title: Two thermostable hemicellulases and their effects on wood pulps

authors: Bicho, Paul A.

abstract: Two hemicellulases, cloned from a thermophilic anaerobe (isolate TP8 6.3.3.1) were partially purified and characterised. The ability of these enzymes to hydrolyse the hemicellulose components of various types of pulps and their effects on the bleachability of radiata pine kraft pulp were examined. The xylanase (two preparations) and mannanase had broad pH optima (6-7.5). The xylanases had temperature optima of 70°C (10 min assay) and the mannanase had an optimum of 80°C (10 min assay). All the cloned enzymes were thermostable with more than 95% of the enzyme activity remaining after 24 hours at 70°C, in an unbuffered solution. Buffering affected the thermostability of the enzymes. The mannanase had a half life of 48 min at 85°C. The xylanases were able to hydrolyse xylans but also had a pH-dependent CM cellulase activity, but this was never more than 10% of the xylanase activity. The mannanase hydrolysed mannan, glucomannans and galactomannans. The glucose content of the glucomannans had little or no effect on mannanase activity but the galactose substituents of the galactomannans severely inhibited the hydrolysis of these substrates.

The thermostable xylanase hydrolysed more than 75% of soluble radiata pine xylan to low molecular weight (< DP10) xylo-oligomers. These included; xylose, xylobiose, xylotriose, arabinose-substituted xylobiose and xylotriose and 4-O-methyl glucuronic acid substituted xylotrioses. The arabinose substituents were bound to the terminal, non-reducing xylose residue; the glucuronic acid substituents may be bound to the non-reducing or central xylose residues of the substituted xylotriose. The thermostable mannanase also hydrolysed more than 75% of soluble radiata glucomannan, producing mannose, mannobiose, mannotriose, glucomannose and glucomannobiose.

The hemicellulases were used to treat (at 70°C, 24 hr) a variety of wood pulps, including kraft (softwood and hardwood), radiata NSAQ pulp, radiata CTMP and radiata TMP. Both enzymes solubilised their respective substrates from these pulps. The chemical pulps were more susceptible to enzymatic attack than the mechanical pulps, possibly due to the greater fibre porosity of the chemical pulps. The xylanase solubilised ~4% of the xylan and the mannanase solubilised 10% of the glucomannan from radiata kraft pulp. In comparison with other xylanases, the thermostable xylanase was less effective in solubilising xylan from kraft pulps. The hemicelluloses of kraft pulps that had been enzyme treated were extracted. The extracted xylan from the xylanase-treated pulp was lower in average DP than the xylan extracted from untreated pulps. The average DP of the extracted glucomannan from the mannanase-treated pulps was no different than that of glucomannans extracted from untreated pulps. The extracted xylan and glucomannan from untreated kraft pulps were readily hydrolysed by the xylanase and the mannanase respectively, suggesting that enzyme inaccessibility to the substrate within the fibre wall was the main cause of their resistance to enzymatic attack.

The effect of these enzymes on the bleachability of radiata kraft pulps was studied by measuring the reduction in kappa number (κ), relative to untreated controls, after a standard D/C E prebleaching sequence. The xylanase and the mannanase had little or no effect on the bleachability of radiata kraft pulps. Xylanase treated kraft pulp required a protease treatment after the hemicellulose treatment but before bleaching, in order to elicit any improvement in bleachability (~7% drop in κ relative to untreated control pulps). Mannanase treated kraft pulp showed no improvement in bleachability. For comparison commercial xylanases (including a thermostable xylanase) were used to treat radiata kraft pulps and did improve bleachability significantly. These enzymes also solubilised three to four times more xylan than the cloned, thermostable xylanase. Therefore, the ineffectiveness of the cloned xylanase may be due to its very limited ability to hydrolyse intra-fibril xylan in kraft pulp fibres.

