title: Comparative chemical characterization of pigmented and less pigmented cell walls of Alternaria tenuissima.
abstract: Alternaria tenuissima, the parasitic fungus, was obtained from the pruned upper-cut surfaces of mulberry stems. This fungus contains dark pigment because of the presence of melanin in the cell wall. To obtain less-pigmented cell walls, this fungus was grown under dark condition. When the pigmented and less-pigmented cell walls were chemically analyzed, no differences were observed in amino-acid composition, hexoses, or pentoses. However, in pigmented cell walls, higher contents of melanin (2.6%) were found than in less-pigmented cell walls (0.3%). Interestingly, a significant difference was observed in the relative fatty-acid compositions between these two types of cell walls. Among the major fatty acids, there were increased concentrations of tetradecanoic acid (C14:0), hexadecanoic acid (C16:0), 9-hexadecenoic acid (C16: 1,Delta 9), and 9-octadecanoic acid (C18:1,Delta 9) and a concomitant decrease in 9,12-octadecadienoic acid (C18:2,Delta 9,12) in less-pigmented compared with pigmented cell walls. This difference in fatty-acid composition may be related to the higher percentage of melanin in the pigmented than the less-pigmented cell walls. Lesser amounts of 9,12-octadecadienoic acid in less-pigmented cell walls may have been caused by the growth of the fungus under environmental stress conditions. An interesting observation was the presence in pigmented cell walls only of methyl-substituted fatty acids with carbon numbers C14 to C17, but their occurrence could not be ascertained in the present study.
authors.affiliation: Biology Division, Indian Institute of Chemical Technology, Hyderabad 500 007, India.
authors.forename: Kankipati Hara
authors.initials: KH
authors.lastname: Kishore
authors.forename: Sanjit
authors.initials: S
authors.lastname: Kanjilal
authors.forename: Sunil
authors.initials: S
authors.lastname: Misra
authors.forename: Chinnathimma Rajagopal
authors.initials: CR
authors.lastname: Reddy
authors.forename: Upadyayula Suryanarayana
authors.initials: US
authors.lastname: Murty
mesh_terms: D000528:Alternaria / Q000737:chemistry* / Q000302:isolation & purification; D000596:Amino Acids / Q000032:analysis; D002473:Cell Wall / Q000737:chemistry*; D002855:Chromatography, Thin Layer; D003624:Darkness; D005227:Fatty Acids / Q000032:analysis; D006601:Hexoses / Q000032:analysis; D008543:Melanins / Q000032:analysis; D031625:Morus / Q000382:microbiology; D010429:Pentoses / Q000032:analysis; D010860:Pigments, Biological; D018547:Plant Stems / Q000382:microbiology
chemical_list: D000596:Amino Acids; D005227:Fatty Acids; D006601:Hexoses; D008543:Melanins; D010429:Pentoses; D010860:Pigments, Biological