Journal of Microbiology and Biotechnology

1-7

Authors: Yong Zhao

Vibrio parahemolyticus is an important pathogen that leads to food illness associated seafood. Therefore, rapid and reliable methods to detect and quantify the total viable V. parahaemolyticus in seafood are needed. In this assay, a RNA-based real-time reverse-transcriptase PCR (RT-qPCR) without an enrichment step has been developed for detection and quantification of the total viable V. parahaemolyticus in shrimp. RNA standards with the target segments were synthesized in vitro with T7 RNA polymerase and subsequently converted to cDNA for establishing the standard curve to quantify V. parahaemolyticus. The reaction efficiency was 94.56%, and was in the acceptable range. Without pre-enrichment, the sensitivity of RT-qPCR on quantifying V. parahaemolyticus in shrimp was 58 cfu/g, approximately. In addition, the survival of V. parahaemolyticus in spiked shrimp samples was quantified by RT-qPCR, DNA-based qPCR and standard plate count method. The quantification results of RT-qPCR have shown a good statistical correlation (R2=0.96) when compared to the standard plate count method. However, the correlation coefficient between plate count method and DNA-based qPCR was only 0.85 for quantifying V. parahaemolyticus. Based on the results, this new method could be an effective way for providing reliable quantitative data on viable V. parahaemolyticus in shrimp.

1-6

Authors: Yi Zeng

The presence of HPV DNA in cases of esophageal squamous-cell carcinoma has been reported repeatedly from Tangshan area of China and other regions with a high incidence of esophageal carcinoma. In current study, to investigate the presence of human papillomavirus in esophageal squamous cell carcinoma, 112 formalin fixed paraffin-embedded tissue samples of ESCC from Tangshan were evaluated for HPV16/18E6, HPV16/18E7, P16 and P21 proteins by Immunohistochemistry method. 112 samples divided to two HPV PCR positive and negative groups of 83 and 29 cases respectively. From 83 slides of PCR positive group 73(87.95%), 48(57.83%), 75(90.36%) and 72(86.74%) of slides had positive reaction for HPV16/18 E6, HPV16/18E7, P21 and P16 respectively. From 29 PCR negative cases 14(48.27%) and 15(51.72%) showed positive staining reaction for P16 and P21 respectively. Results showed a good direct relation between expression of two common cancerous proteins, P16 and P21, and HPV specific proteins by higher positive slides of 72/83 (86.74%) for P16 and 75/83 (90.36%) for P21 in group of positive HPV PCR, in compare with the lower positive result in negative HPV PCR group of 15/29 (51.72%) and 14/29 (48.27%) for P16 and P21 respectively. In this study, P16 and P21 were implicated as two good markers with high expression in ESCC cancerous tissue with HPV infection probability. Findings in this study raise the possibility that HPV is involved in esophageal carcinogenesis. Further investigation with a large sample size over different areas may be warranted.

1-8

Authors: Shan-Jing Yao

Mycelial pellets are microbial particles formed during fungi culturing and their formation mechanisms are still under investigation. Spore aggregation is often considered as a crucial step for fungi to form mycelial pellets. In this work, the pellet formation processes of three fungi were investigated for proving the mycelial pellet formation without spores, and a marine-derived Aspergillus niger was selected as an example for the mechanism studies of mycelial pellet formation, and detailed processes of mycelium agglomeration and pellet formation were recorded. Experimental results showed that mycelial pellets can be formed directly from hyphae and the spore aggregation may not be an essential step. Moreover, the culture media pH had substantial effects on the pellet formation processes. Scanning electron microscope and infrared spectroscopy results indicated that the decrease of pelletization capacity was related to the change of extracellular polymeric substances. However, mycelium could not grow into mycelial pellets after adding 100 g/L talc into the culture media, while the spore inoculation method could still result in the formation of mycelial pellets under the same condition. This result indicated that although spore aggregation may not be essential, it is likely an enhancing factor for the mycelial pellet formation.