title: Investigating the lignocellulolytic gut microbiome of huhu grubs

authors: Payyakkal Viswam, Jayadev

subjects: Gut microbiome

abstract: New Zealand’s endemic longhorned beetle (Prionoplus reticularis) larvae, huhu grub, are xylophagous and feed on a broad range of dead trees. Since insects are not believed to have the ability to fully degrade lignocellulose, it is likely that microbes present in the gut assist in degrading lignocellulose to release energy rich sugars. This process is considered the rate limiting step in the utilisation of woody material in biofuel production. To better understand the gut consortium present while feeding on the lignocellulose and cellulose components, huhu grubs were initially collected and reared on non-degraded pine blocks (lignocellulose) or cotton (cellulose). The gut fungal and bacterial community of huhu grubs was investigated using high-throughput sequencing and analysis techniques. Furthermore, the effects of a dietary switch on both fungal and bacterial communities was explored by switching huhu grubs initially reared on pine to cotton, and vice versa. Cellulose- and lignocellulose-reared huhu grubs were expected to host a wide range of bacteria and fungi in their gut, some of which produce lignocellulose degrading enzymes. Assessment of the gut fungal community composition confirmed that cellulose-reared huhu grubs were significantly distinct from lignocellulose-reared grubs. The fungal community of lignocellulose-fed huhu grubs was more functionally diverse, with several yeasts, soft-rot fungi and potential hemicellulose and cellulose degraders present. Whereas, the fungal community of cellulose-reared grubs was mostly abundant in yeasts and potential cellulose degraders. When cotton-reared grubs where switched to pine (lignocellulose), lignocellulose was observed to have a ‘bottleneck effect’ or selective pressure on the fungal gut community. The gut bacterial community of huhu grubs reared on cellulose or lignocellulose diets seemed to be unaffected by the selective pressure of the diet, and no significant change in the bacterial community was observed following dietary switch. Therefore it was concluded that the bacterial community while still important is playing a secondary role to the fungi. Finally, bioprospecting studies conducted using the frass (excretia) of these huhu grubs resulted in the isolation of a bacterium, Acinetobacter H23, capable of producing an extracellular laccase. Overall, the increased understanding of structure and composition of the gut microbiome of huhu grubs reared on cellulose or lignocellulose diets, along with isolation of novel lignocellulolytic isolates could prove to be significant for the biofuel industry.

text: Investigating the lignocellulolytic gut microbiome of huhu grubs New Zealand’s endemic longhorned beetle (Prionoplus reticularis) larvae, huhu grub, are xylophagous and feed on a broad range of dead trees. Since insects are not believed to have the ability to fully degrade lignocellulose, it is likely that microbes present in the gut assist in degrading lignocellulose to release energy rich sugars. This process is considered the rate limiting step in the utilisation of woody material in biofuel production. To better understand the gut consortium present while feeding on the lignocellulose and cellulose components, huhu grubs were initially collected and reared on non-degraded pine blocks (lignocellulose) or cotton (cellulose). The gut fungal and bacterial community of huhu grubs was investigated using high-throughput sequencing and analysis techniques. Furthermore, the effects of a dietary switch on both fungal and bacterial communities was explored by switching huhu grubs initially reared on pine to cotton, and vice versa. Cellulose- and lignocellulose-reared huhu grubs were expected to host a wide range of bacteria and fungi in their gut, some of which produce lignocellulose degrading enzymes. Assessment of the gut fungal community composition confirmed that cellulose-reared huhu grubs were significantly distinct from lignocellulose-reared grubs. The fungal community of lignocellulose-fed huhu grubs was more functionally diverse, with several yeasts, soft-rot fungi and potential hemicellulose and cellulose degraders present. Whereas, the fungal community of cellulose-reared grubs was mostly abundant in yeasts and potential cellulose degraders. When cotton-reared grubs where switched to pine (lignocellulose), lignocellulose was observed to have a ‘bottleneck effect’ or selective pressure on the fungal gut community. The gut bacterial community of huhu grubs reared on cellulose or lignocellulose diets seemed to be unaffected by the selective pressure of the diet, and no significant change in the bacterial community was observed following dietary switch. Therefore it was concluded that the bacterial community while still important is playing a secondary role to the fungi. Finally, bioprospecting studies conducted using the frass (excretia) of these huhu grubs resulted in the isolation of a bacterium, Acinetobacter H23, capable of producing an extracellular laccase. Overall, the increased understanding of structure and composition of the gut microbiome of huhu grubs reared on cellulose or lignocellulose diets, along with isolation of novel lignocellulolytic isolates could prove to be significant for the biofuel industry.

