Direct production of polyhydroxybutyrate and alginate from crude glycerol by Azotobacter vinelandii using atmospheric nitrogen.

While biodiesel is drawing attention as an eco-friendly fuel, the use of crude glycerol, a byproduct of the fuel production process, has increasingly become a concern to be addressed. Here we show the development of a low-cost fermentation technology using an atmospheric nitrogen-fixing bacterium to recycle crude glycerol into functional biopolymers. Azotobacter vinelandii showed substantial growth on tap water-diluted crude glycerol without any pretreatment. The number of viable A. vinelandii cells increased over 1000-fold under optimal growth conditions. Most of the glycerol content (~ 0.2%) in the crude glycerol medium was completely depleted within 48 h of culture. Useful polymers, such as polyhydroxybutyrate and alginate, were also produced. Polyhydroxybutyrate productivity was increased ten-fold by blocking the alginate synthesis pathway. Although there are few examples of using crude glycerol directly as a carbon source for microbial fermentation, there are no reports on the use of crude glycerol without the addition of a nitrogen source. This study demonstrated that it is possible to develop a technology to produce industrially useful polymers from crude glycerol through energy-saving and energy-efficient fermentation using the atmospheric nitrogen-fixing microorganism A. vinelandii.

Effect of TT virus co-infection on interferon response in chronic hepatitis C patients.

AIM: TT virus (TTV) is a single stranded DNA virus found in serum of patients with post-transfusion non-A to -G hepatitis. TTV-DNA has been investigated in sera of patients with various liver diseases. This study aimed at finding whether co-infection with TTV in HCV patients, may influence the effect of interferon (IFN) in complete elimination of HCV, and analysed the correlation between HCV and TTV by semi-quantification of both HCV RNAs and TTV DNA. METHODS: In 28 chronic hepatitis C (CH-C) patients with TTV co-infection, the presence of TTV DNA was checked in sera six months before and after the end of IFN therapy. RESULT: Five out of 28 patients became negative for both HCV-RNA and TTV-DNA following IFN therapy. But 10 out of 28 patients persistently remained positive for both. Among the remaining 13 patients, 5 tested negative for HCV-RNA but positive for TTV-DNA. Post IFN therapy changes in serum alanine aminotransferase (ALT) levels did not appear to be influenced by the presence of TTV co-infection. HCV-RNA was found to be the most important predictor of IFN response in CH-C patients with TTV co-infection. TTV DNA level in sera had no correlation with IFN response. In addition, there was no relationship between HCV RNA and TTV DNA. CONCLUSION: Based on these results, it can be concluded that the effectiveness of IFN in eliminating HCV does not seem to be influenced by co-infection.