Functional Diversity of Soil Microbial Communities in Environments Shaped by Anthropogenic Activities

Dear Colleagues,

The current geological epoch, i.e., the Anthropocene, is profoundly affected by the expansion of environments shaped by human activities such as agriculture, industry, urbanization, etc. As a consequence, the human population is facing, on the one hand, the consequences of more than half of the terrestrial ecosystems having turned into anthropogenic ecosystems, and on the other hand, the dependence on services provided by ecosystems of unknown functional mechanisms. Soil microbial communities are undoubtedly key players in vital ecosystem processes such as primary production, decomposition, nutrient cycling, and carbon storage. For a long time, taxonomic richness has been used as an indirect measure of the potential contribution of microbial communities in the functioning of ecosystems. In recent decades, this perspective has been challenged, and the diversity of functions performed by microbial communities has received increasing recognition as the missing link between biodiversity patterns and ecosystem functions.

In this Special Issue of Agronomy, we invite you to submit both original research and review-type contributions regarding the use of available tools (metatranscriptomic approach, enzymatic assay, etc.) for the assessment of changes in the functional diversity of soils under the pressure of any anthropogenic activity.

Dr. Franco Magurno
Dr. Zoltán Kende
Guest Editors

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• soil microbial communities
• functional diversity
• anthropogenic activities
• biodiversity
• ecosystem functions
• ecosystem processes

Title: The way of disposing the hard coal by-products influences physicochemical properties of the soil and the vegetation succession in the post coal mine ecosystems
Authors: Jawdat Bakr; Agnieszka Kompała-Bąba; Wojciech Bierza; Damian Chmura; Agnieszka Hutniczak; Jacek Kasztowski; Bartosz Jendrzejek; Adrian Zarychta; Gabriela Woźniak
Affiliation: Institute of Biology, Biotechnology and Environmental Protection, Faculty of Natural Sciences, University of Silesia in Katowice; 28 Jagiellońska Str., 40-032 Katowice, Poland
Abstract: The way of disposing of rock mineral material has a significant impact on subsequent spontaneous vegetation succession, soil parameters, and soil respiration. We compared 7 spontaneous vegetated samples from a large (2 km²) borrow pit (Bp) used to dispose of the by-products of a hard coal mine with 7 plots from 4 coal mine spoil heap-piles (Hp) using detrended correspondence analysis (DCA).We used BIOLOG EcoPlates for community-level physiological profiles (CLPP) to assess the microbial catabolic activity of the substrate. The substrate in the Bp was characterized by higher water content (SWC-14.83%) and lower temperature (St-19.8°C) compared to Hp substrate (SWC-9.19% and St-21.5°C, respectively). The Bp had a more diverse plant community structure, indicated by a higher number of species (S-41), a higher evenness index (E-0.73), and a higher diversity index (H’-2.71), with fewer dominant species (D-0.14) than the heap-piles plant communities (S-26, E-0.56, H’-1.81, and D-0.36). Higher Rao’s quadratic entropy, functional richness, and functional divergence were also calculated from plant functional traits in Bp samples. Although Bp samples showed higher total microbial biomass, bacteria/fungi ratio, and gram+/gram- ratio, and Hp samples showed higher soil enzymatic activity, microbial functional diversity, and catabolic activity, these differences were not remarkable. Soil respiration was two-folds higher (0.49 g-CO2/h/m²) from the Bp substrate, attributed to higher species richness and diversity, higher water content, higher water holding capacity, and lower and more stable soil temperature. The borrow-pit method of disposing of rock mineral material can be suggested to speed up spontaneous vegetation succession, increase plant diversity, and create conditions favorable for establishing new plant communities. This research provides new insights into the effects of burying hard coal by-products in borrow pits and offers guidance for the management of hard coal mining.

Title: Bacillus strains isolated from agroforestry systems in the ama-zon promote the açaí palm seedlings growth when inoculated as a consortium
Authors: Josinete Torres Garcias; Rosiane do Socorro dos Reis de Sousa; Suania Maria do Nascimento Sousa; Lucimar Di Paula dos Santos Madeira; Allana Laís Alves Lima; Jackeline Rosseti Mateus; Joyce Kelly R. da Silva; Lucy Seldin; Hervé Louis Ghislain Rogez; Joana Montezano Marques
Affiliation: Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém, Pará, Brasil
Abstract: The present work tested the hypothesis that açaí palm planted in agroforestry systems can recruit plant growth-promoting rhizobacteria (PGPR) to its rhizosphere. For this purpose, rhizospheric soil samples were collected in an Agroforest System (AFS) area for PGPR screening. CFU counts of the soil samples were 3.5 x 106 CFU/g, with no statistically significant differences between plants (p<0.05). Regarding PGPR characteristics, of 44 isolated strains, 18% produced siderophores, 9% mineralized organic phosphate, 15% solubilized inorganic phosphate, 7% produced IAA and an-timicrobial substances. Strains AP4-03, AP1-33 and AP2-36, were affiliated with the genus Bacillus sp. and produced of indole-3-acetic acid (IAA) at 1.45, 1.35 and 2.02 µg/mL, respectively. Fur-thermore, these strains were able to inhibit the growth of the fungus Pestalotiopsis by 69%, 67% and 71%, respectively. Regarding the antifungal activity of bacterial extracts, inhibition zones of 23mm (AP-03), 20mm (AP-33) and 18mm (AP-36), with 96% and 92% inhibition at 50 mg/mL (AP4 -03 and AP1-33) and 100% inhibition at 45 mg/mL (AP2-36) were observed. Considering seedling ger-mination, açaí palms inoculated with strain AP1-33 statistically differed from the controls in terms of root length and hypocotyl length. Furthermore, treatments inoculated with strain AP2-36 or all strains in consortium differed when only the hypocotyl length was compared to the control. PGPR strains were able to improve the initial development of açaí plants.