Rhizospheric Bacterial Strain Brevibacterium casei MH8a Colonizes Plant Tissues and Enhances Cd, Zn, Cu Phytoextraction by White Mustard

Abstract

Environmental pollution by heavy metals has become a serious problem in the world. Phytoextraction, which is one of the plant-based technologies, has attracted the most attention for the bioremediation of soils polluted with these contaminants. The aim of this study was to determine whether the multiple-tolerant bacterium, Brevibacterium casei MH8a isolated from the heavy metal-contaminated rhizosphere soil of Sinapis alba L., is able to promote plant growth and enhance Cd, Zn, and Cu uptake by white mustard under laboratory conditions. Additionally, the ability of the rifampicin-resistant spontaneous mutant of MH8a to colonize plant tissues and its mechanisms of plant growth promotion were also examined. In order to assess the ecological consequences of bioaugmentation on autochthonous bacteria, the phospholipid fatty acid (PLFA) analysis was used. The MH8a strain exhibited the ability to produce ammonia, 1-amino-cyclopropane-1-carboxylic acid deaminase, indole 3-acetic acid and HCN but was not able to solubilize inorganic phosphate and produce siderophores. Introduction of MH8a into soil significantly increased S. alba biomass and the accumulation of Cd (208%), Zn (86%), and Cu (39%) in plant shoots in comparison with those grown in non-inoculated soil. Introduced into the soil, MH8a was able to enter the plant and was found in the roots and leaves of inoculated plants thus indicating its endophytic features. PLFA analysis revealed that the MH8a that was introduced into soil had a temporary influence on the structure of the autochthonous bacterial communities. The plant growth-promoting features of the MH8a strain and its ability to enhance the metal uptake by white mustard and its long-term survival in soil as well as its temporary impact on autochthonous microorganisms make the strain a suitable candidate for the promotion of plant growth and the efficiency of phytoextraction.

The abundance of health-associated bacteria is altered in PAH polluted soils—Implications for health in urban areas?

“…The most common method to compare soil remediation in different treatments is to take samples at selected time intervals and compare the measured variables, such as microbial communities, between sampling dates [ 38 , 59 – 61 ]. As the rate of soil remediation is dependent on soil type, it is conceivable that only the time-dependent changes are reported or noticed, and the microbial community changes connected to actual degradation are ignored.…”

Community Structure, Species Variation, and Potential Functions of Rhizosphere-Associated Bacteria of Different Winter Wheat (Triticum aestivum) Cultivars

“…Many of these interactions are mutualistic. For example, plants benefit from mobilization of minerals ( Vangronsveld et al, 2009 ; Sessitsch et al, 2013 ; Plociniczak et al, 2016 ) and other inorganic molecules, while the microbes benefit from root exudates which provide an energy source in the form of sugars and organic acids ( Bais et al, 2006 ; van Dam and Bouwmeester, 2016 ). Plant hosts further benefit from microbes with improved growth ( Bashan et al, 2014 ; Glick, 2014 ), drought and salt tolerance ( Castiglioni et al, 2008 ; Kasim et al, 2013 ; Han et al, 2014 ; Naveed et al, 2014 ; Sarma and Saikia, 2014 ; Pinedo et al, 2015 ), and protection against soilborne pathogens ( Weller et al, 2002 ; Cha et al, 2015 ; De Boer et al, 2015 ).…”

Screening and Evaluation of the Bioremediation Potential of Cu/Zn-Resistant, Autochthonous Acinetobacter sp. FQ-44 from Sonchus oleraceus L.

“…JYX10 significantly improved Zn uptake by B. napus . Recently, Płociniczak et al (2016) also reported that Brevibacterium casei MH8a colonized white mustard plant tissues and enhanced Cu and Zn phytoextraction.…”

“…Despite numerous reports about rhizobacteria-enhanced phytoremediation of heavy metals ( Sheng and Xia, 2006 ; Dell’Amico et al, 2008 ; Płociniczak et al, 2016 ), little information is available about effects Cu/Zn-resistant bacteria from the rhizosphere of S. oleraceus on plant growth and heavy metal bioavailability/biosorption in multi-metal-polluted soils. Thus, the quest for novel, beneficial and indigenous rhizobacteria among different plant species grown in multi-metal-polluted environments is very meaningful.…”