text: Two thermostable hemicellulases and their effects on wood pulps Two hemicellulases, cloned from a thermophilic anaerobe (isolate TP8 6.3.3.1) were partially purified and characterised. The ability of these enzymes to hydrolyse the hemicellulose components of various types of pulps and their effects on the bleachability of radiata pine kraft pulp were examined. The xylanase (two preparations) and mannanase had broad pH optima (6-7.5). The xylanases had temperature optima of 70°C (10 min assay) and the mannanase had an optimum of 80°C (10 min assay). All the cloned enzymes were thermostable with more than 95% of the enzyme activity remaining after 24 hours at 70°C, in an unbuffered solution. Buffering affected the thermostability of the enzymes. The mannanase had a half life of 48 min at 85°C. The xylanases were able to hydrolyse xylans but also had a pH-dependent CM cellulase activity, but this was never more than 10% of the xylanase activity. The mannanase hydrolysed mannan, glucomannans and galactomannans. The glucose content of the glucomannans had little or no effect on mannanase activity but the galactose substituents of the galactomannans severely inhibited the hydrolysis of these substrates.

The thermostable xylanase hydrolysed more than 75% of soluble radiata pine xylan to low molecular weight (< DP10) xylo-oligomers. These included; xylose, xylobiose, xylotriose, arabinose-substituted xylobiose and xylotriose and 4-O-methyl glucuronic acid substituted xylotrioses. The arabinose substituents were bound to the terminal, non-reducing xylose residue; the glucuronic acid substituents may be bound to the non-reducing or central xylose residues of the substituted xylotriose. The thermostable mannanase also hydrolysed more than 75% of soluble radiata glucomannan, producing mannose, mannobiose, mannotriose, glucomannose and glucomannobiose.

The hemicellulases were used to treat (at 70°C, 24 hr) a variety of wood pulps, including kraft (softwood and hardwood), radiata NSAQ pulp, radiata CTMP and radiata TMP. Both enzymes solubilised their respective substrates from these pulps. The chemical pulps were more susceptible to enzymatic attack than the mechanical pulps, possibly due to the greater fibre porosity of the chemical pulps. The xylanase solubilised ~4% of the xylan and the mannanase solubilised 10% of the glucomannan from radiata kraft pulp. In comparison with other xylanases, the thermostable xylanase was less effective in solubilising xylan from kraft pulps. The hemicelluloses of kraft pulps that had been enzyme treated were extracted. The extracted xylan from the xylanase-treated pulp was lower in average DP than the xylan extracted from untreated pulps. The average DP of the extracted glucomannan from the mannanase-treated pulps was no different than that of glucomannans extracted from untreated pulps. The extracted xylan and glucomannan from untreated kraft pulps were readily hydrolysed by the xylanase and the mannanase respectively, suggesting that enzyme inaccessibility to the substrate within the fibre wall was the main cause of their resistance to enzymatic attack.

The effect of these enzymes on the bleachability of radiata kraft pulps was studied by measuring the reduction in kappa number (κ), relative to untreated controls, after a standard D/C E prebleaching sequence. The xylanase and the mannanase had little or no effect on the bleachability of radiata kraft pulps. Xylanase treated kraft pulp required a protease treatment after the hemicellulose treatment but before bleaching, in order to elicit any improvement in bleachability (~7% drop in κ relative to untreated control pulps). Mannanase treated kraft pulp showed no improvement in bleachability. For comparison commercial xylanases (including a thermostable xylanase) were used to treat radiata kraft pulps and did improve bleachability significantly. These enzymes also solubilised three to four times more xylan than the cloned, thermostable xylanase. Therefore, the ineffectiveness of the cloned xylanase may be due to its very limited ability to hydrolyse intra-fibril xylan in kraft pulp fibres.

year: 1992

title: Taking the road less travelled: Exploring the link between curiosity and resilience with 1NZSAS

