Drivers of gut microbiome diversity in commercially mass-reared black soldier flies
| dc.contributor.advisor | Rhode, Clint | en_ZA |
| dc.contributor.author | Greenwood, Matthew Peter | en_ZA |
| dc.contributor.other | Stellenbosch University. Faculty of AgriSciences. Dept. of Genetics. | en_ZA |
| dc.date.accessioned | 2021-11-09T16:47:46Z | |
| dc.date.accessioned | 2021-12-22T14:19:43Z | |
| dc.date.available | 2021-11-09T16:47:46Z | |
| dc.date.available | 2021-12-22T14:19:43Z | |
| dc.date.issued | 2021-12 | |
| dc.description | Thesis (MScAgric)--Stellenbosch University, 2021. | en_ZA |
| dc.description.abstract | ENGLISH ABSTRACT: The black soldier fly, Hermetia illucens, is a focal species for industrial and commercial mass-rearing owing to the ability of its larvae to convert large quantities of organic waste material into high-value protein, lipid, and chitin biomass. Recent studies have indicated that specific gut bacteria can modulate the bioconversion potential of H. illucens larvae. In turn, it is increasingly recognised that information regarding the diversity and composition of larval gut microbial communities (i.e., the microbiome) may be valuable for the prediction, directed improvement, and maintenance of phenotypic performance in these rearing systems. However, the development of strategies to effectively exploit microbiome data in practice will rely on understanding of the factors that dictate microbiome establishment, persistence, identity, and function. Therefore, the aim of this study was to determine the extent to which environmental and host genetic variation shape H. illucens gut microbial communities and, consequently, impact relationships between the microbiome and economically important larval traits. To disentangle the effects of host genetics and environment on microbiome establishment, larvae from two different strains were reared on four feed substrates in a crossed experimental design under otherwise controlled conditions. The gut bacterial communities of larvae were profiled using a 16S rDNA next-generation sequencing approach. Between-group comparisons of gut microbial diversity and composition revealed significant effects of diet, host genetic background, and an interaction between these factors on microbiome establishment. Moreover, by inferring the metabolic profiles of gut communities, it was demonstrated that the effects of diet likely drive microbiome divergence at the functional level. Correlation and variance partitioning analyses supported a subsequent impact of microbiome divergence on the fat and protein accumulation rates of larvae and suggested that the influence of diet on gut microbial communities was most relevant to phenotypic outcomes. Recognising that further interactions between immunity-related host gene expression patterns and diet may be implicated in shaping microbiome profile divergence, the transcriptional activity of two larval antimicrobial peptide genes was also assessed. Expression patterns for one of these genes, a cecropin-like peptide factor, was both affected by diet and significantly associated with differentiation in microbiome composition between larval groups. Together, these results are largely concordant with findings in other model systems and demonstrate that complex interactions between host regulatory networks and environmental variation shapes the diversity, identity, and functional capacity of the H. illucens microbiome. In resolving putative microbiome- trait effects associated with change in larval gut microbial profiles, this work indicates that black soldier fly biology and microbial ecology are tightly intertwined, and bolsters prior suggestions that knowledge of larval microbiome constitutes a viable avenue for phenotypic improvement in industry. | en_ZA |
