Elisangela Miceli

Plant-endophytes interaction influences the secondary metabolism in Echinacea purpurea (L.) Moench: an in vitro model

The influence of the interaction(s) between the medicinal plant Echinacea purpurea (L.) Moench and its endophytic communities on the production of alkamides is investigated. To mimic the in vivo conditions, we have set up an infection model of axenic in vitro E. purpurea plants inoculated with a pool of bacterial strains isolated from the E. purpurea stems and leaves. Here we show different alkamide levels between control (not-inoculated) and inoculated plants, suggesting that the alkamide biosynthesis may be modulated by the bacterial infection. Then, we have analysed the branched-chain amino acids (BCCA) decarboxylase gene (GenBank Accession #LT593930; the enzymatic source for the amine moiety formation of the alkamides) expression patterns. The expression profile shows a higher expression level in the inoculated E. purpurea tissues than in the control ones. These results suggest that the plant-endophyte interaction can influence plant secondary metabolism affecting the therapeutic properties of E. purpurea.

Phenotypic and genomic characterization of the antimicrobial producer Rheinheimera sp. EpRS3 isolated from the medicinal plant Echinacea purpurea: insights into its biotechnological relevance

In recent years, there has been increasing interest in plant microbiota; however, despite medicinal plant relevance, very little is known about their highly complex endophytic communities. In this work, we report on the genomic and phenotypic characterization of the antimicrobial compound producer Rheinheimera sp. EpRS3, a bacterial strain isolated from the rhizospheric soil of the medicinal plant Echinacea purpurea. In particular, EpRS3 is able to inhibit growth of different bacterial pathogens (Bcc, Acinetobacter baumannii, and Klebsiella pneumoniae) which might be related to the presence of gene clusters involved in the biosynthesis of different types of secondary metabolites. The outcomes presented in this work highlight the fact that the strain possesses huge biotechnological potential; indeed, it also shows antimicrobial effects upon well-described multidrug-resistant (MDR) human pathogens, and it affects plant root elongation and morphology, mimicking indole acetic acid (IAA) action.

Draft Genome Sequences of the Antimicrobial Producers Pseudomonas sp. TAA207 and Pseudomonas sp. TAD18 Isolated from Antarctic Sediments.

ABSTRACT We report here the draft genome sequence of the Pseudomonas sp. TAA207 and Pseudomonas sp. TAD18 strains, isolated from Antarctic sediments during a summer campaign near coastal areas of Terra Nova Bay (Antarctica). Genome sequence knowledge allowed the identification of genes associated with the production of bioactive compounds and antibiotic resistance. Furthermore, it will be instrumental for comparative genomics and the fulfillment of both basic and application-oriented investigations.

Draft Genome Sequence of Pseudomonas sp. EpS/L25, Isolated from the Medicinal Plant Echinacea purpurea and Able To Synthesize Antimicrobial Compounds

ABSTRACT We announce here the draft genome sequence of Pseudomonas sp. strain EpS/L25, isolated from the stem/leaves of the medicinal plant Echinacea purpurea. This genome will allow for comparative genomics in order to identify genes associated with the production of bioactive compounds and antibiotic resistance.

Spatial structuring of bacterial communities in epilithic biofilms in the Acquarossa river (Italy)

Epilithic river biofilms characterize the rock surfaces along the Acquarossa river (Viterbo, Italy); they are in part red and in part black colored, maintaining a well-defined borderline. This peculiarity has raised questions about the biotic and abiotic phenomena that might avoid the mixing of the two biofilms. In this study, the structuring of bacterial communities in black and red epilithic biofilm in the Acquarossa river has been investigated with both culture dependent and independent approaches. Data obtained highlighted a (very) different taxonomic composition of black and red epilithons bacterial communities, dominated by Acinetobacter sp. and iron-oxidizing bacteria, respectively. The chemical characterization of both river water and biofilms revealed a substantial heavy metals pollution of the environment; heavy metals were also differentially accumulated in red and black epilithons. Overall, our data revealed that the structuring of red and black epilithons might be affected mainly by the antagonistic interactions exhibited by bacterial genera dominating the two biofilms. These findings suggest that biotic factors might be responsible for the structuring of natural bacterial communities, suggesting that there is a selection of populations at very small scale, and that different populations might compete for different niches.

