• The Korean Journal of Mycology
• /
• v.15 no.4
• /
• pp.254-259
• /
• 1987

This study was carried out to investigate the germination of four fungi under non-leaching and leaching incubation. The range of germination rates of Fusarium solani f. sp. pisi, Fusarium oxysporum f. sp. cucumerium, Mortierella, and Helminthosporium sativa incubated on sand saturated with various solutions without leaching were 90-99%, 31-45%, 38-62% and 86-98% respectively. The range of germination rates of Fusarium solani f. sp. pisi, Fusarium oxysporum f. sp. cucumerium, Mortierella n. sp and Helminthosporum sativa incubated on sand undergoing leaching were 51-63%, 13-25%, 15-37% and 47-80%, respectively. The germination rates of the four fungi tested were suppressed under leaching incubation.

• Journal of Microbiology and Biotechnology
• /
• v.18 no.4
• /
• pp.759-766
• /
• 2008

Among more than a hundred colonies of fungi isolated from soil samples, DY-52 has been screened as an extracellular chitin deacetylase (CDA) producer. The isolate was further identified as Mortierella sp., based on the morphological properties and the nucleotide sequence of its 18S rRNA gene. The fungus exhibited maximal growth in yeast peptone glucose (YPD) liquid medium containing 2% of glucose at pH 5.0 and $28^{\circ}C$ with 150 rpm. The CDA activity of DY-52 was maximal (20 U/mg) on the 3rd day of culture in the same medium. The CDA was inducible by addition of glucose and chitin. The enzyme contained two isoforms of molecular mass 50 kDa and 59 kDa. This enzyme showed a maximal activity at pH 5.5 and $60^{\circ}C$. In addition, it had a pH stability range of 4.5-8.0 and a temperature stability range of $4-40^{\circ}C$. The enzyme was enhanced in the presence of $Co^{2+}$ and $Ca^{2+}$. Among various substrates tested, WSCT-50 (water-soluble chitin, degree of deacetylation 50%), glycol chitin, and crab chitosan (DD 71-88%) were deacetylated. Moreover, the CDA can handle N-acetylglucosamine oligomers $(GlcNAc)_{2-7}$.

• The Korean Journal of Mycology
• /
• v.10 no.3
• /
• pp.119-124
• /
• 1982

The characteristics of the six different agricultural soil from Michigan were as follows. Colwood and Capac soil were loam, Gilford and Ceresco were sandy clay loam, Sission was clay loam, and Spinks was sandy loam. pH of Gilford sandy clay loam was 6.6 whereas that of the soil ranged $5.4{\sim}5.9$. Gilford sandy loam found to contain a relatively higher amount of organic matters as compared to other soils. Furthermore, the numbers of bacteria in Gilford sandy clay loam were significantly higher than those in other soils. The populations of fungi in Gilford sandy clay loam and Colwood loam soils were significantly greater than those in other soils. On the other hand, the densities of actinomycetes in Gilford sandy clay loam and Ceresco sandy clay loam soils were significantly different from those in other soils. The population of anaerobic bacteria varied depending on the soils; Ceresco sandy clay loam, Capac loam, Colwood loam soils have higher numbers of bacteria, whereas Gilford sandy clay loam was very lesser than the other soils. In the $^{14}C-glucose$ respiration by soil microorganisms after 10 hrs, the respiration rate was decreasing in the order of Ceresco sandy clay loam, Spinks sandy loam, Colwood loam, Sission clay loam, Capac loam and Gilford sandy clay loam. Germination of test propagules on natural soil soil was $0{\sim}5%$, and it was germinated $90{\sim}98%$ on autoclaved soil and PDA. The propagules differed in thier germination response to nutrients added to the soils. In general, more nutrients were required to promote germination on Capac loam and Gilford sandy loam soil than Spinks sandy loam soil. Especially Mortierella n. sp. required more nutrients for germination to obtain the same ratio as Helminthosporium victoriae.