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  • 1
    ISSN: 1432-072X
    Keywords: Ciliate culture ; Endosymbiosis ; Interspecies hydrogen transfer ; Hydrogenosome ; Methanogenic bacteria ; Methanoplanus endosymbiosus sp. nov. ; Metopus contortus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Epifluorescence microscopy revealed the presence of a methanogenic bacterium as an endosymbiont in the sapropelic marine ciliate Metopus contortus. The in situ methanogenic activity of the symbiont could be demonstrated. The isolated endosymbiont was an irregular, disc-shaped bacterium with a diameter of 1.6–3.4 μm. It had a generation time of 7 or 12 hours on growth on H2/CO2 or formate, respectively. The temperature range for growth was between 16 and 36°C with an optimum at 32°C. The optimal pH range for growth was 6.8 to 7.3. Salts, with an optimum concentration of 0.25 M, and tungsten were required for growth. The mol% G+C was 38.7%. The cell envelope consisted of proteins and a glycoprotein with an apparent molecular weight of 110,000. Morphology, antigenic relationship and the G+C content established the isolate MC1 as a new species of the genus Methanoplanus, and the name Methanoplanus endosymbiosus is proposed.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-072X
    Keywords: Anaerobic fungi ; Cellulase secretion ; Xylanase secretion ; Glucohydrolase ; Neocallimastix
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Four anaerobic fungi were grown on filter paper cellulose and monitored over a 7–8 days period for substrate utilisation, fermentation products, and secretion of cellulolytic and xylanolytic enzymes. Two of the fungi (N1 and N2) were Neocallimastix species isolated from a ruminant (sheep) and the other two fungi were Piromyces species (E2 and R1) isolated from an Indian Elephant and an Indian Rhinoceros, respectively. The tested anaerobic fungi degraded the filter paper cellulose almost completely and estimated cellulose digestion rates were 0.25, 0.13, 0.21 and 0.18 g · 1-1 · h-1 for strains E2, N1, N2, R1, respectively. All strains secreted cellulolytic and xylanolytic enzymes, including endoglucanase, exoglucanase, β-glucosidase and xylanase. Strain E2 secreted the highest levels of enzymes in a relatively short time. The product formation on avicel by enzymes secreted by the four fungi was studied. Both in the presence and absence of glucurono-1,5-δ-lactone, a specific inhibitor of β-glucosidase, mainly glucose was formed but no cellobiose. Therefore the exoglucanase secreted by the four fungi is probably a glucohydrolase.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-072X
    Keywords: Anaerobic fungi ; Methanogenic bacteria ; Coculture Neocallimastix ; Cellulase secretion ; Enzyme location
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Neocallimastix strain N1, an isolate from a ruminant (sheep), was cocultured with three Methanobacterium formicicum strains, Methanosarcina barkeri, and Methanobrevibacter smithii. The coculture with Methanobacterium formicicum strains resulted in the highest production of cellulolytic and xylanolytic enzymes. Subsequently four anaerobic fungi, two Neocallimastix strains (N1 and N2) from a ruminant and two Piromyces species from non-ruminants (E2 and R1), were grown in coculture with Methanobacterium formicicum DSM 3637 on filter paper cellulose and monitored over a 7-day period for substrate utilisation, fermentation products, and secretion of cellulolytic and xylanolytic enzymes. Methanogens caused a shift in fermentation products to more acetate and less ethanol, lactate and succinate. Furthermore the cellulose digestion rate increased by coculture. For cocultures of Neoallimastix strains with Methanobacterium formicicum strains the cellulolytic and xylanolytic enzyme production increased. Avicelase, CMCase and xylanase were almost completely secreted into the medium, while 40–60% of the β-glucosidase was found to be cell bound. Coculture had no significant effect on the location of cellulolytic and xylanolytic enzymes.
    Type of Medium: Electronic Resource
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