Evolution of mutualistic behaviour between chlorella sorokiniana and saccharomyces cerevisiae within a synthetic environment.
| dc.contributor.advisor | Bauer, Florian | en_ZA |
| dc.contributor.advisor | Naidoo-Blassoples, Rene Kathleen | en_ZA |
| dc.contributor.advisor | Rossouw, Debra | en_ZA |
| dc.contributor.author | Oosthuizen, Jennifer Rae | en_ZA |
| dc.contributor.other | Stellenbosch University. Faculty of AgriSciences. Dept. of Viticulture and Oenology. Institute for Wine Biotechnology. | en_ZA |
| dc.date.accessioned | 2020-11-30T21:18:05Z | |
| dc.date.accessioned | 2021-02-01T07:56:09Z | |
| dc.date.available | 2020-11-30T21:18:05Z | |
| dc.date.available | 2021-02-01T07:56:09Z | |
| dc.date.issued | 2020-12 | |
| dc.description | Thesis (MScAgric)--Stellenbosch University, 2020. | en_ZA |
| dc.description.abstract | ENGLISH ABSTRACT: Microbial symbioses are abundant in the natural environment. Mutualisms are a subset of these symbioses that still lack fundamental understanding regarding the manner in which these complex interactions form and alter microbial species over time. Phototrophic-heterotrophic microbial systems are becoming more commonplace in research due to the many benefits they can provide when different organisms are combined. Heterotrophic fungal systems are largely utilized in the production of high-value metabolites, while phototrophic microalgal systems are found primarily in the green sector such as carbon dioxide sequestration or biofuel production. Synthetic ecology implemented into thoughtfully designed artificial ecosystems provides an ideal method for both the fundamental study of mutualistic symbioses and the production of improved microbial strains for industry. Both the long- and short-term effects of microbial co-evolution on strain performance are largely unknown. Mutualistic interactions are a way to study these effects as the nature of the interaction, reliance on the survival of a partner species, prevents a single species from outcompeting the other. The clear benefits of mutualistic interactions for industrial applications, such as increased growth of both species and/or the production of novel metabolites, also provide clear incentives to investigate these interactions. This study employed synthetic ecology principles and designed an artificial ecosystem to investigate the effects of co-evolution on a mutualistic yeast-microalgal pairing. The yeast, Saccharomyces cerevisiae, and microalga, Chlorella sorokiniana, were co-evolved in an environment that imposed an obligate mutualism between the two microbial partners for approximately 100 generations. The obligate mutualistic interaction was based upon the reciprocal exchange of carbon (CO2 from S. cerevisiae) and nitrogen (ammonia from C. sorokiniana). Strains were isolated from the 50th and 100th generation for further phenotypic, metabolic and transcriptional analysis compared to the parental strains. Phenotypic screening of isolates took place in both mono- and co-culture (multiple pairwise combinations of evolved yeast and microalgae) with various carbon and nitrogen sources to test the limits and effects of co-evolution. This study clearly demonstrated how even short periods of co-evolution can cause changes to the phenotypic growth and metabolite usage of co-evolved isolates. All co-evolved yeast and microalgal strains showed changes to growth rate and a wide variety of growth patterns when compared to the parental strains. Importantly, changes in the expression of key carbon and nitrogen genes were also observed in the evolved isolates of both species. These observed changes assist in highlighting potential underlying mechanisms that occur during co-evolution. These results, when taken together show that even short periods of co-evolution, can produce strains with different characteristics to the parental strains. Harnessing techniques such as co-evolution in combination with synthetic ecology and artificial ecosystems will allow for the creation of functional ecosystems with applications in a wide variety of sustainable industries such as the bioremediation, carbon capture and biofuel industries. | en_ZA |
