30 May 2017, a new book chapter ‘Arbuscular Mycorrhizal Fungi in Hypoxic Environments’

A new book chapter titled ‘Arbuscular Mycorrhizal Fungi in Hypoxic Environments’,

in Varma et al. (Eds): Mycorrhiza – Function, Diversity, State of Art, Springer Verlag.



Hypoxia (low O2 concentration) or even anoxia (devoid of O2) in plant rhizosphere are common phenomena that can be consequence of flooding, submergence, soil compaction, or are a specific characteristic of some extreme ecosystems (e.g. due to geological CO2 release in natural CO2 springs or mofettes). The frequency and severity of flooding events will dramatically increase in the future, as projected by climate change models. Therefore, understanding the response of different organisms to soil hypoxia, including crop plants, and their interaction with symbiotic and ubiquitous arbuscular mycorrhizal (AM) fungi is becoming increasingly important in order to enhance plant yield and to promote sustainable agriculture in the future. Plants and soil fungi are known to be obligate aerobes and are sensitive to O2 deficiency since they need a sufficient amount of this gas to support their aerobic metabolism. However, some specific morphological and metabolic adaptations also enable plants to survive in habitats where O2 availability is severely limited. Moreover, recent reports show that diverse plant root endophytic fungal communities exist in these ecosystems with some specific (new) taxa being reported to even thrive there. This includes obligate biotrophic AM fungi that fully depend on the plant-derived carbon source. A new aspect in the biology of these organisms originating from the research into hypoxic environments is that in addition to carbon, they can also use a plant-derived O2 source delivered into the submerged organs via plant’s root aeration systems (e.g. aerenchyma). Moreover, in the field of community ecology, extreme hypoxic environments (e.g. mofettes) have been shown to represent a powerful tool for the study of slower ecological and evolutionary processes in still largely unexplored soil microbial communities. They can be used to gain insight into the adaptation of native communities to a specific permanent stress (e.g. soil hypoxia) as long-term natural experimental systems. In this chapter a review of the literature investigating AM fungi and their communities in hypoxic environments is presented. Considering this aspect will be essential for our capacity to adequately manage ecosystems and predict ecological and evolutionary responses to global change, with flooding and soil hypoxia being a consistent part of terrestrial ecosystems in the future.



14 October 2016, two new papers published in Ecological Engineering and Advances in Ecological Research

two new papers have been published in September and October 2016 by me and co-authors.

A paper on remediation and reinoculation of heavy metal contaminated soils with AM fungi in Ecological Engineering, and


a chapter titled ‘Locally Extreme Environments as Natural Long-Term Experiments in Ecology’, in book series Advances in Ecological Research (Academic Press, Oxford).



Many natural phenomena and ecological processes take place extremely slowly, requiring both long-term observations and experiments to investigate them. An alternative is to investigate natural systems that have long-term and stable environmental conditions that are opposed to those of the surrounding ecosystem. Locally extreme environments provide an example of this, and are a powerful tool for the study of slower ecological and evolutionary processes, allowing the investigation of longer term mechanisms at logistically tractable spatial and temporal scales. These systems can be used to gain insight into adaptation of natural communities and their ecological networks. We present a case study and review the literature investigating biological communities at terrestrial mofettes—natural sites with constant geogenic CO2 exhalations and consequent soil hypoxia. Mofettes are often used as natural analogues to future conditions predicted by current climate change scenarios, as model ecosystems for environmental impact assessments of carbon capture and storage systems and for the investigation of physiological, ecological and evolutionary studies of a range of phylogenetically distinct organisms across spatial scales. The scientific power of locally extreme environments is just starting to be harnessed and these systems are bound to provide growing insight into long-term ecological processes, which will be essential for our capacity to adequately manage ecosystems and predict ecological and evolutionary responses to global change.

The Chapter Six can be read HERE.

4 April 2014, SCOPES project approved

SCOPES project (Scientific co-operation between Eastern Europe and Switzerland)

was approved for financing by the Swiss National Science Foundation.

Title: Biodiversity of Arbuscular Mycorrhizal Fungi and its Importance for Sustainable Land-use in Selected Areas of Balkan Peninsula – BALKANAM.

This is a study on diversity, ecology and biogeography of arbuscular mycorrhizal (AM) fungi in selected biodiversity rich areas of Balkan Peninsula. The work is based on concomitant morphological and molecular analyses of the plant roots and fungal spores.

Duration: June 2014 – May 2017.

4 April 2014, Nataša Šibanc’s Ph.D. defense titled ‘Biodiversity of Arbuscular Mycorrhizal Fungi and Selected Groups of Rhizosphere Microorganisms from Natural CO2 Springs’


Nataša Šibanc’s Ph.D. defense titled

Biodiversity of Arbuscular Mycorrhizal Fungi and Selected Groups of Rhizosphere Microorganisms from Natural CO2 Springs

was on Friday, 4 April 2014 at 9 am, at University of Ljubljana Biotechnical Faculty, Jamnikarjeva 101. The defense is open to public.

