Biology subjects

Oso, S.

Publications and source records attributed to Oso, S..

3 recordsLinked to original sources

bioRxiv2025

Comparative genomics of epiphytic and endophytic bacterial culture collections from Arabidopsis thaliana in Otautahi (Christchurch), Aotearoa New Zealand

Bacterial culture collections are essential resources for exploring the diversity of microorganisms and their interactions with each other and their hosts. Here, we report on the sequencing of the first 129 bacterial isolates, representing 34 genera, from a culture collection of more than 600 bacterial strains originally isolated from leaves of a naturalised Arabidopsis thaliana population from [O]tautahi (Christchurch), Aotearoa New Zealand. Epiphytic (leaf surface), and endophytic (apoplastic) bacteria were isolated separately from the same leaves, providing complementary insights into both compartments. The recovered isolates encompass the dominant taxa typically associated with the Arabidopsis phyllosphere, including Pseudomonas, Sphingomonas, Methylobacterium, and Flavobacterium. Their full genome assemblies (BUSCO average completeness > 99%, checkM average completeness > 97% and average contamination < 1%) were analysed and compared to assess genomic features across epiphytic and endophytic lineages. While the epiphytic and endophytic strain collections did not show large genomic differences, certain functional categories differ, such as terpene biosynthesis and biofilm formation being enriched in epiphytic strains, while arginine biosynthesis and carbohydrate degradation were associated with endophytic strains. These data provide a genomic foundation for future experimental work on leaf-associated microbial ecology and plant-microbe interactions. To our knowledge, this is the first Arabidopsis leaf culture collection established from a Southern Hemisphere source.

microbiology↗

bioRxiv2020

Characterisation of the biosurfactants from phyllosphere colonising Pseudomonads and their effect on plant colonisation and diesel degradation

Biosurfactant production is a common trait in leaf surface colonising bacteria that has been associated with increased survival and movement on leaves. At the same time the ability to degrade aliphatics is common in biosurfactant-producing leaf colonisers. Pseudomonads are common leaf colonisers and have been recognised for their ability to produce biosurfactants and degrade aliphatic compounds. In this study, we have investigated the role of biosurfactants in four non-plant plant pathogenic Pseudomonas strains by performing a series of experiments to characterise the surfactant properties, and their role during leaf colonisation and diesel degradation. The produced biosurfactants were identified using mass-spectrometry. Two strains produced viscosin-like biosurfactants and the other two produced Massetolide A-like biosurfactants which aligned with the phylogenetic relatedness between the strains. To further investigate the role of surfactant production, random Tn5 transposon mutagenesis was performed to generate knockout mutants. The knockout mutants were compared to their respective wildtypes in their ability to colonise gnotobiotic Arabidopsis thaliana and to degrade diesel. It was not possible to detect negative effects during plant colonisation in direct competition or individual colonisation experiments. When grown on diesel, knockout mutants grew significantly slower compared to their respective wildtypes. By adding isolated wildtype biosurfactants it was possible to complement the growth of the knockout mutants. ImportanceMany leaf colonising bacteria produce surfactants and are able to degrade aliphatic compounds, however, if surfactant production provides a competitive advantage during leaf colonisation is unclear. Furthermore, it is unclear if leaf colonisers take advantage of the aliphatic compounds that constitute the leaf cuticle and cuticular waxes. Here we test the effect of surfactant production on leaf colonisation and demonstrate that the lack of surfactant production decreases the ability to degrade aliphatic compounds. This indicates that leaf surface dwelling, surfactant producing bacteria contribute to degradation of environmental hydrocarbons and may be able to utilise leaf surface waxes. This has implications for plant-microbe interactions and future studies.

microbiology↗

bioRxiv2018

Chromatic Bacteria - A broad host-range plasmid and chromosomal insertion toolbox for fluorescent protein expression in bacteria

Differential fluorescent labelling of bacteria has become instrumental for many aspects of microbiological research, such as the study of biofilm formation, bacterial individuality, evolution, and bacterial behaviour in complex environments. We designed a variety of plasmids, each bearing one of eight unique, constitutively expressed fluorescent protein genes in conjunction with one of four different antibiotic resistance combinations. The fluorophores mTagBFP2, mTurquoise2, sGFP2, mClover3, sYFP2, mOrange2, mScarlet-I, and mCardinal, encoding for blue, cyan, green, green-yellow, yellow, orange, red, and far-red fluorescent proteins, respectively, were combined with selectable markers conferring tetracycline, gentamicin, kanamycin, and/or chloramphenicol resistance. These constructs were cloned into three different plasmid backbones: a broad host-range plasmid, a Tn5 transposon delivery plasmid, and a Tn7 transposon delivery plasmid. The utility of the plasmids and transposons was tested in bacteria from the phyla Actinobacteria, Proteobacteria, and Bacteroidetes. We were able to tag representatives from the phylum Proteobacteria at least via our Tn5 transposon delivery system. The here constructed plasmids are available to the community and provide a valuable tool to investigate bacteria-bacteria, bacteria-host, and bacteria-environmental interactions.

microbiology↗