Comparative chemical characterization of pigmented and less pigmented cell walls of Alternaria tenuissima.
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.
Kishore
Kankipati Hara
KH
Biology Division, Indian Institute of Chemical Technology, Hyderabad 500 007, India.
Kanjilal
Sanjit
S
Misra
Sunil
S
Reddy
Chinnathimma Rajagopal
CR
Murty
Upadyayula Suryanarayana
US
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
D000596:Amino Acids; D005227:Fatty Acids; D006601:Hexoses; D008543:Melanins; D010429:Pentoses; D010860:Pigments, Biological