Synthetic bacterial communities for plant growth promotion

PhD ThesisIncreasing food demands have driven the adoption of new global strategies to intensify productivity without relying on heavy chemical treatments. In the last decades, plant-growth promoting rhizobacteria (PGPR) have emerged as potential biofertilisers and biopesticides in agriculture. The overall aim of this study was to research and develop approaches to genetically engineer PGPR to improve their beneficial activities toward the plant partner. A simplified PGPR community, a Bacillus consortium of three strains, was adopted to study the complexity of the interactions occurring within the consortium and the plant microbiome. Firstly, the comparative genomic analysis of the consortium highlighted the unique and shared features responsible for plant promotion, microbial interaction and cooperation among the strains (niche partitioning, organisation in biofilms with cooperative mechanisms of quorum sensing, cell density control and antibiotic detoxification). Flux balance analysis identified cross-feeding interactions among the strains and the metabolic capability of the consortium to provide nitrogen to the plant, transforming it into forms available for plant utilisation. The consortium PGP potential was then investigated in vitro (LEAP mesocosm assay) and in vivo (pot experiment) on the vegetable crop Brassica rapa. These tests show increased plant growth when the strains were inoculated together rather than individually and when the consortium was used as a supplement of the natural bulk soil microbiome. The in silico study and the plant experiments highlighted areas for genetic improvement of the consortium genomes. Lastly, this work describes the development of a conjugation system that could be used to efficiently engineer non-domesticated bacteria and bacterial communities, such as rhizobacteria and plant microbiomes. The system, based on the plasmid pLS20, was developed in Bacillus subtilis 168 and successfully tested on twenty-three wild type Bacillus strains and three rhizobacillus communities. The research presented here provides tools and approaches for the genetic manipulation of rhizobacterial communities, with the ultimate aim of generating sustainable agricultural bioformulations and sheds light on the complex interactions that can occur in a model microbial PGPR consortia

Gender differences in genital lichen sclerosus: data from a multicenter Italian study on 729 consecutive cases

BACKGROUND: Studies specifically conducted to assess gender differences in genital lichen sclerosus (GLS) are not available. This multi- center study aimed to identify possible gender-related differences on GLS clinical features, history and course, through collecting data from a large mixed-sex sample of patients. METHODS: This was a cross-sectional study on 729 subjects (53.8% females, 46.2% males) affected with GLS, consecutively observed within a network of 15 Italian dermatology units. The following information was specifically collected: clinical features and severity of symptoms re- lated to GLS, extragenital involvement, previous therapies, diagnostic suspicion at referral, type of referring physicians, development of genital squamous-cell carcinoma (SCC). RESULTS: Females complained of symptoms more frequent and severe than men; pallor and scarring-sclerosis-atrophy were the most frequent features without gender differences; itching-related signs were more frequent in females than in males as well as extragenital involvement; prior to receiving a definitive diagnosis, females received treatment more frequently than males; 40% of patients were referred with a misdiagnosis; the highest rate of correct suspected diagnosis at referral came from dermatologists than from other physicians; duration of the disease was found to predispose to SCC development. CONCLUSIONS: Our findings highlighted several gender differences on clinical presentation and symptom profile of GLS. In spite of some characteristic features, misdiagnosis at referrals was frequent

Gender differences in genital lichen sclerosus: data from a multicenter Italian study on 729 consecutive cases

BACKGROUND Studies specifically conducted to assess gender differences in genital lichen sclerosus (GLS) are not available. This multicenter study aimed to identify possible gender-related differences on GLS clinical features, history and course, through collecting data from a large mixed-sex sample of patients. METHODS This was a cross-sectional study on 729 subjects (53.8% females, 46.2% males) affected with GLS, consecutively observed within a network of 15 Italian dermatology units. The following information was specifically collected: clinical features and severity of symptoms related to GLS, extragenital involvement, previous therapies, diagnostic suspicion at referral, type of referring physicians, development of genital squamous-cell carcinoma (SCC). RESULTS Females complained of symptoms more frequent and severe than men; pallor and scarring-sclerosis-atrophy were the most frequent features without gender differences; itching- related signs were more frequent in females than in males as well as extragenital involvement; prior to receiving a definitive diagnosis, females received treatment more frequently than males; 40% of patients were referred with a misdiagnosis; the highest rate of correct suspected diagnosis at referral came from dermatologists than from other physicians; duration of the disease was found to predispose to SCC development. CONCLUSIONS Our findings highlighted several gender differences on clinical presentation and symptom profile of GLS. In spite of some characteristic features, misdiagnosis at referrals was frequent