| dc.description.abstract | AFRIKAANSE OPSOMMING: Mikrobiese simbiose is ‘n algemene verskynsel in die natuurlike omgewing. Mutualismes is 'n onderafdeling van hierdie mikrobiese simbiose. Daar is nog nie 'n fundamentele begrip van die manier waarop mikrobiese spesies deur hierdie komplekse interaksies oor tyd gevorm en verander word nie. Fototrofiese-heterotrofiese mikrobiese stelsels word meer algemeen in navorsing aangetref weens die vele voordele wat hierdie stelsels kan bied wanneer verskillende organismes bymekaargevoeg word. Heterotrofiese swamsisteme word grotendeels in die produksie van hoë waarde metaboliete gebruik, terwyl fototrofiese mikroalgale stelsels hoofsaaklik in die groen ekonomiese sektor voorkom. ‘n Voorbeeld is koolstofdioksied-sekwestrasie of die produksie van biobrandstof. Sintetiese ekologie wat in goed-ontwerpte kunsmatige ekosisteme geïmplementeer word, voorsien 'n ideale metode vir beide die fundamentele studie van mutualistiese simbiose en die produksie van verbeterde mikrobiese stamme vir die industrie. Beide die lang- en korttermyn-effekte van mikrobiese ko-evolusie op die werkverrigting van die mikrobiese stam is grotendeels onbekend. Mutualistiese interaksies is 'n manier om hierdie effekte te bestudeer, aangesien die aard van die interaksie, afhanklikheid van die oorlewing van 'n simbiotiese spesie, verhoed dat 'n enkele spesie die ander domineer. Die voor die hand liggende voordele van mutualistiese interaksies vir industriële toepassings, soos verhoogde groei van beide spesies of / en die produksie van nuwe metaboliete, bied ook duidelike motivering om hierdie interaksies te ondersoek. Hierdie studie het sintetiese ekologiese beginsels gebruik en 'n kunsmatige ekosisteem ontwerp om die gevolge van ko-evolusie op 'n mutualistiese gis-mikroalgale paring te ondersoek. Die gis, Saccharomyces cerevisiae, en mikroalga, Chlorella sorokiniana, is saam ontwikkel in 'n omgewing wat vir ongeveer 100 geslagte 'n verpligte wedersydse werking tussen die twee mikrobiese stamme opgelê het. Die verpligte onderlinge interaksie was gebaseer op die wederkerige uitruiling van koolstof (CO2 van S. cerevisiae) en stikstof (ammoniak van C. sorokiniana). Stamme is geïsoleer vanaf die 50ste en 100ste generasie vir verdere fenotipiese, metaboliese en transkripsionele analise in vergelyking met die oospronklike stamme. Fenotipiese sifting van isolate het plaasgevind in beide mono- en mede-kweek (meervoudige paargewyse kombinasies van ontwikkelde gis en mikroalge) met verskillende koolstof- en stikstofbronne om die grense en effekte van mede-evolusie te toets. Hierdie studie het duidelik getoon hoe selfs kort periodes van ko-evolusie veranderinge kan meebring in die fenotipiese groei en metabolietgebruik van saam-ontwikkelde isolate. Alle gis- en mikroalgale stamme wat saam ontwikkel het, het veranderings in die groeikoers en 'n wye verskeidenheid groeipatrone getoon in vergelyking met die oorspronklike stamme. Dit is belangrik dat veranderinge in belangrike koolstof- en stikstofgene ook in die geïsoleerde isolate van beide spesies waargeneem is. Hierdie waarnemings help om potensiële onderliggende meganismes wat tydens ko-evolusie voorkom, uit te lig. Saam toon hierdie resultate dat selfs kort periodes van ko-evolusie stamme met verskillende eienskappe as die ouerstamme kan lewer. Deur tegnieke soos ko-evolusie in kombinasie met sintetiese ekologie en kunsmatige ekosisteme te gebruik, kan funksionele ekosisteme geskep word met toepassings in 'n wye verskeidenheid volhoubare nywerhede, soos die bioremediasie-, koolstofopvang- en biobrandstofbedryf. | af_ZA |
| dc.description.version | Masters | en_ZA |
| dc.embargo.terms | 2021-12-31 | |
| dc.format.extent | 92 pages : illustrations (some color) | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/10019.1/109461 | |
| dc.language.iso | en_ZA | en_ZA |
| dc.publisher | Stellenbosch : Stellenbosch University | en_ZA |
| dc.rights.holder | Stellenbosch University | en_ZA |
| dc.subject | Co-evolution | en_ZA |
| dc.subject | Mutualism | en_ZA |
| dc.subject | Cross-feeding | en_ZA |
| dc.subject | Saccharomyces cerevisiae -- Effect of stress on | en_ZA |
| dc.subject | Chlorella sorokiniana | en_ZA |
| dc.subject | Yeast interaction | en_ZA |
| dc.subject | UCTD | en_ZA |
| dc.title | Evolution of mutualistic behaviour between chlorella sorokiniana and saccharomyces cerevisiae within a synthetic environment. | en_ZA |
| dc.type | Thesis | en_ZA |