Zhang Hongxun

Determination of microbial diversity in Daqu, a fermentation starter culture of Maotai liquor, using nested PCR-denaturing gradient gel electrophoresis

This study endeavored to investigate the diversity of microbes present during the shaping, ripening and drying of Daqu, a fermentation starter culture and substrata complex of Maotai alcoholic spirit. A nested PCR-denaturing gradient gel electrophoresis technique was utilized with different combinations of primers. The results showed the presence of bacteria, yeasts and molds. The microflora, which originate from wheat, were readily detectable during every stage of the fermentation process. However, the microbial structure had clear differences in the shaping, ripening and drying processes. In the shaping stage, there was a high level of diversity of the LAB (lactic acid bacteria) and fungi in the shaped samples. In the ripening stage, however, a reduction of diversity of fungi with a high level of diversity of the Bacilli was observed in the ripened samples. In the drying stage, the diversity of Bacilli and fungi, especially acid-producing bacteria, reduced dramatically. Interestingly, uncultured Lactococcus sp., Microbacterium testaceum, Cochliobolus sp., and Thermoascus crustaceus were the first to be detected in the fermentation starters used in liquor production. This study revealed the microbial diversity and distributions during the shaping, ripening and drying of Daqu-making, facilitating evaluation of the hygienic conditions and aiding in the design of specific starter and/or adjunct cultures.

Microbial conversion of pyrolytic products to biofuels: a novel and sustainable approach toward second-generation biofuels

This review highlights the potential of the pyrolysis-based biofuels production, bio-ethanol in particular, and lipid in general as an alternative and sustainable solution for the rising environmental concerns and rapidly depleting natural fuel resources. Levoglucosan (1,6-anhydrous-β-d-glucopyranose) is the major anhydrosugar compound resulting from the degradation of cellulose during the fast pyrolysis process of biomass and thus the most attractive fermentation substrate in the bio-oil. The challenges for pyrolysis-based biorefineries are the inefficient detoxification strategies, and the lack of naturally available efficient and suitable fermentation organisms that could ferment the levoglucosan directly into bio-ethanol. In case of indirect fermentation, acid hydrolysis is used to convert levoglucosan into glucose and subsequently to ethanol and lipids via fermentation biocatalysts, however the presence of fermentation inhibitors poses a big hurdle to successful fermentation relative to pure glucose. Among the detoxification strategies studied so far, over-liming, extraction with solvents like (n-butanol, ethyl acetate), and activated carbon seem very promising, but still further research is required for the optimization of existing detoxification strategies as well as developing new ones. In order to make the pyrolysis-based biofuel production a more efficient as well as cost-effective process, direct fermentation of pyrolysis oil-associated fermentable sugars, especially levoglucosan is highlly desirable. This can be achieved either by expanding the search to identify naturally available direct levoglusoan utilizers or modify the existing fermentation biocatalysts (yeasts and bacteria) with direct levoglucosan pathway coupled with tolerance engineering could significantly improve the overall performance of these microorganisms.

Comparison of soil microbial communities between high and low yield organically managed orchards

TM and phospholipid fatty acids (PLFAs) analysis were used to evaluate soil microbial communities for eight typical organic orchards in Beijing, China. These included high- and low-yield agricultural sites for four types of fruit orchards: pear, peach, apple and grape. The soil properties including soil organic matter (OM), soil pH, soil total nitrogen (TN), soil available phosphorus (AP), soil available K (AK), cation exchange capacity (CEC), soil bulk density, soil porosity, microbial biomass and microbial activities were investigated. There were significant higher microbial biomass and lower bulk density in the soils of high-yield orchards than that in low-yield orchards. Differences between the paired soils of high- and low-yield orchards were highly associated with the average well colour development and total PLFAs.

Evolution of Sustainable Carbon Cycling Processes in China

Abstract This report summarizes the surveys on carbon inventories and initiatives on sustainable carbon cycling taken by RCEES. The first part of this report deals with the concept of sustainable carbon cycling, the historical evolution of carbon cycling processes in China, carbon pool enhancement, value addition, carbon sequestration and carbon balance. The second part covers the modeling of carbon dynamics, emission inventories of various carbon-containing greenhouse gases and their potential abatement measures.

The Bioconversion of Sugar Beet Pulp into Microbial Protein with Aspergillus Tamarii by Solid State Fermentation

The studies on the bioconversion of SBP into microbial protein are of interest to a number of laboratories [1-4]. This technology has a potential economic value. SBP is a major by-product of sugar refineries, it consists mainly of cellulose, hemicellulose, pectin and lignin. There are 7X 105 tons SBP (dry matter) generated in China per year. Usually,a small amount is pelletized for export, but most were thrown aside occupying land and polluting the environment. On the other hand, protein feed in short supply is a problem with the development of China’s livestock husbandry. This situation led us to choose SBP for microbial protein production research to work for a substantial industrial application.