Isolation of a Natural Polysaccharide from Two Dimorphic Fungi and Its Biological Activities

Arun Raj, T R (2009) Isolation of a Natural Polysaccharide from Two Dimorphic Fungi and Its Biological Activities. Masters thesis, College of Pharmacy, Sri Ramakrishna Institute of Paramedical Sciences, Coimbatore.


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The isolated fungal chitosan and commercial chitosan were tested for their anti bacterial activity against Gram positive and Gram negative organisms by disc diffusion method using Ciprofloxacin (5mg/disc) as standard. Gram Positive Organisms: Both Micrococcus luteus and Bacillus subtilis were found to be sensitive to all the isolated fungal chitosan and commercial chitosan. The chitosan did not show sensitivity against clinical isolate Staphylococcus aureus as well as the Staphylococcus aureus NCIM 5021 not sensive to chitosan isolated from M.rouxii. Gram Negative Organisms: Gram negative organisms such as E.coli, clinical isolate E.coli, P.vulgaris and K.pneumoniae, Pseudomonas aeruginosa and P.vulgaris was found to be highly sensitive to all the isolated fungal and commercial chitosan. Clinical isolate P.aeruginosa did not show any zone of inhibition against both isolated and commercial chitosan. The growth inhibitory effect of the isolated chitosan against bacteria is due to free-NH3 + groups, which are responsible for the binding of negative charges on the bacterial cell surface to bring about antibacterial activity (Chen C., et al., 1998). Our aim is to produce chitosan a natural polysaccharide, from a dimorphic fungus and we identified, that Mycotypha africana NCIM 1230, a dimorphic fungi is able to produce the polysaccharide and is compared with another dimorphic fungi Mucor rouxii MTCC 386 which was used as a reference. The chitosan produced using the above two species was comparable to the commercial chitosan and some of its characteristics were even superior to the commercial source like the present finding typically has at least 80-95% of deacetylation. This level of deacetylation provides high quality chitosan with consistent functional properties. In medium optimization the yield of chitin and chitosan content of fungi depends on the fungal strains, mycelial age, and composition of the growth medium. In our study the inclusion of glucose as a carbon source and peptone as a nitrogen source led to the highest yield of chitin and chitosan in Mucor rouxii MTCC 386 and the inclusion of maltose as a carbon source and corn steep liquor as a nitrogen source led to the highest yield of chitin and chitosan in Mycotypha africana NCIM1230. The present study clearly indicated that pH 5 is optimum for chitosan production by two dimorphic fungi such as M.rouxii MTCC386 and M.africana NCIM1230, due to the more activity of chitin deacetylase enzyme in that particular pH. The profile of both isolated and commercial chitosan showed similar FT-IR and NMR spectra. The comparison of the X-ray diffraction patterns of the fungal chitosan S1(Mycotypha africana), S2 (Mucor rouxii) and S3 (commercial chitosan) showed that less deacetylated the higher its crystallinity. The commercial chitosan is more crystalline than those from fungal biomass. The viscosity of the isolated fungal chitosan was in the range of 6-9 cP where as commercial chitosan having the viscosity of 123 cP (Table no.7) the results was correlated as described (Pochanavanich and Suntornsuk. 2002). The low ash content indicates that fungal chitosan are of with improved quality and clarity so, it can be used for medical and dietary purpose. The moisture content of the fungal chitosan from two dimorphic fungi and commercial chitosan are within the pharmaceutical grade specification i.e <10%. The DPPH free radical scavenging effect of isolated chitosan was more than that of standard compound, ascorbic acid.This shows a good free radical scavenging activity of the fungal chitosan. The isolated chitosan from both of the dimorphic fungi showed good antibacterial activity against Gram positive bacteria and Gram negative bacteria, including pathogenic organisms. Based on the results it may be concluded that any dimorphic fungi can be able to produce chitosan irrespective of the morphological form. Among the two dimorphic fungi M.rouxii MTCC 386 yields more chitosan than M.africana NCIM 1230 and could be the perfect alternative source for commercial chitosan. The less crystalline nature of the fungal chitosan indicated that it is deacetylated more and can be widely used for different applications. This work suggested that the chitosan production from dimorphic fungi can be further optimized and may be genetically modified in near future to improve the yield in a large scale production.

Item Type: Thesis (Masters)
Additional Information: Reg No.26073651
Uncontrolled Keywords: Isolation ; Natural Polysaccharide ; Two Dimorphic Fungi ; Biological Activities.
Subjects: PHARMACY > Pharmaceutical Biotechnology
Depositing User: Ravindran C
Date Deposited: 06 Feb 2018 10:54
Last Modified: 15 May 2018 23:34

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