title: Exploring rumen microbe-derived fibre-degrading activities for improving feed digestibility

authors: Moon, Christina D.

subjects: Digestibility

abstract: Ruminal fibre degradation is mediated by a complex community of rumen microbes, and its efficiency is crucial for optimal dairy productivity. Enzymes produced by rumen microbes are primarily responsible for degrading the complex structural polysaccharides that comprise fibre in the plant cell walls of feed materials. Because rumen microbes have evolved with their ruminant hosts over millions of years to perform this task, their enzymes are hypothesised to be optimally suited for activity at the temperature, pH range, and anaerobic environment of the rumen. However, fibre-rich diets are not fully digested, which represents a loss in potential animal productivity. Thus, there is opportunity to improve fibre utilisation through treating feeds with rumen microbe-derived fibrolytic enzymes and associated activities that enhance fibre degradation. This research aims to gain a better understanding of the key rumen microbes involved in fibre degradation and the mechanisms they employ to degrade fibre, by applying cultivation-based and culture-independent genomics approaches to rumen microbial communities of New Zealand dairy cattle. Using this knowledge, we aim to identify new opportunities for improving fibre degradation to enhance dairy productivity.
Rumen content samples were taken over the course of a year from a Waikato dairy production herd. Over 1,000 rumen bacterial cultures were obtained from the plant-adherent fraction of the rumen contents. Among these cultures, two, 59 and 103 potentially new families, genera and species of rumen bacteria were identified, respectively. Many of the novel strains are being genome sequenced within the Hungate 1000 rumen microbial reference genome programme, which is providing deeper insights into the range of mechanisms used by the individual strains for fibre degradation. This information has been used to guide the selection of rumen bacterial strains with considerable potential as fibrolytic enzyme producers in vitro, with the intent of developing the strains so that their enzymes may be used as feed pre-treatments for use on farm. Culture-independent metagenomic approaches were also used to explore the activities involved in fibre degradation from the rumen microbial communities. Functional screening has revealed a range of novel enzymes and a novel fibre disrupting activity. Enrichment for the cell-secreted proteins from the community revealed evidence of a diverse range of cellulosomes, which are cell-surface associated multi-enzyme complexes that efficiently degrade plant cell wall polysaccharides. Biochemical and structural characterisation of these proteins has been conducted.
In conclusion, cultivation and culture-independent genomic approaches have been applied to New Zealand bovine rumen microbial communities, and have provided considerable new insights into ruminal fibre degradation processes. Novel activities and bacterial species that display desirable activities on fibrous substrates in vitro are now being explored for their potential to improve ruminal fibre degradation, to allow the development of new technologies that will enhance dairy productivity.

text: Exploring rumen microbe-derived fibre-degrading activities for improving feed digestibility Ruminal fibre degradation is mediated by a complex community of rumen microbes, and its efficiency is crucial for optimal dairy productivity. Enzymes produced by rumen microbes are primarily responsible for degrading the complex structural polysaccharides that comprise fibre in the plant cell walls of feed materials. Because rumen microbes have evolved with their ruminant hosts over millions of years to perform this task, their enzymes are hypothesised to be optimally suited for activity at the temperature, pH range, and anaerobic environment of the rumen. However, fibre-rich diets are not fully digested, which represents a loss in potential animal productivity. Thus, there is opportunity to improve fibre utilisation through treating feeds with rumen microbe-derived fibrolytic enzymes and associated activities that enhance fibre degradation. This research aims to gain a better understanding of the key rumen microbes involved in fibre degradation and the mechanisms they employ to degrade fibre, by applying cultivation-based and culture-independent genomics approaches to rumen microbial communities of New Zealand dairy cattle. Using this knowledge, we aim to identify new opportunities for improving fibre degradation to enhance dairy productivity.
Rumen content samples were taken over the course of a year from a Waikato dairy production herd. Over 1,000 rumen bacterial cultures were obtained from the plant-adherent fraction of the rumen contents. Among these cultures, two, 59 and 103 potentially new families, genera and species of rumen bacteria were identified, respectively. Many of the novel strains are being genome sequenced within the Hungate 1000 rumen microbial reference genome programme, which is providing deeper insights into the range of mechanisms used by the individual strains for fibre degradation. This information has been used to guide the selection of rumen bacterial strains with considerable potential as fibrolytic enzyme producers in vitro, with the intent of developing the strains so that their enzymes may be used as feed pre-treatments for use on farm. Culture-independent metagenomic approaches were also used to explore the activities involved in fibre degradation from the rumen microbial communities. Functional screening has revealed a range of novel enzymes and a novel fibre disrupting activity. Enrichment for the cell-secreted proteins from the community revealed evidence of a diverse range of cellulosomes, which are cell-surface associated multi-enzyme complexes that efficiently degrade plant cell wall polysaccharides. Biochemical and structural characterisation of these proteins has been conducted.
In conclusion, cultivation and culture-independent genomic approaches have been applied to New Zealand bovine rumen microbial communities, and have provided considerable new insights into ruminal fibre degradation processes. Novel activities and bacterial species that display desirable activities on fibrous substrates in vitro are now being explored for their potential to improve ruminal fibre degradation, to allow the development of new technologies that will enhance dairy productivity.

