Abiotic stress resistance, plant growth promotion and antifungal potential of halotolerant bacteria from a Tunisian solar saltern

Authors: MASMOUDI, FATMA - Center Of Biotechnology Of Sfax; Dunlap, Christopher; TRIGUI, MOHAMED - Center Of Biotechnology Of Sfax; ABEDLMALEK, NOUHA - Center Of Biotechnology Of Sfax; TOUNSI, SLIM - Center Of Biotechnology Of Sfax

Submitted to: Microbiological Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/6/2019
Publication Date: 9/8/2019
Citation: Masmoudi, F., Abdelmalek, N., Tounsi, S., Dunlap, C.A., Trigui, M. 2019. Abiotic stress resistance, plant growth promotion and antifungal potential of halotolerant bacteria from a Tunisian solar saltern. Microbiological Research. 229:126331. https://doi.org/10.1016/j.micres.2019.126331.
DOI: https://doi.org/10.1016/j.micres.2019.126331

Interpretive Summary: An ARS researcher from Peoria, IL collaborated with scientists from Sfax University Hospital in Sfax, Tunisia to characterize novel bacteria isolated from a high salt environment. These strains were isolated from a high salt environment with the expectation they would be able to tolerate higher salt stress and heavy metal stress found in irrigated agriculture soils. The strains were assayed and determined to possess strong antifungal activity against a variety of plant pathogens. Preliminary greenhouse trials with tomato plants showed some strains possessed plant growth promotion ability. Further studies are needed to determine if the strain have commercial plant protection properties. This research benefits US farmer and consumers through the development of new crop protection strategies.

Technical Abstract: The use of halotolerant bacteria isolated from naturally saline habitats have the potential to be useful crop protection agents for plants in stressful conditions. These beneficial microbes generate several plant growth regulators and bioactive molecules, which enhance plant protection from adversities, such as plant pathogens, salts and metals stresses. In this study, 15 halophilic and halotolerant bacterial strains endowed with important antimicrobial activities were isolated from Sfax solar saltern (Tunisia). All of these strains were characterized by biochemical and molecular tools aiming to investigate their in-vitro and in-vivo antifungal potentialities, plant growth promotion capabilities and metal tolerance abilities under saline stress condition. The 16S rRNA gene sequencing showed that the isolated strains were affiliated to different phylum and three species were described for the first time as plant growth promoting strains (Idiomarina zobelli FMH6v, Nesterenkonia halotolerans FMH10 and Halomonas janggokensis FMH54). The tested strains exhibited several potentialities: to tolerate high salt and heavy metals concentrations, to produce biosurfactants, EPS and extracellular hydrolytic enzymes, to form biofilms and to liberate plant promoting substances. Eight strains demonstrated the ability to protect tomatoes fruits from the proliferation of the grey mold disease and six strains showed an amelioration of plant vigor indexes. Principal component analysis showed an important correlation between in-vitro and in-vivo potentialities and two strains Bacillus velezensis FMH2 and Bacillus subtilis FMH45 were statistically considered as the most effective strains in protecting plants from fungal pathogens and promoting the growth of tomatoes seedlings under saline and multi heavy-metals stress conditions.