beta-Glucans are a kind of non-digestible carbohydrate (NDC) that are known for their benefits for human gut health, but there are very few studies on their fermentability by human colon microbiota. In this study four beta-glucans were selected for in vitro fermentation by three bifidobacteria. The beta-glucans included those from a seaweed called Laminaria digitata (laminarin), barley, a bacterium called Alcaligenes faecalis (curdlan), and a mushroom sclerotia from Pleurotus tuber-regium. Inulin from Dahlia tubers was used as control. / The content of beta-glucan in the NDCs prepared from the mushroom sclerotium of Pleurotus tuber-regium was 80.8 % with proteins less than 1.0 %, while that of curdlan, barley and laminarin all have more than 95% beta-glucan. All the beta -glucans contained almost purely glucose as their sugar components with only trace amount of mannose ( < 2%) being found in laminarin. beta-glucan from barley had a MW of 590 kDa and a linear chain with mixed 1→3 and 1→4 beta-linkages in the ratio of 1:3. Curdlan had a beta-(1→3) linked unbranched linear chain with a MW of 10 to 30 kDa. Laminarin had a beta-(1→3) linked backbone with beta-(1→6) branches, having a MW of 6 kDa. beta-Glucan from mushroom sclerotia had a highly branched main chain with mixed glycosidic 1→3, 1→4 and 1→6 beta-linkages with a MW of 96 kDa. / Batch systems of in vitro fermentation of individual NDCs by B.longum subsp. infantis ( B. infantis), B. longum and B. adolescentis were carried out for 24 h under anaerobic condition. All the systems showed a significant drop (p< 0.05) of at least 0.5 units in their pH values. The populations of B. infantis increased by 3 log10 CFU on all the NDCs while those of B. longum and B. adolescentis increased by about 1 to 1.5 log10 CFU and 2 to 2.3 log10 CFU, respectively. Utilization of the NDCs by the bifidobacteria evaluated by organic matter disappearance ranged from 4.52% in barley to 41.3% in inulin. The total short chain fatty acid (SCFA) produced by B. infantis was higher than that in B. longum and B. adolescentis for all the beta -glucans. The SCFA profile of inulin and all beta-glucans produced by all the bifidobacteria was dominated by acetate (96%). The ratio of acetic : propionic : butyric acid in the SCFA profile of the fermentation of all the beta-glucans by B. infantis was 8: 1: 1, which was very different from that of B. longum and B. adolescentis. / Based on the in vitro fermentation results, B. infantis was selected for a mechanistic study on the fermentation of the Pbeta-glucans from different sources by proteomic and molecular biology approaches. In the proteomic study, the gels of the two-dimensional difference gel electrophoresis (2D-DIGE) containing the total proteins from the B. infantis cells fermented with beta-glucans from barley, seaweed and mushroom sclerotia were compared with each other to isolate the differentially expressed protein spots. In all the comparisons, a total number of 198 protein spots were identified based on their mass spectra. These proteins were classified according to their functional annotation, including ABC transporters, phosphotransferase system (PTS), transketolase and others. Several genes encoding the proteins that probably play a role in the transport and degradation of beta-glucans including the ABC transporter gene, PTS gene and membrane protein gene underwent real time RT-PCR for transcriptional analysis. Hydrolytic enzyme activity assay showed that intracellular beta-1, 3 glucanase activity was present when B. infantis was incubated with beta-glucans from seaweed and mushroom. / Based on the above results, a model for beta-glucan catabolism in B. infantis was proposed. The fbeta -glucan molecules might be captured and imported inside the bacterial cells either by ABC transporters or PTS. They were then subjected to hydrolysis by glucan beta-1, 3 glucosidase. The released glucose molecules were readily incorporated into the central fermentation pathway, the 'bifid shunt', in which the hydrolyzed residues were further degraded or exported. This study has deepened our understanding on the fermentation of beta-glucans by bifidobacteria and demonstrated the potential of beta-glucans to be used as a novel prebiotic. / Zhao, Jinyang. / Source: Dissertation Abstracts International, Volume: 73-08, Section: B, page: . / Adviser: Peter Chi-Keung Cheung. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 147-162). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

