E-Thesis 286 views 119 downloads
Facultative bacterial symbionts from European Orius species: Evidence for an ancestral symbiotic association / XIAORUI CHEN
Swansea University Author: XIAORUI CHEN
DOI (Published version): 10.23889/SUthesis.61749
Abstract
Pest control in agriculture employs diverse strategies, among which the use of predatory insects has steadily increased. The use of several species within the genus Orius in pest control is widely spread, particularly in Mediterranean Europe. The use of predatory insects in pest control in agricultu...
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Swansea
2022
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| Institution: | Swansea University |
| Degree level: | Doctoral |
| Degree name: | Ph.D |
| Supervisor: | Del Sol, Ricardo |
| URI: | https://cronfa.swan.ac.uk/Record/cronfa61749 |
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| Abstract: |
Pest control in agriculture employs diverse strategies, among which the use of predatory insects has steadily increased. The use of several species within the genus Orius in pest control is widely spread, particularly in Mediterranean Europe. The use of predatory insects in pest control in agriculture has spread worldwide and increased significantly, especially in the use of various Orius species. Currently, most studies about Orius species have been focused on the diet manipulation or selective breeding methods to reduce the rearing costs and improve the efficiency, only a few studies were associated to their Wolbachia symbionts. The characterisation and contribution of microbial symbionts to Orius sp. fitness, behaviour, and potential impact on human health has been neglected. Therefore, there is a lack of knowledge regarding Orius’ symbionts such as their taxonomic characterisation, the functions of the symbionts and potential influences on human health. This project was focused on the first comparative genomics report of genome sequences level description of the predominant culturable facultative bacterial symbionts associated with the analyses of draft genomes of facultative symbionts using Next Generation Sequencing (NGS) technique related to five Orius species (Orius laevigatus, Orius niger, Orius pallidicornis, Orius majusculus and Orius albidipennis) and collected from various European countries (Greece, Italy, and Spain). Initially, coxl (COI) based taxonomic classification of the Orius species used was performed, followed by the isolation of culturable bacteria from live insects. The whole genome sequences of the bacterial isolates were generated and assembled into draft genomes using NGS. The isolates of two predominant bacteria belong to Serratia and Leucobacter genera, the third predominant bacteria are most likely to be a new genus within the Erwiniaceae. Orius sp. Serratia isolates genomes are more similar to Serratia sp. SCBI. Pan-genome analysis of Serratia sp. Orius isolates evidenced an open pan-genome, and 279 accessory genes were related to the insect symbiosis trait. Additionally, pan-genome analyses of the Serratia sp. isolates offered clues linking Type VI secretion system effector–immunity proteins from the Tai4 sub-family to the symbiotic lifestyle. These symbionts were found to colonise all the insect specimens tested, which evidenced an ancestral symbiotic association between these bacteria and the genus Orius. Additionally, plasmid sequence analyses suggest sequence exchanges between Serratia sp. Orius isolates and pathogenic Serratia species, which may have implications for food safety and human health. |
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| Keywords: |
Microbiology, bioinformatic, insect symbiont |
| College: |
Faculty of Medicine, Health and Life Sciences |