year: 2014

title: New radiocarbon dates from the Bapot-1 site in Saipan and Neolithic dispersal by stratified diffusion

authors: Clark, Geoffrey

subjects: colonisation

abstract: The colonisation of the Mariana Islands in Western Micronesia is likely to represent an early ocean dispersal of more than 2000 km. Establishing the date of human arrival in the archipelago is important for modelling Neolithic expansion in Island Southeast Asia and the Pacific, particularly the role of long-distance dispersals. This paper presents new ¹⁴C results and a ΔR estimate from the Bapot-1 site on Saipan Island, which indicate human arrival at ca. 3400-3200 cal. BP. Archaeological chronologies of long-distance dispersal to Western Micronesia and the Lapita expansion (Bismarcks to Samoa) show that the Neolithic dispersal rate was increasing during the period ca. 3400-2900 cal. BP. The range-versus-time relationship is similar to stratified diffusion whereby a period of relatively slow expansion is succeeded by long-distance movement. An increase in new colonies created by long-distance migrants results in accelerating range expansion.

text: New radiocarbon dates from the Bapot-1 site in Saipan and Neolithic dispersal by stratified diffusion The colonisation of the Mariana Islands in Western Micronesia is likely to represent an early ocean dispersal of more than 2000 km. Establishing the date of human arrival in the archipelago is important for modelling Neolithic expansion in Island Southeast Asia and the Pacific, particularly the role of long-distance dispersals. This paper presents new ¹⁴C results and a ΔR estimate from the Bapot-1 site on Saipan Island, which indicate human arrival at ca. 3400-3200 cal. BP. Archaeological chronologies of long-distance dispersal to Western Micronesia and the Lapita expansion (Bismarcks to Samoa) show that the Neolithic dispersal rate was increasing during the period ca. 3400-2900 cal. BP. The range-versus-time relationship is similar to stratified diffusion whereby a period of relatively slow expansion is succeeded by long-distance movement. An increase in new colonies created by long-distance migrants results in accelerating range expansion.

year: 2010

title: Challenges to psychology in Aotearoa

authors: Awatere-Huata, Donna

subjects: Maori

abstract: Maori people are putting up with a lot right now. If governments can transfer $20 billion in the past ten years for hand outs and write offs to Pakeha people who have endured little, then they can do a lot better than the $150 million they’ve transferred to our people that have endured so much for 150 years.  The big issue is still the Treaty, and the need to re-negotiate this nation’s management. The challenge is to design a political system that is based on Maori ways of doing things rather than Pakeha ways of doing things. To achieve this requires relinquishing colonial patterns of thinking and the certainty that pakeha people and their ways are superior to Maori. For psychologists the issue is their role in maintaining Pakeha economic and political power. It may well be that psychologists provide lousy value for money from the Maori point of view, but provide excellent value for money from the government’s point of view.

text: Challenges to psychology in Aotearoa Maori people are putting up with a lot right now. If governments can transfer $20 billion in the past ten years for hand outs and write offs to Pakeha people who have endured little, then they can do a lot better than the $150 million they’ve transferred to our people that have endured so much for 150 years.  The big issue is still the Treaty, and the need to re-negotiate this nation’s management. The challenge is to design a political system that is based on Maori ways of doing things rather than Pakeha ways of doing things. To achieve this requires relinquishing colonial patterns of thinking and the certainty that pakeha people and their ways are superior to Maori. For psychologists the issue is their role in maintaining Pakeha economic and political power. It may well be that psychologists provide lousy value for money from the Maori point of view, but provide excellent value for money from the government’s point of view.

year: 1993