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Wong Ka-kei. / Thesis submitted in: December 2004. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 123-139). / Abstracts in English and Chinese. / THESIS COMMITTEE --- p.i / ACKNOWNLEDGEMENT --- p.ii / ABSTRACT (ENGLISH VERSION) --- p.iii / ABSTRACT (CHINESE VERSION) --- p.v / LIST OF TABLES --- p.ix / ABBREVIATIONS --- p.xiii / Chapter CHAPTER 1 --- INTRODUCTION --- p.1 / Chapter 1.1 --- Edible mushrooms --- p.1 / Chapter 1.1.1 --- Classification and terminology --- p.1 / Chapter 1.1.2 --- Mode of nutrition --- p.3 / Chapter 1.1.3 --- World consumption --- p.3 / Chapter 1.1.4 --- Nutritional values of edible mushroom --- p.6 / Chapter 1.1.5 --- Medicinal values of mushrooms --- p.7 / Chapter 1.2 --- Mushroom mycelium --- p.11 / Chapter 1.2.1 --- Uses and applications --- p.11 / Chapter 1.2.2 --- Submerged fermentation (SmF) --- p.12 / Chapter 1.2.3 --- Factors affecting the growth of mycelium in submerged fermentation --- p.14 / Chapter 1.2.3.1 --- Nutritional requirements - Carbon sources --- p.14 / Chapter 1.2.3.2 --- Nutritional requirements ´ؤ Nitrogen sources --- p.16 / Chapter 1.2.3.3 --- Nutritional requirements ´ؤ Minerals --- p.16 / Chapter 1.2.3.4 --- Environmental factors ´ؤ Temperature --- p.17 / Chapter 1.2.3.5 --- Environmental factors - Aeration --- p.17 / Chapter 1.2.3.6 --- Environmental factors - Agitation --- p.18 / Chapter 1.2.4 --- Optimization of growth of mycelium and production of EPS --- p.18 / Chapter 1.3 --- Mushroom polysaccharides --- p.21 / Chapter 1.3.1 --- Biologically active mushroom polysaccharides --- p.21 / Chapter 1.3.2 --- Chemical structures of mushroom polysaccharides --- p.21 / Chapter 1.3.2.1 --- β-glucans --- p.23 / Chapter 1.3.2.2 --- α-glucans --- p.25 / Chapter 1.3.2.3 --- Mannans --- p.26 / Chapter 1.3.2.4 --- Protein-bound polysaccharides --- p.26 / Chapter 1.3.2.5 --- Other heteroglycans --- p.28 / Chapter 1.4 --- Mushrooms under investigation --- p.28 / Chapter 1.4.1 --- Pleurotus tuber-regium (Fr.) Sing. (PTR) --- p.28 / Chapter 1.4.2 --- Agrocybe cylindracea (AC) --- p.30 / Chapter 1.4.3 --- Grifola frondosa (GF) --- p.31 / Chapter 1.5 --- Objectives and experimental design --- p.32 / Chapter CHAPTER 2 --- MATERIALS AND METHODS --- p.35 / Chapter 2.1 --- Source of mushroom mycelium --- p.35 / Chapter 2.2 --- Effect of different carbon sources on submerged fermentation --- p.37 / Chapter 2.2.1 --- Production of mycelium by submerged fermentation using 250 mL and 1L shake-flasks --- p.37 / Chapter 2.2.2 --- Scale-up production of mycelium of PTR using fermentor --- p.39 / Chapter 2.2.3 --- Concentration of dissolved oxygen in 250 mL and 1L shake-flasks. --- p.39 / Chapter 2.3 --- Isolation and fractionation of mushroom polysaccharides --- p.40 / Chapter 2.3.1 --- Isolation of exo-polysaccharides (EPS) from culture medium by ethanol precipitation --- p.40 / Chapter 2.3.2 --- Isolation of EPS from culture medium by ultra-filtration --- p.40 / Chapter 2.3.3 --- Hot water extraction of PTR mycelium --- p.41 / Chapter 2.3.4 --- Fractionation of HWE by fractional ethanol precipitation --- p.41 / Chapter 2.4 --- Chemical composition of HWE and EPS --- p.42 / Chapter 2.4.1 --- Phenol-sulphuric acid method --- p.42 / Chapter 2.4.2 --- Modified Lowry method --- p.43 / Chapter 2.4.3 --- Monosaccharide composition analysis of HWE and EPS --- p.43 / Chapter 2.4.3.1 --- Acid depolymerization --- p.43 / Chapter 2.4.3.2 --- Neutral sugar derivatization --- p.44 / Chapter 2.4.3.3 --- Determination of neutral sugar composition by gas chromatography (GC) --- p.45 / Chapter 2.4.3.4 --- Uronic acid content --- p.46 / Chapter 2.5 --- Structural studies