy revealed that the members of the fungal communities were assigned to 7 phyla and 195 genera. Ascomycota and Basidiomycota were the most abundant phyla, dominated by Pluteus, Wickerhamiella, and Penicillium. Twenty-three fungal genera, accounting for 50.1 % of the total reads, were shared by 18 WWTPs and constituted a core fungal community. The fungal communities presented similar community diversity but different community structures across the WWTPs. Significant distance decay relationships were observed for the dissimilarity in fungal community structure and altitudinal distance between WWTPs. Additionally, the community evenness increased from 0.25 to 0.7 as the altitude increased. Dissolved oxygen and the C/N ratio were determined to be the most dominant contributors to the variation in fungal community structure via redundancy analysis. The observed data demonstrated the diverse occurrence of fungal species and gave a marked view of fungal community characteristics based on the previously unexplored fungal communities in activated sludge WWTPs.

Industrial Effluents Harbor a Unique Diversity of Fungal Community Structures as Revealed by High-throughput Sequencing Analysis

“…The phylum-level phylogenetic fingerprint of fungal communities in this study produced a total of 6 phyla dominated by Ascomycota whose relative abundance ranged from 23.29% in Dixon to 38.31% in Ford samples, followed by Basidiomycota with a relative abundance of 17.34% in Capegate to 33.51% in Chemreem effluents. Similar to the present findings, previous studies on fungal diversity in industrial wastewater treatment plants using clone libraries found fungal communities to be dominated by fungi of the phyla Ascomycota and Basidiomycota [16,20,31]. The overwhelming abundance of fungi belonging to these two phyla may be attributed to the fact that Ascomycota constitutes the largest phylum of fungi encompassing more than 33,000 named species Fig.…”

“…Members of Basidiomycota and Glomeromycota were positively correlated with NO 3 and PO 4 concentrations. Trichosporon (Basidiomycota) have been reported to be able to denitrify and could cooperate with bacteria in nitrogen removal [20], while Archaeosporales (Glomeromycota) enhance phosphorous and nitrogen supply to host [48]. Fungi of the phylum Ascomycota were observed to be negatively influenced by pH, which agrees with the findings of Maza-Marquez et al [16], who reported similar findings in wastewater treatment systems.…”

“…were the most frequently cultured fungi recovered from anoxic-activated sludge samples [36] and industrial wastewater [37]. Members of the genus Candida have the ability to adsorb and/or accumulate metals from their surroundings, also in addition to their ability to produce extracellular polymeric substances for biofilm formation, flocculation, and adhesion processes [20]. Perhaps their most important contribution as it relates to wastewater treatment is that they limit bacterial contamination and so improve the secondary industrial wastewater treatment process [38].…”

“…Aspergillus have a high capacity to reduce the phenolic compounds with significant reduction of COD in industrial wastewater [43]. Fungi of the genus Penicillium are known to improve the bioconversion of organic compounds and enhance the dewaterability and filtration during wastewater treatment [20]. Previously, Trichosporon spp.…”

“…They are involved in several pathways in wastewater treatment systems, including organic biodegradation [17], decolourization [18], and detoxification processes [19]. When compared to bacteria, fungi are more likely to be efficiently involved in bioremediation processes [20]. Their production of extracellular enzymes is of particular significance in their ability to degrade higher molecular weight pollutants such as polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs), and polybrominated diphenyl ethers (PBDEs) [21].…”