aspergillus
TRANSCRIPT
a bioprospecting fungus for the production of
EXOPOLYSACCHARIDE
Speaker – Siddhanta MohantyGuided By – Dr. B. Mittra
DEPT. OF BIOSCIENCE AND BIOTECHNOLOGYFAKIR MOHAN UNIVERSITY
INTRODUCTION MATERIALS AND METHODS
◦ ISOLATION◦ SCREENING◦ CULTURE MEDIUM AND CULTIVATION◦ ISOLATION AND PURIFICATION
ANALYSIS OF POLYSACCHARIDES◦ CHROMATOGRAPHIC ANALYSIS◦ COLORIMETRIC ANALYSIS
RESULTS USES REFERENCES
Aspergillus niger is a fungus and one of the most common species of the genus Aspergillus.
It is ubiquitous in soil and commonly reported from indoor environments.
Exopolysaccharides are high-molecular-weight polymers that are composed of sugar residues and are secreted by a microorganism into the surrounding environment.
The fungal pathogen A. niger was isolated from soil.
It was cultured on sabourad agar medium and was incubated at 26- 27 degree Celsius of 6 – 8 days in the dark.
Pure cultures were maintained separately on slants of sabourad medium.
The fungus was subjected to screening for polysaccharide production.
1. Isolation
The fungus was inoculated into a large test tube containing 15 ml of the screening medium an initial pH 6. at 30 deg.cel.
Five days old cultures were heated at 80 deg.cel. for 15 min.
Two volumes of ethanol were added to the supernatant and the resulting precipitate was collected by centrifugation.
The precipitate was dissolved in water, used for quantitative estimation of the sugar.
The A. niger was grown in the 250 ml flask containing 100ml of the medium.
One medium was sucrose and the other contained maltose. The media were adjusted to different pH 5,7,9 with 1N. NaOH
and different fermentation periods of 10-15 days. Each cotton plugged flask was autoclaved at 120 deg.cel. For
15min. And then allowed cooling.
The cultivated fungal cell mass was collected on a fine cloth dried at 60 deg.cel. Overnight and weighed.
The culture broth was heated for 15min.at 60 deg. cel. and then cell free solution was obtained by centrifugation.
The crude polysaccharide was separated from the supernatant by the addition of two volumes of ethanol and the precipitate that wound around the stirrer.
The precipitation procedure was repeated thrice and the final product was dried at 60 deg. cel. And ground to a fine powder.
The sugars in the isolates were identified by ascending chromatography on whatmann No-1 filter paper. Using n-butanol as solvent.
The spots were developed by ammoniacal silver nitrate.
Sugars on chromatograms were visualized by spraying silver nitrate.
1. Chromatographic Analysis
Sugars react with the anthrone reagent under acidic conditions to yield a blue-green color.
The sample is mixed with sulfuric acid and the anthrone reagent and then boiled until the reaction is completed.
The solution is then allowed to cool and its absorbance is measured at 620 nm.
There is a linear relationship between the absorbance and the amount of sugar that was present in the original sample.
The polysaccharide can be detected by this process.
Two carbon sources sucrose and maltose were used to induce extracellular polysaccharide production in A. niger on 10 days and 15 days of incubation under three pH condition pH 5, pH 6, pH 9.
Max. 86.9 mg polysaccharide per 100 ml produce at pH 7.
The maximum production of polysaccharides and mycellial growth achieved in 15 days.
Exopolysaccharides used as a gelling agent, and for thickening drinks, ice cream and cosmetics.
It is used in various pharmaceutical preparations different types of medical products, including burn dressings.
Exopolysaccharides used in paper, paperboard, and card stock and of textiles made from cotton, linen, and other plant fibers.
These are used as inactive fillers in tablets and as thickeners and stabilizers in processed foods.
Suresh and Mody (2009). "Microbial Exopolysaccharides: Variety and Potential Applications". Microbial Production of Biopolymers and Polymer Precursors. Caister Academic Press. ISBN 978-1-904455-36-3.
Welman AD (2009). "Exploitation of Exopolysaccharides from lactic acid bacteria". Bacterial Polysaccharides: Current Innovations and Future Trends. Caister Academic Press. ISBN 978-1-904455-45-5.
Ljungh A, Wadstrom T (editors) (2009). Lactobacillus Molecular Biology: From Genomics to Probiotics. Caister Academic Press. ISBN 978-1-904455-41-7.
Ullrich M (editor) (2009). Bacterial Polysaccharides: Current Innovations and Future Trends. Caister Academic Press. ISBN 978-1-904455-45-5.
Samson RA, Houbraken J, Summerbell RC, Flannigan B, Miller JD (2001). Common and important species of fungi and actinomycetes in indoor environments. In: Microogranisms in Home and Indoor Work Environments. New York: Taylor & Francis. pp. 287–292. ISBN.
Abarca M, Bragulat M, Castellá G, Cabañes F (1994)."Ochratoxin A production by strains of Aspergillus niger var. niger". Appl Environ Microbiol 60 (7): 2650–2.PMID 8074536.
Schuster E, Dunn-Coleman N, Frisvad JC, Van Dijck PW (August 2002). "On the safety of Aspergillus niger--a review".Applied microbiology and biotechnology 59 (4-5): 426–35.doi:10.1007/s00253-002-1032-6. PMID 12172605.