of HWE and EPS --- p.47 / Chapter 2.5.1 --- High Pressure Liquid Chromatography (HPLC) --- p.47 / Chapter 2.5.2 --- Methylation study and gas chromatography- mass spectrometry (GC-MS) --- p.48 / Chapter 2.5.2.1 --- Preparation of dry dimethyl sulfoxide (DMSO) --- p.48 / Chapter 2.5.2.2 --- Preparation of methylsulfinyl methyl sodium (CH3SOCH2-Na+) --- p.48 / Chapter 2.5.2.3 --- Methylation --- p.49 / Chapter 2.5.2.4 --- Extraction of methylated polysaccharide --- p.49 / Chapter 2.5.2.5 --- Acid depolymerization and preparation of aditol acetate derivatives --- p.50 / Chapter 2.5.2.6 --- Determination of partially methylated alditol acetates (PMAAs) by gas chromatography-mass spectrometry (GC-MS) --- p.50 / Chapter CHAPTER 3 --- RESULTS AND DISCUSSION --- p.51 / Chapter 3.1 --- "Production of mycelium and EPS of PTR, AC and GF by submerged fermentation in 250 mL shake-flask with liquid medium containing different carbon sources" --- p.51 / Chapter 3.1.1 --- "Mycelial biomass production of PTR, AC and GF" --- p.51 / Chapter 3.1.2 --- "Production of EPS of PTR, AC and GF" --- p.57 / Chapter 3.1.3 --- "Characterization of EPS of PTR, AC and GF" --- p.62 / Chapter 3.1.3.1 --- Carbohydrate and protein content --- p.62 / Chapter 3.1.3.2 --- Monosaccharide composition --- p.67 / Chapter 3.1.4 --- Summary --- p.72 / Chapter 3.2 --- "Production of mycelium, EPS of PTR by submerged fermentation in 1L shake-flask and 8L fermentor with liquid medium containing different carbon sources" --- p.75 / Chapter 3.2.1 --- Mycelial production of PTR --- p.75 / Chapter 3.2.2 --- EPS Production of PTR --- p.80 / Chapter 3.2.3 --- Chemical characteristics of EPS of PTR --- p.83 / Chapter 3.2.3.1 --- Carbohydrate and protein content --- p.83 / Chapter 3.2.3.2 --- Monosaccharide composition --- p.85 / Chapter 3.2.4 --- Structural characteristics of EPS of PTR --- p.87 / Chapter 3.2.4.1 --- Molecular weight of EPS of PTR by HPLC --- p.87 / Chapter 3.2.4.2 --- Glycosyl linkages of EPS of PTR by GC-MS of PMAA --- p.90 / Chapter 3.2.5 --- Summary --- p.93 / Chapter 3.3 --- Hot water extraction of mycelium of PTR from the scale-up submerged fermentation in 1L shake-flask and 8L fermentor with liquid medium containing different carbon sources --- p.95 / Chapter 3.3.1 --- Yield of hot water extract (HWE) of mycelium of PTR --- p.95 / Chapter 3.3.2 --- Chemical characteristics of HWE of PTR --- p.101 / Chapter 3.3.2.1 --- Carbohydrate and protein content --- p.101 / Chapter 3.3.2.2 --- Monosaccharide composition --- p.104 / Chapter 3.3.3 --- Structural characteristics of HWE of PTR --- p.112 / Chapter 3.3.3.1 --- Molecular weight of HWE of PTR by HPLC --- p.112 / Chapter 3.3.3.2 --- Glycosyl linkages of HWE of PTR by GC-MS ofPMAA --- p.116 / Chapter 3.3.4 --- Summary --- p.119 / Chapter CHAPTER 4 --- CONCLUSIONS AND FUTURE WORKS --- p.120 / Chapter 4.1 --- Conclusions --- p.120 / Chapter 4.2 --- Future works --- p.121 / REFERENCES --- p.123

Orientador: José Roberto Ernandes / Banca: Rubens Monti / Banca: João Atílio Jorge / Resumo: Para o aprimoramento do processo industrial de produção de bioetanol, é fundamental o conhecimento da bioquímica e fisiologia dos microrganismos envolvidos. Assim, este estudo tem o objetivo de obter informações bioquímicas de leveduras industriais, principalmente ao que se refere à hidrólise da sacarose e maltose pela enzima invertase (β-frutofuranosidase, EC 3.2.1.26) e maltase (α- glicosidase, EC 3.2.1.20) respectivamente. As linhagens industriais Ethanol RedTM (Fermentis/Lasaffre - linhagem francesa) PE-2, SA-1, CAT-1 e BG (linhagens brasileiras) foram cultivadas em meios contendo diferentes fontes de carbono (sacarose, glicose, frutose, maltose e galactose), suplementados com peptona e extrato de levedo, e avaliadas com relação a produção de biomassa, consumo da fonte de carbono, viabilidade celular e níveis de atividade invertásica e maltásica. Resultados mostraram que todas as linhagens apresentam crescimento rápido e intenso em sacarose, glicose e frutose, porém apresentam comportamento diferente em meios contendo maltose e galactose. Todas