Screening of tea saponin-degrading strain to degrade the residual tea saponin in tea seed cake.

Although tea seed cake (TSC) possesses high nutritional value, its high content of tea saponin (TS) limits its potential as feed. This study aimed to degrade TS in TSC by saponin-degrading strain and used a multistrains fermentation method to improve its nutritional value and palatability. Three saponin-degrading strains were isolated from Oleum Camelliae mill soil and identified as Citrobacter sp. FCTS301, Pantoea sp. FCTS302, and Enterobacter sp. FCTS303. Single-factor experiment showed that Citrobacter sp. FCTS301 had the highest degradation rate of TS. Response surface analysis for Citrobacter sp. FCTS301 indicated that the optimum culture conditions were as follows: initial pH of 7.2, culture temperature of 34.2 °C, inoculation amount of 7.3%, the agitation rate of 150 rpm, and the TS concentration of 10.0 g/L. Under these conditions, the maximum degradation rate was 82.6%. The fermentation process of TSC was obtained by a multistrains fermentation experiment. Considering the protein content, crude fiber degradation rate, and TS degradation rate of each group, the optimum inoculum amount of strains included Citrobacter sp. FCTS301, Aspergillus oryzae NCUF414, Saccharomyces cersvisiae NCUF306.5, and Lactobacillus plantarum NCUF201.1(5%, 0.5%, 1.0%, and 1.5%). After TS was degraded efficiently, fermented TSC can be presumed a potential feed raw material.

Enhancement of marinacarboline A biosynthesis by optimizing the riboflavin supplement in marine derived Nocardiopsis flavescens CGMCC 4.5723.

OBJECTIVES: To improve the bioproductivity of secondary metabolites of marine derived Nocardiopsis flavescens CGMCC 4.5723 by enhancing its riboflavin supplement. RESULTS: The NfRibA, type II guanosine triphosphate (GTP) cyclohydrolase (GCH II) of Nocardiopsis flavescens CGMCC 4.5723, was biochemically identified and showed that NfRibA could efficiently catalyze the first step of riboflavin biosynthesis to hydrolyze GTP into 2, 5-diamino-6-ribosylamino-4(3H)-pyrimidinedione 5'-phosphate (DARPP) with Km value of 160.11 ± 26.81 µM in vitro. The overexpression of NfribA could obviously increase riboflavin bioproduction to the titers of 0.41 ± 0.19 mg/l by comparing with the wild type counterpart. Consequently, this rise of riboflavin bioproduction did not disturb the expression of genes involved in marinacarboline A biosynthesis, but could significantly enhance its bioproduction with the titer of 5.5 ± 0.17 mg/l through comparing with wild type control. CONCLUSIONS: Optimization of riboflavin supplement could be a new promising strategy in actinomycetic marinacarboline A exploitation.

Morphological Observations and Fatty Acid Composition of Indoor-Cultivated Cordyceps sinensis at a High-Altitude Laboratory on Sejila Mountain, Tibet.

Cordyceps sinensis, a caterpillar entomopathogenic fungus-host larva complex, is a rare medicinal herb found in the Qinghai-Tibetan Plateau and its surrounding high-altitude areas. The alternation of generations in the life cycle, whatever the fungus or its host insect, requires special growth conditions. However, it is difficult to simulate the growth conditions of C. sinensis, which hinders its artificial cultivation. In this work, the life cycle from the host larva to C. sinensis was observed in an indoor-cultivation laboratory at 4,200 m a.s.l. on Sejila Mountain, Tibet. Comparative examinations between indoor-cultivated and wild C. sinensis demonstrated that the indoor-cultivated C. sinensis preferred to germinate multiple long, slim stromata at diverse positions on dead larvae, including but not limited to their heads. Their fatty acid composition shows a significant difference in the levels of polyunsaturated fatty acids (PUFAs). In indoor-cultivated C. sinensis, PUFAs constituted 24.59% and 49.43%, respectively, of neutral and polar lipids; meanwhile, in wild C. sinensis, PUFAs represented 34.34% and 61.25% of neutral and polar lipids, respectively. These observations and fatty acid data suggest that environmental factors, particularly temperature, soil pressure and light intensity, strongly affect the growth of C. sinensis. Our new findings may provide important information for improving techniques for the large-scale artificial cultivation of C. sinensis.

Isolation and characterization of a novel hydrocarbon-degrading bacterium Achromobacter sp. HZ01 from the crude oil-contaminated seawater at the Daya Bay, southern China.

Microorganisms play an important role in the biodegradation of petroleum contaminants, which have attracted great concern due to their persistent toxicity and difficult biodegradation. In this paper, a novel hydrocarbon-degrading bacterium HZ01 was isolated from the crude oil-contaminated seawater at the Daya Bay, South China Sea, and identified as Achromobacter sp. Under the conditions of pH 7.0, NaCl 3% (w/v), temperature 28 °C and rotary speed 150 rpm, its degradability of the total n-alkanes reached up to 96.6% after 10 days of incubation for the evaporated diesel oil. Furthermore, Achromobacter sp. HZ01 could effectively utilize polycyclic aromatic hydrocarbons (PAHs) as its sole carbon source, and could remove anthracene, phenanthrene and pyrence about 29.8%, 50.6% and 38.4% respectively after 30 days of incubation. Therefore, Achromobacter sp. HZ01 may employed as an excellent degrader to develop one cost-effective and eco-friendly method for the bioremediation of marine environments polluted by crude oil.