Antagonism and antibiotic resistance drive a species-specific plant microbiota differentiation in Echinacea spp.

A key factor in the study of plant-microbes interactions is the composition of plant microbiota, but little is known about the factors determining its functional and taxonomic organization. Here we investigated the possible forces driving the assemblage of bacterial endophytic and rhizospheric communities, isolated from two congeneric medicinal plants, Echinacea purpurea (L.) Moench and Echinacea angustifolia (DC) Heller, grown in the same soil, by analysing bacterial strains (isolated from three different compartments, i.e. rhizospheric soil, roots and stem/leaves) for phenotypic features such as antibiotic resistance, extracellular enzymatic activity, siderophore and indole 3-acetic acid production, as well as cross-antagonistic activities. Data obtained highlighted that bacteria from different plant compartments were characterized by specific antibiotic resistance phenotypes and antibiotic production, suggesting that the bacterial communities themselves could be responsible for structuring their own communities by the production of antimicrobial molecules selecting bacterial-adaptive phenotypes for plant tissue colonization.

New Genome Sequence of an Echinacea purpurea Endophyte, Arthrobacter sp. Strain EpSL27, Able To Inhibit Human-Opportunistic Pathogens

ABSTRACT We announce here the draft genome sequence of Arthrobacter sp. strain EpSL27, isolated from the stem and leaves of the medicinal plant Echinacea purpurea and able to inhibit human-pathogenic bacterial strains. The genome sequencing of this strain may lead to the identification of genes involved in the production of antimicrobial molecules.

Arthrobacter sp. EpRS66 and Arthrobacter sp. EpRS71: Draft Genome Sequences from Two Bacteria Isolated from Echinacea purpurea Rhizospheric Soil

One of the most promising, but still overlooked fields of microbiological research is represented by endophytic microorganisms, i.e., those organisms living in the tissues of host plants and/or in their rhizosphere (Rosenblueth and Martinez-Romero, 2006; Reinhold-Hurek and Hurek, 2011). These microbes are emerging as a new potential source of secondary metabolites and products, for exploitation in medicine, agriculture, and industry. From a biotechnological perspective, a controlled (engineered) colonization of plants tissues by some bacteria may be desirable because of their ability to produce a variety of plant growth promoting (PGP) molecules, spanning from siderophores, nitrogenases, hormones, and so on. In addition, host-microbe interaction confers indirect advantage to the plant, resulting from the inhibition activity exerted by the associated microbial community toward potential pathogens. Moreover, in the field of medicine, there are examples of very well-known molecules derived by endophytes like antibiotics, antimycotics, and anticancer drugs. Also, it is still unknown if plant-associated bacteria may enhance (or be responsible for) some of the effects exerted by the extracts of medicinal plants (essential oils) (Kloepper and Ryu, 2006; Hardoim et al., 2008). In this regard, in October 2012, in Casola Valsenio (Italy), a collection of microorganisms was isolated from both internal tissues and the rhizospheric soil of the medicinal plant Echinacea purpurea, as reported in Chiellini et al. (2014). Among others, two strains sampled from the rhizosphere and belonging to Arthrobacter species were identified, i.e., Arthrobacter sp. EpRS66 and Arthrobacter sp. EpRS71. Based on their antibiotic resistance profile, reported in Mengoni et al. (2014), and on further tests performed on these two strains, they were selected as good candidates for genome sequencing analysis. The last, will constitute a resource to deeply investigate their genomic features and to perform comparative genomics analysis. Moreover, in the aim of new drugs discovery, the genome sequence will facilitate the identification of putative genes responsible for the production of bioactive compounds.