Qiu Liu

A developed DNA extraction method for different soil samples.

Four DNA extraction methods namely SDS‐hyperhaline method (I), modified SDS‐hyperhaline method (II), indirect method (III), alkaline lysis method (IV) were evaluated by comparing DNA yield, spectrophotometric quality, genomic integrity and PCR suitability in this paper. The results showed that high DNA yields were obtained by method I, II and IV. However, higher quality of DNA was gained by method III and IV. Based on the results of the Pulsed‐Field Gel Electrophoresis (PFGE), the completeness of DNA extracted by method IV was the best. About 6.0 μg DNA can be recovered from 1.0 g soil by method IV which involved to lysis cell by SDS and to precipitate impurities by adding potassium acetate and magnesium chloride Therefore, it is confirmed that method IV is a novel, reliable and versatile method for large‐scale DNA extraction involving less purification steps for various soil samples. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Diversity analysis of type I ketosynthase in rhizosphere soil of cucumber.

Fusarium wilt [Fusarium oxysporum (Sch1.) f.sp. cucumerinum Owen.] is a major soil‐borne disease of cucumber worldwide, and can cause huge yield losses. Biological control of Fusarium wilt of cucumber has received considerable attention. Many bacteria, particularly actinomycetes, are known to produce secondary metabolites synthesized by Polyketide synthases (PKSs) with a diverse range of biological activities.

Antifungal activity change of Streptomyces rimosus MY02 mediated by confront culture with other microorganism

Streptomyces rimosus can produce antibacterial and antifungal antibiotics, which have important applications in medicine and agriculture. Seventy‐nine microbial strains were employed to assay interaction between S. rimosus MY02 and different fungi, actinomyces, and bacteria when confront cultured on solid media. The results showed that the presence of a microorganism might affect the activity of another one. When S. rimosus MY02 confront cultured with other microorganisms, the inductive effect might be positive or negative. In this study, fungi showed to be effective elicitors, with a highest inductivity rate of 90.1%, and all of fungi showed positive induction behavior. Followed by bacteria with 59.6% of the tested bacterial strains showing positive inductivity, and the highest inductivity was 54.9%. Only six actinomyces (counting for 40% of the tested actinomyces strains) showed positive inductivity, and the highest induction rate of the strain NK413 was 34.1%. We also found that growth of most of bacteria or actinomyces which showed negative inductivity were similar or better than that of the strain MY02. However, the growth status of the strains was not positive related to inducing ability directly.

Effect of different enrichment strategies on microbial community structure in petroleum-contaminated marine sediment in Dalian, China

An oil spill occurred at Xingang Port, Dalian, China in 2010. Four years after this spill, oil contamination was still detected in samples collected nearby. In this study, the strains that evolved in the sediment were screened by high-throughput sequencing technology. Most of these strains were genera reported to have functions associated with crude oil biodegradation. The diversities and numbers of microbes were monitored through enrichment culturing; the dominant strains propagated at first, but the enrichment could not be continued, which indicated that the prolonged culture was not effective in the enrichment of the micro-consortium. Oxygen was also observed to affect the propagation of the dominant microbes. The results showed the role of culture strategies and oxygen in the enrichment of the petroleum-degrading microbes. Therefore, dominant strains could be screened by optimizing both the enrichment time and oxygen concentration used for culturing to facilitate oil biodegradation in the marine ecosystem.