Mating Genotype Analysis of Ganoderma lucidum Populations

[Objective] The mating genotype was studied and compared with esterase isozyme of Ganoderma lucidum populations between groups in order to clarify their differences in genetic relationship analysis. [Method] OWE-SOJ technique was applied to identify standard mating types and determinate mating genotype between groups of monokaryons isolates from 24 G. lucidum stains. Genetic relationships were analyzed by combined group mating genotype determination with esterase isozyme assay. [Result] All strains of G. lucidum could be divided into 7 large groups of the mating genotype. Four alleles of A factor, four alleles of B factor and one mixed alleles of A factor were found in this study. Distorted segregation ratio among monokaryon mycelia of G. lucidum had been observed in four kinds of mat- ing types to some extent. Twenty-eight different types of enzyme bands were determined in esterase isozyme test, Twenty-four strains of G. lucidum could be divided into 9 large groups through the cluster analysis when the genetic similarity coefficient was 0.73214. Comparing the results of mating genotype analysis and esterase isozyme analysis, it showed great similarity. [Conclusion] Mating genotype analysis could be used as an important supplementary method for strain identification and genetic diversity research.

Diversity surveys of soil bacterial community by cultivation-based methods and molecular fingerprinting techniques

By combining the cultivation methods with molecular fingerprinting techniques, the diversity surveys of soil bacterial community in 13 areas of China were carried out. The cultivable heterotrophic diversity was investigated by colony morphology on solid LB medium. Genetic diversity was measured as bands on denaturing gradient gel electrophoresis(DGGE) by the extraction and purification of the total soil DNA, and amplification of bacterial 16S rDNA fragments by polymerase chain reaction(PCR). The Shannon-Wiener indices of diversity(H), richness(S) and evenness(E H) were employed to estimate the diversity of soil bacterial community. The results showed that there was an obvious diversification existed in soil from the different areas. However, the genetic diversity estimated by PCR-DGGE can provide more comprehensive information on bacterial community than the cultivation-based methods. Therefore, it is suggested to combine the traditional methods with genetic fingerprinting techniques to survey and estimate soil bacterial diversity.

Mycelial Growth of Pleurotus Spp in Se-Enriched Culture Media

Selenium (Se) is an essential element to human. However, this element can be in low content in soil of some regions. Se deficiency may cause Keshan disease, thyroid dysfunction and osteoarthritis. The Se-enriched cereals are an interesting way to prevent these diseases. But, recent studies have shown that Se-enriched mushrooms are a better Se source. This occurs due to the high capacity of the fungi to absorb and transform the inorganic Se to organic forms, which are more bioavailable. Pleurotus ostreatus and Pleurotus eryngii are mushrooms species worldwide consumed and able to Se bioaccumulate. However, depending on the level of this element, it can be toxic for the fungus. Here we showed that the presence of the Se in culture medium decreases fungal growth rate, hyphae diameter and septum distance and causes alteration in color of colony. A garlic strong smell was directly proportional to Se level. P. eryngii was more tolerant to Se than P. ostreatus. So, it is important to screen this element level for Se-enriched mushroom production.