Thesis (MSc)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: The microbial degradation of the lignin carbohydrate complex of plant material is only
partially understood. Lignin carbohydrate complex was extracted from wheat straw and
subsequently analysed. An adjustment to the standard protocol was required to increase the
amount of lignin carbohydrate complex extracted from wheat straw. Characterization of the
lignin carbohydrate complex after trifluoacetic acid hydrolysis was done by capillary
electrophoresis. HPLC proved ineffective, as baseline separation could not be achieved.
Characterization of the lignin carbohydrate complex revealed that a large portion (68 %)
consisted of carbohydrate and lignin (20 %). Capillary electrophoresis of the trifluoroacetic
acid hydrolysates of the lignin carbohydrate complex revealed that the carbohydrates
consisted of mannose, xylose, arabinose, galactose, glucose and rhamnose. The major
monosaccharide present in the lignin carbohydrate complex was mannose which made up
34 % of the total carbohydrate composition. Ferulic and p-coumaric acid were present in the
lignin carbohydrate complex, but in concentrations less than 1 % of the lignin carbohydrate
complex. The lignin carbohydrate complex of wheat straw probably had a heterogenous
structure consisting of a variety of molecules, as molecular weight determination could not
be accurately determined. An estimated molecular weight of 5.9 kOa was determined. Ten
fungal strains (Aspergillus niger, Aureobasidium pul/u/ans, Bjerkandera adusta, Corio/us
versicolor, Lenzitus betu/ina, Phanerochaete chrysosporium, Pycnoporus coccineus,
Pycnoporus sanguineus 294, Pycnoporus sanguineus K5-2-3 and Trichoderma reeseï; were
evaluated for growth on the lignin carbohydrate complex. All strains except B. adusta
showed growth after 5 days with A. niger, A. pul/u/ans, C. versicolor, P. chrysosoporium and
T. reesei showing the best growth on the lignin carbohydrate complex. The culture fluid
revealed a number of proteins secreted by these organisms. The protein determination was
confirmed by SOS-PAGE which revealed an array of proteins ranging from 8 kOa to 180
kOA. Prominent bands between 26 kOa and 80 kOa could be observed in the culture fluid of A. niger, A. pul/ulans and T. reesei, but not in C. versicolor. Activity studies on the culture
fluid of these four strains revealed activity for xylanase, xylosidase, arabinofuranosidase,
ferulic acid esterase and laccase, with vast differences between the activities of the various
fungi. The enzymes of these fungal strains were also evaluated for their ability to degrade
xylan and sugar cane bagasse using capillary electrophoresis. It appeared that all the
organisms produced enzymes to degrade birchwood xylan. However, the electropherograms
revealed that the degradation patterns of birchwood xylan differed among these organisms
over the same time interval, as xylotetraose, xylotriose, xylobiose and xylose were released
in various concentrations. The electropherograms obtained from the enzyme hydrolysates of
sugar cane bagasse, pointed to the substrate being inaccessible. Electropherograms of the
culture fluid of A. niger, A. pul/ulans, C. versicolor and T. reesei, when incubated on the
lignin carbohydrate complex indicated similar peaks to those obtained and identified in the
trifluoroacetic acid hydrolysates. However, the electropherograms of the culture fluid of these
organisms revealed additional smaller peaks which could not be identified. The
electropherograms of the culture fluid of the various organisms also indicated a complete
release of some sugars, using the trifluoacetic acid hydrolysate of the lignin carbohydrate
complex as a control for the amount of sugars present. HPLC analyses revealed that after
72 h, no apparent degradation of the lignin carbohydrate complex took place as peak height
and areas appeared to be similar. These peaks could however not be identified due to a lack
of standards as well as baseline separation which could not be achieved. / AFRIKAANSE OPSOMMING: Tans word die mikrobiese afbraak van die lignienkoolhidraatkompleks van plant materiaal
slegs gedeeltelik verstaan. Lignienkoolhidraatkompleks was vanaf koringstrooi geïsoleer en
gevolglik geanaliseer. Daar moes van die standaard prosedure vir die ekstraksie van
lignienkoolhidraatkompleks afgewyk word ten einde beter lignienkoolhidraatkompleks
opbrengs te lewer. Karakterisering van die lignienkoolhidraatkompleks na
trifluoroasynsuurvertering was deur kapillêre elektroforese bepaal. Dit wou voorkom asof
kapillêre elektroforese "n beter opsie vir die analise van die verteerde monster van
lignienkoolhidraatkompleks is, vergeleke met hoëdruk vloeistof chromatografie. Daar was
gevind dat die lignienkoolhidraatkompleks uit 68 % koolhidraat en 20 % lignien bestaan.
