Responses of the Endophytic Bacterial Communities of Juncus acutus to Pollution With Metals, Emerging Organic Pollutants and to Bioaugmentation With Indigenous Strains

Abstract

Plants and their associated bacteria play a crucial role in constructed wetlands. In this study, the impact of different levels of pollution and bioaugmentation with indigenous strains individually or in consortia was investigated on the composition of the endophytic microbial communities of Juncus acutus. Five treatments were examined and compared in where the wetland plant was exposed to increasing levels of metal pollution (Zn, Ni, Cd) and emerging pollutants (BPA, SMX, CIP), enriched with different combinations of single or mixed endophytic strains. High levels of mixed pollution had a negative effect on alpha diversity indices of the root communities; moreover, the diversity indices were negatively correlated with the increasing metal concentrations. It was demonstrated that the root communities were separated depending on the level of mixed pollution, while the family Sphingomonadaceae exhibited the higher relative abundance within the root endophytic communities from high and low polluted treatments. This study highlights the effects of pollution and inoculation on phytoremediation efficiency based on a better understanding of the plant microbiome community composition.

Advances of native and non-native Antarctic species to in vitro conservation: improvement of disinfection protocols

“…Several authors have reported advances in the development of tissue cultures for these species [12][13][14][15] , including studies that evidenced the differential responses to tissue cultures of different populations of C. quitensis 16,17 . However, the in vitro establishment of these species has been hampered due to endophytic microorganisms [18][19][20][21][22] that develop in the nutritive media once the explants are placed in them. This causes direct and indirect tissue mortality, necrosis, reduced proliferation of roots and shoots and, in some cases, the death of tissues or plants in their entirety 23 .…”

Invasive grass dominance over native forbs is linked to shifts in the bacterial rhizosphere microbiome

“…Still, higher relative abundance of Methylophilaceae was associated with a less negative competitive response in forbs and a more negative response in grasses. Bacteria in this family have been found in soils with high heavy metal content and include microbes critical for heavy metal attenuation and immobilization [73,74]. Members of Methylophilaceae also form tight symbioses with plants [75][76][77] and are even known to promote seed germination and plant growth [76].…”

Comparison of Two Inoculation Methods of Endophytic Bacteria to Enhance Phytodegradation Efficacy of an Aged Petroleum Hydrocarbons Polluted Soil

“…The application of such endophytic bacteria may be more advantageous compared to bioaugmentation with free-living bacteria, as endophytes have a potential to colonize some niches inside an autochthonous community due to their close association with a plant host. It has also been found that genes responsible for biodegradation may transfer from inoculants to native endophytes and thus speed up the removal of contaminants [37,38].…”

“…The Rhizobium sp. 5WK strain was labelled with the enhanced green fluorescent protein (eGFP) as previously described [35][36][37]. The 5WK strain was equipped with the plasmid using a triparental conjugation with Escherichia coli DH5α as a donor strain, and E. coli PRK 2013 as a helper bacterium.…”

“…Images were taken using a Hamamatsu C9100-50 camera (Hamamatsu Photonics K.K., Hamamatsu, Japan). The confocal pictures were analyzed using ImageJ software and Amira 3D visualization software version 6.1.0 (FEI Visualization Sciences Group, Hillsboro, OR, USA) as described previously [36,37].…”