Effect of demethylallosamidin, a chitinase inhibitor, on morphology of fungus Geotrichum candidum.

Abstract

Demethylallosamidin (DMA, Fig. 1) was isolated as an insect chitinase inhibitor from the mycelia of Streptomyces sp. which is a producer of allosamidin (6). This new compound was also found to inhibit the Saccharomyces chitinase and the inhibitory activity on this enzyme was 100 times stronger than that of allosamidin ( Fig. 1) (8, 9). The yeast cells cultured with DMA were reported to show a clustered form compared with the cells grown without DMA. This observation supports a speculation that chitinase plays a role in the final fission of the septum that leads to cell separation. It has been speculated that fungal chitinase plays an important role in the growth and differentiation of all chitin-containing fungi (4, 5) . This communication deals with biological activities of DMA against a fungus, Geotrichum candidum which is known to show varied morphological changes during cultivation (1,2).A fungus, G. candidum AJ14212 (IFO 4597) was used throughout this work. For slide culture, 2% agar powder (pH 6.1) (Junsei Chemical Co., Tokyo, Japan) was used. For shake culture, Bacto YM Broth (pH 7.0 with NaOH or HCl) (Difco Laboratories, Detroit, MI, U.S.A.) was used. DMA was added to the above media at the concentration of 0.1, 1, 10, and 100,ug/ml respectively.One milliliter of the spore suspension prepared ordinarily was put in each vial and the vials were stocked in a refrigerator at -80°C as a seed culture. For agar slide culture, spore suspension was streaked on a thin agar gel and the agar was covered with a cover glass and this was incubated at 25°C for 2-6 days. For liquid

Chitinases: An update

“…Lorito et al ., 1998,[63] reported the isolation of about 42 kDa endochitinase from Trichoderma . As reported by Yamanaka et al ., 1994,[64] Sandor et al ., 1998,[65] fungal cell wall chitinases have also been associated with their role in filamentous fungal sporulation since the chitinase inhibitors demethylallosamidin or allosamidin led to the inhibition of fragmentation of hyphae into arthroconidia. Trichoderma spp .…”

Novel Biological Activities of Allosamidins

“…Allosamidins have been used to investigate physiological roles in a variety of organisms, which are summarized in Table 1. Allosamidins inhibit insect moulting [7,32,33,34] and the cell separation of yeast [35,36], indicating that these enzymes play an essential role in degrading the old cuticle and during fission of the septum, respectively. In fungi, it has been postulated that chitinase is necessary for fungal growth such as hyphal growth and branching [37], but a critical effect of allosamidins in fungal growth has not been observed [38,39], though a weak fungistatic effect of allosamidin on autolyzing Penicillium mycelia has been reported [40].…”