Kapillêre elektroforese het die teenwoordigheid van die volgende suikers bevestig naamlik,
mannose, xilose, arabinose, glukose, galaktose en ramnose. Mannose was die
dominerende suiker in die lignienkoolhidraatkompleks wat 34 % van die totale koolhidraat
opbrengs uitgemaak het. Ferulien- en p-kumaarsuur kon ook identifiseer word, maar die
twee sure het minder as 1 % van die totale inhoud van die lignienkoolhidraatkompleks
uitgemaak. Vanuit resultate bekom wil dit voorkom dat die lignienkoolhidraatkompleks "n
heterogene molekuul is omdat die molekulêre gewig daarvan nie akkuraat bepaal kon word
nie. 'n Geskatte molekulêre grootte van ongeveer 5.9 kDa was bepaal met verwysing na die
hoogste piek wat in die chromatogram waargeneem was.
Tien fungus kulture was in die studie gebruik om hul vermoë te toets om op die lignienkoolhidraatkompleks
te groei, naamlik Aspergillus niger, Aureobasidium pullulans,
Bjerkandera adusfa, Goriolus versicolor, Lenziius betuline. Phanerochaefe chrysosporium,
Pycnoporus coccineus, Pycnoporus sanguineus 294, Pycnoporus sanguineus K5-2-3 en
Trichoderma reesei. B. eauste het nie groei na 5 dae getoon nie, en dit wou voorkom asof A.
niger, A. pul/ulans, G. versicolor, P. chrysosoporium en T. reesei die beste kon groei op die
substraat na 5 dae. Die kultuurvloeistof van die vier kulture het getoon dat proteïene deur hierdie organisms uitgeskei was. Hierdie proteinbepaling was ook bevestig deur SOS-PAGE,
wat bande tussen 8 kDa en 180 kDa gelewer het. Prominente bande tussen 26 kDa en 80
kDa kon waargeneem word in die kultuurvloeistof van A. niger, A. pul/ulans, en T. reesei,
maar nie in die kultuurvloeistof van C. versicolor nie. Aktiwiteitstudies op die kultuur
vloeistowwe het getoon dat daar aktiwiteit was vir die volgende ensieme, naamlik xilanase,
xilosidase, arabinofuranosidase en feruliensuur esterase. Hierdie aktiwiteit het aansienlik
verskil tussen die verskillende organismes.
Die ensieme van die vier organismes was ook gebruik om hul vermoë te toets om xilaan en
suikerriet af te breek. Daar was gevind dat xilaanafbraak verskillend was vir die organisms
oor dieselfde tydperk. Xilotetraose, xilotriose, xilobiose en xilose was in verskillende
konsentrasies gevind vir die verskillende organismes. Die elektroferogramme van die
kultuurvloeistof op suikerriet van die verskillende organismes het getoon dat die substraat
nie toeganklik vir die ensieme was nie. Die elektroferogramme van die kultuurvloeistof op
lignienkoolhidraatkompleks van die verskillende organismes het dieselfde pieke getoon soos
geïdentifiseer in die elektroferogramme van die trifluoroasynsuur vertering. Die
elektroferogramme met die ensiem vertering het egter addisionele pieke getoon wat nie
sigbaar op die elektroferogramme van die trifluoroasynsuur vertering was nie. Hierdie pieke
het min of meer dieselfde tyd ge-elueer as die monosakkariede. Kapillêre elektroforese het
ook getoon dat die ensiematiese afbraak van die lignienkoolhidraatkompleks gelei het tot
algehele vrystelling van sommige suikers, wanneer die trifluoroasynsuur vertering as
maatstaaf dien vir die hoeveelheid suikers teenwoordig in die lignienkoolhidraatkompleks.
Hoëdruk vloeistof chromatografie het getoon dat geen sigbare afbraak na 72 h van
inkubasie met die ensieme op die lignienkoolhidraatkompleks plaasgevind het nie aangesien
die piek hoogtes konstant gebly het. Hierdie pieke kon egter nie geïdentifiseer word nie as
gevolg van lae resolusie van die pieke asook standaarde wat nie beskikbaar was nie.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/53722 |
| Date | 03 1900 |
| Creators | Stevens, Gary Grant |
| Contributors | Prior, B. A., Van Zyl, W. H., Sandra, J. F., Stellenbosch University. Faculty of Science. Dept. of Microbiology. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | 106 p. : ill. |
| Rights | Stellenbosch University |
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