authors: Bojilova, Alexandrina

subjects: Resilience

abstract: The pivotal question- ‘what goes right?’ in resilience must be explored further. We need to reconstruct resilience- beyond recovery or equanimity and towards capaci-ty for learning and thriving. This research unveils curiosity as a vital enabler for resilience. The relationship is studied in the context of resilience as a holistic, multifaceted and developable capability.
The primary aim of this research is to understand ‘what goes right’ for individuals who perform and thrive in ongoing change, ambiguity and significant risks, and to study the contextual conditions enabling their resilience. The overarching re-search question asks: “How is resilience built, sustained and developed to support capacity for thriving?” or put simply, “What goes right?”. The three supporting questions are “In what ways does curiosity serve as a resilience enabler? “What are the heuristics individuals employ to sustain and grow resilient mindsets?”, and “What are the contextual conditions that support access to resilience?”.
This research employs the principles of social constructivism as a methodological framework. It uses semi-structured interviews and narratives to capture detailed insights from 35 New Zealand Special Air Service (1NZSAS) members, for whom resilience is a critical value-in-action. 
The present research extends understanding of and applied ways to resilience, by reconstructing it through the prisms of curiosity. It frames and explores the heu-ristics individuals nurture and rely upon to thrive in and grow through challenges and setbacks. This research also outlines the contextual conditions that enable capacity for resilience in some of the most demanding conditions. The present research presents an integrated model of the findings, using curiosity and resili-ence as the axis that shape, drive and sustain capacity for thriving in ambiguity and change. Further to academic contribution, this thesis offers invaluable contri-butions to practitioners and leaders, as well as individuals willing to broaden and build greater access to resilience.

text: Taking the road less travelled: Exploring the link between curiosity and resilience with 1NZSAS The pivotal question- ‘what goes right?’ in resilience must be explored further. We need to reconstruct resilience- beyond recovery or equanimity and towards capaci-ty for learning and thriving. This research unveils curiosity as a vital enabler for resilience. The relationship is studied in the context of resilience as a holistic, multifaceted and developable capability.
The primary aim of this research is to understand ‘what goes right’ for individuals who perform and thrive in ongoing change, ambiguity and significant risks, and to study the contextual conditions enabling their resilience. The overarching re-search question asks: “How is resilience built, sustained and developed to support capacity for thriving?” or put simply, “What goes right?”. The three supporting questions are “In what ways does curiosity serve as a resilience enabler? “What are the heuristics individuals employ to sustain and grow resilient mindsets?”, and “What are the contextual conditions that support access to resilience?”.
This research employs the principles of social constructivism as a methodological framework. It uses semi-structured interviews and narratives to capture detailed insights from 35 New Zealand Special Air Service (1NZSAS) members, for whom resilience is a critical value-in-action. 
The present research extends understanding of and applied ways to resilience, by reconstructing it through the prisms of curiosity. It frames and explores the heu-ristics individuals nurture and rely upon to thrive in and grow through challenges and setbacks. This research also outlines the contextual conditions that enable capacity for resilience in some of the most demanding conditions. The present research presents an integrated model of the findings, using curiosity and resili-ence as the axis that shape, drive and sustain capacity for thriving in ambiguity and change. Further to academic contribution, this thesis offers invaluable contri-butions to practitioners and leaders, as well as individuals willing to broaden and build greater access to resilience.

year: 2021

title: The Rangatahi court

authors: Dickson, Matiu

abstract: It has become popular to use the marae setting as an alternative to the mainstream courts in dealing with young Māori offenders. The rationale is that taking young Māori offenders back to the marae to be dealt with in the youth justice system, encourages them to face up to their responsibilities and aids their rehabilitation back into the community. The expectation is that whānau will be present to support the young person and to help resolve his or her offending and bad behaviour. I supported this innovation when it was introduced but now I have second thoughts having seen that a marae that piloted this scheme was vandalised with graffiti painted on the marae buildings. In my view, when this happened the scheme to use marae should have ceased and an opportunity taken to rethink their use in this way. For a Māori the vandalism of their marae is like a physical assault on the person of their tupuna. This paper looks at the traditional role of marae in the Māori community and questions the use of marae as judicial settings. It suggests what needs to be done first to make this setting tika or appropriate.

text: The Rangatahi court It has become popular to use the marae setting as an alternative to the mainstream courts in dealing with young Māori offenders. The rationale is that taking young Māori offenders back to the marae to be dealt with in the youth justice system, encourages them to face up to their responsibilities and aids their rehabilitation back into the community. The expectation is that whānau will be present to support the young person and to help resolve his or her offending and bad behaviour. I supported this innovation when it was introduced but now I have second thoughts having seen that a marae that piloted this scheme was vandalised with graffiti painted on the marae buildings. In my view, when this happened the scheme to use marae should have ceased and an opportunity taken to rethink their use in this way. For a Māori the vandalism of their marae is like a physical assault on the person of their tupuna. This paper looks at the traditional role of marae in the Māori community and questions the use of marae as judicial settings. It suggests what needs to be done first to make this setting tika or appropriate.

year: 2011