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Stamou GP, Konstadinou S, Monokrousos N, Mastrogianni A, Orfanoudakis M, Hassiotis C, Menkissoglu-Spiroudi U, Vokou D, Papatheodorou EM. The effects of arbuscular mycorrhizal fungi and essential oil on soil microbial community and N-related enzymes during the fungal early colonization phase. AIMS Microbiol 2017; 3:938-959. [PMID: 31294199 PMCID: PMC6604959 DOI: 10.3934/microbiol.2017.4.938] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2017] [Accepted: 11/23/2017] [Indexed: 11/18/2022] Open
Abstract
The arbuscular mycorrhizal fungi (AMF) and the essential oils are both agents of sustainable agriculture, and their independent effects on the community of free-living soil microbes have been explored. In a tomato pot experiment, conducted in a sandy loam mixture, we examined the independent and joint effects of inoculation with the fungus Rhizophagous irregularis and the addition of Mentha spicata essential oil on the structure of the soil microbial community and the activity of soil enzymes involved in the N-cycle, during the pre-symbiosis phase. Plants were grown for 60 days and were inoculated with R. irregularis. Then pots were treated with essential oil (OIL) weekly for a period of a month. Two experimental series were run. The first targeted to examine the effect of inoculation on the microbial community structure by the phospholipid fatty acids analysis (PLFAs), and enzyme activity, and the second to examine the effects of inoculation and essential oil addition on the same variables, under the hypothesis that the joint effect of the two agents would be synergistic, resulting in higher microbial biomass compared to values recorded in singly treated pots. In the AMF pots, N-degrading enzyme activity was dominated by the activity of urease while in the non-inoculated ones by the activities of arylamidase and glutaminase. Higher microbial biomass was found in singly-treated pots (137 and 174% higher in AMF and OIL pots, respectively) compared with pots subjected to both treatments. In these latter pots, higher activity of asparaginase (202 and 162% higher compared to AMF and OIL pots, respectively) and glutaminase (288 and 233% higher compared to AMF and OIL pots, respectively) was found compared to singly-treated ones. Soil microbial biomasses and enzyme activity were negatively associated across all treatments. Moreover, different community composition was detected in pots only inoculated and pots treated only with oil. We concluded that the two treatments produced diverging than synergistic effects on the microbial community composition whereas their joint effect on the activity of asparaginase and glutaminase were synergistic.
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Affiliation(s)
- George P Stamou
- School of Economics, Business Administration and Legal Studies, International Hellenic University, 57001 Thessaloniki, Greece
| | | | - Nikolaos Monokrousos
- Department of Ecology, School of Biology, AUTH, 54124 Thessaloniki, Greece.,Department of Soil Science of Athens, Institute of Soil and Water Resources, Hellenic Agricultural Organization-Demeter, 14123 Lykovrisi, Greece
| | - Anna Mastrogianni
- Department of Ecology, School of Biology, AUTH, 54124 Thessaloniki, Greece
| | - Michalis Orfanoudakis
- Department of Forestry and Management of the Environment and Natural Resources, Democritus University of Thrace, 68200 Orestiada, Greece
| | - Christos Hassiotis
- Department of Natural Environment and Forestry, Technical University of Larissa, 43100 Karditsa, Greece
| | | | - Despoina Vokou
- Department of Ecology, School of Biology, AUTH, 54124 Thessaloniki, Greece
| | - Efimia M Papatheodorou
- School of Economics, Business Administration and Legal Studies, International Hellenic University, 57001 Thessaloniki, Greece.,Department of Ecology, School of Biology, AUTH, 54124 Thessaloniki, Greece
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