year: 2016

title: Busting myths on water weeds

authors: de Winton, Mary

abstract: Troublesome aquatic weeds have been an issue for the Rotorua Te Arawa Lakes for decades, but what do we really know about what drives water weed problems? Some common held beliefs about water weeds are ‘one weed is as bad as another’, ‘waterfowl move water weeds around’ and ’nutrient enrichment drives weed invasion’. However, these assumptions are incorrect or represent an oversimplified view of the problem. Exploring these popular misconceptions on water weeds will help us get a better understanding of weed problems, the role of humans and what we can do about it. This talk will draw evidence from New Zealand and international research findings and
information specific to the Rotorua Te Arawa Lakes.
Weed issues for the Rotorua Te Arawa Lakes involve just a few species of alien plant species that share characteristics including a high ‘standing crop’ (bulk biomass present at any one time), dense canopy at, or close to the water surface and generation of numerous fragments that can accumulate onshore. Nevertheless, these few species can be further distinguished and ranked in terms of ‘weediness’ and impact. Recognition that some weeds are worse than others allows for more effective and proactive management of
weed threats.
Water fowl are often implicated in spreading the most problematic water weeds that we have in New Zealand and yet there little real evidence that this is the case. Instead there is ample evidence that human activities are primarily responsible for the spread of water weeds between lake catchments. This means that it should be possible to intercept the routes and mechanisms (pathways and vectors) by which these water weeds can enter lakes.
Weed invasions in freshwater systems are suggested to be linked with nutrient enrichment. However, the presence of our worst water weeds and the development of weed-related problems are not limited to eutrophied lakes, but can be equally problematic in oligotrophic New Zealand lakes. Indeed, the most enriched lake systems have very limited submerged vegetation development. Therefore improving water quality does not necessarily flow on to the anticipated improvements in weed problems and there may even be increased weed development as lakes become less enriched.

text: Busting myths on water weeds Troublesome aquatic weeds have been an issue for the Rotorua Te Arawa Lakes for decades, but what do we really know about what drives water weed problems? Some common held beliefs about water weeds are ‘one weed is as bad as another’, ‘waterfowl move water weeds around’ and ’nutrient enrichment drives weed invasion’. However, these assumptions are incorrect or represent an oversimplified view of the problem. Exploring these popular misconceptions on water weeds will help us get a better understanding of weed problems, the role of humans and what we can do about it. This talk will draw evidence from New Zealand and international research findings and
information specific to the Rotorua Te Arawa Lakes.
Weed issues for the Rotorua Te Arawa Lakes involve just a few species of alien plant species that share characteristics including a high ‘standing crop’ (bulk biomass present at any one time), dense canopy at, or close to the water surface and generation of numerous fragments that can accumulate onshore. Nevertheless, these few species can be further distinguished and ranked in terms of ‘weediness’ and impact. Recognition that some weeds are worse than others allows for more effective and proactive management of
weed threats.
Water fowl are often implicated in spreading the most problematic water weeds that we have in New Zealand and yet there little real evidence that this is the case. Instead there is ample evidence that human activities are primarily responsible for the spread of water weeds between lake catchments. This means that it should be possible to intercept the routes and mechanisms (pathways and vectors) by which these water weeds can enter lakes.
Weed invasions in freshwater systems are suggested to be linked with nutrient enrichment. However, the presence of our worst water weeds and the development of weed-related problems are not limited to eutrophied lakes, but can be equally problematic in oligotrophic New Zealand lakes. Indeed, the most enriched lake systems have very limited submerged vegetation development. Therefore improving water quality does not necessarily flow on to the anticipated improvements in weed problems and there may even be increased weed development as lakes become less enriched.

year: 2015

title: A new beginning for indigenous wellbeing - Guest editorial

authors: Nikora, Linda Waimarie

abstract: Three members of the editorial board of the Journal of Indigenous Wellbeing – Te Mauri: Pimatisiwin and the Editor reflect on the genesis of the journal, comment on its journey over time, review its mission moving forward and introduces the first edition of the journal August 2016. The authors of this article include the current editorial board’s chairperson, two board members – one a past editor of the journal, the other, the journal’s present patron and the current editor.

text: A new beginning for indigenous wellbeing - Guest editorial Three members of the editorial board of the Journal of Indigenous Wellbeing – Te Mauri: Pimatisiwin and the Editor reflect on the genesis of the journal, comment on its journey over time, review its mission moving forward and introduces the first edition of the journal August 2016. The authors of this article include the current editorial board’s chairperson, two board members – one a past editor of the journal, the other, the journal’s present patron and the current editor.

year: 2016