| dc.description.abstract | AFRIKAANSE OPSOMMING: Die venstervlieg, Hermetia illucens, is 'n fokusspesie vir industriële en kommersiële massa- produksie omdat die larwes die vermoë het om groot hoeveelhede organiese afvalmateriaal te omskep in proteïen-, lipied- en chitienbiomassa wat 'n hoë waarde het. Onlangse studies dui aan dat spesifieke dermbakterieë die bio-omskakelingspotensiaal van H. illucens larwes kan moduleer. Dit word toenemend erken dat inligting rakende die diversiteit en samestelling van die mikrobiese gemeenskappe van die larwe (die mikrobioom) waardevol kan wees vir die voorspelling, gerigte verbetering en instandhouding van fenotipiese prestasie in hierdie produksiestelsel. Die ontwikkeling van strategieë om mikrobioomdata in die praktyk effektief te benut, sal egter afhang van die begrip van die faktore wat die vestiging, volharding, identiteit en funksie van die mikrobioom bepaal. Daarom was die doel van hierdie studie om te bepaal tot watter mate omgewings- en gasheer-genetiese variasie die derm-mikrobiese gemeenskappe vorm en hoe hierdie faktore die verhoudings tussen die mikrobioom en ekonomies belangrike larwe- eienskappe beïnvloed. Die effek van gasheergenetika en die omgewing op die vestiging van die mikrobioom was evalueer deur om vier voedselsubstrate vir larwes, wat van twee verskillende stamme geproduseer was, te voer in 'n gekruiste eksperimentele ontwerp onder beheerde toestande. Die dermbakteriële gemeenskappe van larwes was geassesseer deur middel van 'n 16S rDNA metagenomiese benadering. Tussen-groep vergelykings van derm mikrobiese diversiteit en samestelling het gewys dat dieet, gasheer-genetiese agtergrond en 'n interaksie tussen hierdie faktore beduidende gevolge op die vestiging van die mikrobioom het. Die metaboliese profiele van die derm-mikrobiese gemeenskappe, het gewys dat dieet waarskynlik mikrobioom-afwyking op ‘n funksionele vlak kan veroorsaak. Korrelasie- en afwykingsverdelings analiese ondersteun dat 'n mikrobioom-afwyking ‘n impak het op die vet- en proteïenakkumulasie van larwes en dat die invloed van dieet op derm mikrobiese gemeenskappe die mees relevante vir fenotipiese uitkomste was. Die mikrobioomprofiel kan ook beïnvloed word deur interaksies tussen immuniteitsverwante geen gasheeruitdrukkingspatrone en dieet, en daarom was die transkripsionele aktiwiteit van twee larwe-antimikrobiese peptiedgene ook geëvalueer in hierdie studie. Uitdrukkingspatrone vir een van hierdie gene, 'n cecropin-agtige peptiedfaktor, was beïnvloed deur dieet en was beduidend geassosieer met differensiasie in die samestelling van die mikrobioom tussen larwegroepe. Hierdie resultate stem grootliks ooreen met ander modelstelsels en dui aan dat komplekse interaksies tussen gasheerregulerende netwerke en omgewingsvariasie die diversiteit, identiteit en funksionele kapasiteit van die H. illucens-mikrobioom vorm. Hierdie studie het gewys dat die biologie van venstervlieë en mikrobiese ekologie verweef is deur die assessering van mikrobiome-eienskapseffekte wat verband hou met veranderinge in die mikrobiese profiele van larwe, en daarom versterk hierdie studie dat larwe-mikrobioom fenotipiese kennis verbetering in die industrie kan handhaaf. | af_ZA |
| dc.description.version | Masters | en_ZA |
| dc.format.extent | xviii, 126 pages : illustrations (some color) | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/10019.1/123757 | |
| dc.language.iso | en_ZA | en_ZA |
| dc.publisher | Stellenbosch : Stellenbosch University | en_ZA |
| dc.rights.holder | Stellenbosch University | en_ZA |
| dc.subject | Black soldier fly (Hermetia illucens)larvae -- Nutrient value | en_ZA |
| dc.subject | Gut microbiome | en_ZA |
| dc.subject | 16S rDNA | en_ZA |
| dc.subject | Mass rearing of insects | en_ZA |
| dc.subject | Flies -- Larvae -- Economic aspects | en_ZA |
| dc.subject | Antimicrobial peptide | en_ZA |
| dc.subject | Organic wastes -- Biodegradation | en_ZA |
| dc.subject | UCTD | en_ZA |
| dc.title | Drivers of gut microbiome diversity in commercially mass-reared black soldier flies | en_ZA |
| dc.type | Thesis | en_ZA |