Responses of Rhizosphere Fungal Communities to the Sewage Sludge Application into the Soil

Abstract

Due to the increasing sewage sludge production in the world and problems with its disposal, an application of sludge to the soil appears to be a suitable solution considering its fertilizer properties and ability to improve the soil physical conditions. On the other hand, the sludge may also contain undesirable and toxic substances. Since soil microorganisms are sensitive to environmental changes, they can be used as indicators of soil quality. In this study, we used sewage sludge (SS) from two municipal wastewater treatment plants (SS-A and SS-B) in the dose of 5 t/ha and 15 t/ha in order to determine possible changes in the fungal community diversity, especially arbuscular mycorrhizal fungi (AMF), in the rhizosphere of Arundo donax L. Rhizosphere samples were collected in summer and autumn for two consecutive years and the fungal diversity was examined using terminal restriction fragment length polymorphism and 18S rDNA sequencing. Fungal alpha diversity was more affected by SS-A than SS-B probably due to the higher heavy metal content. However, based on principal component analysis and ANOSIM, significant changes in overall fungal diversity were not observed. Simultaneously, 18S rDNA sequencing showed that more various fungal taxa were detected in the sample with sewage sludge than in the control. Glomus sp. as a representative of AMF was the most represented. Moreover, Funneliformis in both samples and Rhizophagus in control with Septoglomus in the sludge sample were other representatives of AMF. Our results indicate that the short-term sewage sludge application into the soil does not cause a shift in the fungal community composition.

Sewage Sludge as a Soil Amendment for Growing Biomass Plant Arundo donax L.

“…In these experiments, we found that the total microbial biomass statistically increased with the addition of SS [22]. Likewise, the alpha diversity of fungal rhizosphere communities was significantly increased in sludge-added soils, and more varied fungal taxa were detected in the soil sample with SS when compared to the control treatment [23]. Enhanced biological parameters of the soil were also confirmed by Kołodziej et al [19] by measuring the soil enzymes as markers of biological fertility during the cultivation of sweet sorghum in an SS-amended soil.…”

“…In our previous papers, samples of municipal SS were evaluated for the responses of rhizosphere bacterial [22] and fungal [23] communities to the application of SS into the soil. The present work aimed to assess the effect of SS on the growth parameters and the biomass yield of giant reed plants.…”

The impact of sewage sludge on the fungal communities in the rhizosphere and roots of barley and on barley yield

“…Using biological approaches to determine the ecological effects of land application of municipal SS has been preferred widely for decades [ 4 , 28 ]. Alpha diversity [ 34 ] indicates the diversity that exists within a sample/location, and it is measured by the number of species or the richness of species but other diversity indices are often used, such as Shannon and Simpson [ 35 ].…”

“…The quantity and purity of DNA were measured spectrophotometrically with a NanoDrop-1000 Spectrophotometer (Thermo Fisher Scientific Inc., Waltham, MA, USA), and samples were diluted to the same final concentration (20 ng μL −1 ) and stored at −20°C. Molecular analysis of partial 18S rRNA gene using two conserved primer pairs NS1 with NS4 [ 26 ] and NS31 with AM1 [ 27 ] in terminal restriction fragment length polymorphism (T-RFLP) was performed according to our previous study [ 28 ]. The second primer pair is specific for AMF; however, it should be noted that it also amplifies DNA from Ascomycota and Basidiomycota to a limited extent [ 28 , 29 , 30 ].…”

“…Statistically significant differences among samples were tested using analysis of variance (ANOVA) and subsequently using post hoc pairwise comparisons based on Fisher’s least significant difference (LSD) procedure at the 95% confidence level, using the software Statgraphics x64 (Statpoint Technologies, Inc., Warrenton, VA, USA). Diversity indices such as the Simpson index, Shannon’s diversity index, and Pielou evenness index for the evaluation of alpha diversity also were calculated according to our previous study [ 28 ]. Species richness, Simpson, and Shannon indices were also used for SHE analysis [ 31 ].…”