An efficient marker-free genome editing method for Aspergillus niger / 生物工程学报

Aspergillus niger is an important industrial strain which has been widely used for production of enzymes and organic acids. Genome modification of A. niger is required to further improve its potential for industrial production. CRISPR/Cas9 is a widely used genome editing technique for A. niger, but its application in industrial strains modification is hampered by the need for integration of a selection marker into the genome or low gene editing efficiency. Here we report a highly efficient marker-free genome editing method for A. niger based on CRISPR/Cas9 technique. Firstly, we constructed a co-expression plasmid of sgRNA and Cas9 with a replication initiation region fragment AMA1 (autonomously maintained in Aspergillus) by using 5S rRNA promoter which improved sgRNA expression. Meanwhile, a strain deficient in non-homologous end-joining (NHEJ) was developed by knocking out the kusA gene. Finally, we took advantage of the instability of plasmid containing AMA1 fragment to cure the co-expression plasmid containing sgRNA and Cas9 through passaging on non-selective plate. With this method, the efficiency of gene editing reached 100% when using maker-free donor DNA with a short homologous arm of 20 bp. This method may facilitate investigation of gene functions and construction of cell factories for A. niger.

Application of WeChat quality control circle activity for improving health care workers' hand hygiene compliance / 中国感染控制杂志

Objective To carry out hand hygiene(HH) quality control circle(QCC) activity by using WeChat group, improve HH compliance of health care workers(HCWs), and enhance the circle members' ability to solve problems.Methods In June 2015, 11 healthcare-associated infection control professionals in a hospital created HH WeChat group by using cellphones, activity cycle was once every two weeks, professionals analyzed the existing problems, and formulated countermeasures as well as implemented methods by group chat form, circle members introduced and implemented strategies to HCWs in their departments, so as to achieve the implementation effect.Results After the creating of WeChat QCC, HCWs' HH compliance increased from 56.71% before activity to 85.94% after activity, difference was statistically significant (X2=61.928, P<0.05);QCC members' responsibility, self-confidence, enthusiasm, harmony degree, team cohesiveness, quality control technique, communication, coordination, and problem-solving skill were all significantly improved.Conclusion Application of WeChat QCC activity can improve HH compliance of HCWs and the ability of circle members.