as linhagens crescem lentamente em galactose. Ethanol RedTM é mais adaptada para o crescimento em maltose do que as linhagens brasileiras PE-2 e SA-1. As outras linhagens brasileiras (CAT-1 e BG) não crescem em maltose devido à ausência de atividade maltásica. Com relação aos níveis de atividade invertásica, foi identificada a presença de três categorias de linhagens: uma com altos níveis de atividade (Ethanol RedTM), outra com níveis mais baixos (PE-2, CAT-1), e uma terceira categoria com atividade intermediária entre estas duas primeiras categorias (SA-1 e BG). Além do valor acadêmico, os resultados obtidos têm importância aplicada na medida em que indicam que as linhagens industriais produtoras de etanol combustível apresentam diferentes características fisiológicas, que podem ser exploradas para aperfeiçoar o processo de fermentação alcoólica / Abstract: For the improvement of the industrial ethanol fuel-producing process, it is crucial to understand the biochemistry and physiology of the microorganisms involved. This study aims to obtain biochemical information of industrial yeasts, especially when it refers to the hydrolysis of sucrose and maltose by the enzyme invertase (β-frutofuranosidase, EC 3.2.1.26) and maltase (α-glicosidase, EC 3.2.1.20) respectively. The industrial strains Ethanol RedTM (Fermentis/Lasaffre - French strain) PE-2, SA-1, CAT-1 and BG (Brazilian strains) were cultured in media containing different carbon sources (sucrose, glucose, fructose, maltose and galactose) supplemented with peptone and yeast extract, and evaluated relative to biomass production, carbon source consumption, cell viability and levels of invertase and maltase activities. Results showed that all strains exhibit rapid and intense growth in presence of sucrose, glucose and fructose, but they have differing behavior in media containing maltose and galactose. All strains grow slowly on galactose. Ethanol RedTM is more adapted for growing in maltose than Brazilian PE-2 and CAT- 1. The remaining Brazilian strains (BG and CAT-1) do not grow in maltose, due to the absence of maltase activity. As far as the levels of invertase activity is concerned, three categories of strains have been identified: with high activity levels (Ethanol RedTM), with lower levels (PE-2, CAT-1), and a third category with intermediate activity levels between these first two categories (SA-1 and BG). Besides academic value, the results obtained have applied significance in indicating that industrial ethanol fuel-producing strains exhibit different physiological characteristics that can be exploited to improve the fermentation process / Mestre

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Includes two of author's articles in pocket inside back cover. Includes bibliographical references (leaves 133-150) Diversity in the ruminal Gram negative bacterial species Selenomonas ruminantium has been investigated by DNA fingerprinting, DNA homology and plasmid profile analysis. Twenty different isolates from the sheep rumen were classified morphologically and by carbon source utilization.

Includes two of author's articles in pocket inside back cover. / Includes bibliographical references (leaves 133-150) / xii, 150 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Diversity in the ruminal Gram negative bacterial species Selenomonas ruminantium has been investigated by DNA fingerprinting, DNA homology and plasmid profile analysis. Twenty different isolates from the sheep rumen were classified morphologically and by carbon source utilization. / Thesis (Ph.D.)--University of Adelaide, Dept. of Animal Science, Waite Agricultural Research Institute, 1993

Erratum pages attached to back page. / Bibliography : leaves 125-147. / 147, [41] leaves : ill. (chiefly col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This study was undertaken to derive a strategy to reduce the potential of S. cerevisiae to produce hydrogen sulfide under oenologial conditions by altering the levels of active sulfite reductase in the cell. / Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Science, 2000