Natasa doktorat


Understanding the processes that regulate the diversity of soil microorganisms is essential for predicting ecosystem responses to environmental changes. Research in natural ecosystems is difficult to conduct due to the specific characteristics of soil, where selection pressures in soils are rarely temporally and spatially oriented and often tend to overlap with other soil characteristics. Natural CO2 springs (mofettes) are extreme ecosystems, where carbon dioxide (CO2) of geological origin reaches the soil surface resulting in long term changes in soil gas composition. Because CO2 vents through the soil, plant roots and soil organisms are the first to be affected by this CO2 source.

For this study on diversity and ecology of communities of soil microorganisms, species-rich and functionally important groups of soil microbes; arbuscular mycorrhizal (AM) fungi, archaea, bacteria, and yeasts were chosen. The AM fungal community composition from selected mofette areas in Slovenia, Italy and the Czech Republic, was determined using Roche 454 GS-FLX pyrosequencing. The community composition of archaea and bacteria from the area of Slovenian mofettes near Stavešinci village was determined using PCR, cloning and Sanger sequencing. Yeasts from the area of Slovenian mofettes were isolated using several isolation techniques and different growth media and identified using molecular approaches.

The most important environmental factors influencing AM fungal, archaeal, and bacterial community composition from natural CO2 springs are the concentration of CO2 in soil air, hypoxia and soil pH. In addition, we have found that AM fungal community composition was different between the two years of sampling, but no significant compositional changes in AM fungal community were observed among different months, or among geographically distant mofettes. AM fungal communities sampled from control locations showed higher biodiversity (according to Hill’s numbers) while no significant difference in biodiversity of archaea and bacteria among locations with different CO2 concentrations was observed. We have identified eight yeast isolates, including the yeast Occultifur species sp. nov., a new, previously undescribed species.

The results of our study show that the emission of geological gas can have significant ecological consequences arising from the changes in the soil microbial community composition. This is shown by a shift towards a greater abundance of anaerobic and methanogenic archaea and bacteria and higher number of fermentative yeast species and also a permanent changes in community composition of all researched microbial groups towards a greater abundance of ecological specialists.

22 October 2013, two new papers on mofette microbial communities – a research paper in Soil Biology & Biochemistry and a review paper in Acta Agriculturae Slovenica

In October 2013 two papers on mofette microbial communities have been published on-line.

1) A paper by Nataša Šibanc, Alex J. Dumbrell, Ines Mandić-Mulec and Irena Maček in Soil Biology & Biochemistry  titled

Impacts of naturally elevated soil CO2 concentrations on communities of soil archaea and bacteria


There is a limited understanding of the importance of abiotic factors in regulating biodiversity and structure of many functionally important soil microbial communities. In this paper we present a molecular characterisation of archaeal and bacterial communities, exposed to long-term change in soil abiotic environment at natural CO2 springs (mofettes), using T-RFLP profiling and examination of 16S rRNA clone libraries. Our results show major shifts in archaeal and bacterial communities towards anaerobic and methanogenic taxa dominating in CO2 rich hypoxic soils with a significant increase in abundance of Methanomicrobia and predominantly anaerobic Chloroflexi and Firmicutes. O2 concentration in soil was consistently shown to be the strongest predictor of the compositional changes across both the archaeal and bacterial communities. However, soil pH and total N, were most important in separating the archaeal communities in transition and control zones, but not the bacterial communities. We conclude that geological CO2 induced hypoxia in mofette systems can cause major shifts in community composition of soil microbes that can generate significant implications for ecosystem functioning (e.g. nutrient cycling and CH4 production). Our data indicate that mofettes offer a good model system for studying the response of natural microbial communities to long-term environmental changes, which is urgently needed to address the bias towards macro-organisms in soil biodiversity research.

 2)  A review paper in Acta Agriculturae Slovenica (AAS)  by Irena Maček titled

A decade of research in mofette areas has given us new insights into adaptation of soil microorganisms to abiotic stress


A cluster of arbuscular mycorrhizal fungal spores on the cover. Foto: Irena Maček


Natural CO2 springs (mofettes) represent extreme ecosystems with severe exhalations of ambient temperature geological CO2, inducing long-term soil hypoxia. In this paper an overview of mofette research in the fields of microbial ecology and biodiversity in presented, with a focus on the studies describing the impact of the changed soil gas regime on communities of arbuscular mycorrhizal fungi, archaea and bacteria. Along with the fast development of new, high- throughput molecular techniques driving the field of molecular ecology, mofettes enable new insights into the importance of the abiotic environmental factors in regulating soil biodiversity, and the community structure of these functionally important microbial groups.

Contact for reprints: irena.macek@bf.uni-lj.si.