Growth potential of cottonseed culture media for various clinically significant aerobic bacteria

Dynamic succession of substrate-associated bacterial composition and function during Ganoderma lucidum growth

Background

Ganoderma lucidum, a valuable medicinal fungus, is widely distributed in China. It grows alongside with a complex microbial ecosystem in the substrate. As sequencing technology advances, it is possible to reveal the composition and functions of substrate-associated bacterial communities.

Methods

We analyzed the bacterial community dynamics in the substrate during the four typical growth stages of G. lucidum using next-generation sequencing.

Results

The physicochemical properties of the substrate (e.g. acidity, moisture, total nitrogen, total phosphorus and total potassium) changed between different growth stages. A total of 598,771 sequences from 12 samples were obtained and assigned to 22 bacterial phyla. Proteobacteria and Firmicutes were the dominant phyla. Bacterial community composition and diversity significantly differed between the elongation stage and the other three growth stages. LEfSe analysis revealed a large number of bacterial taxa (e.g. Bacteroidetes, Acidobacteria and Nitrospirae) with significantly higher abundance at the elongation stage. Functional pathway prediction uncovered significant abundance changes of a number of bacterial functional pathways between the elongation stage and other growth stages. At the elongation stage, the abundance of the environmental information processing pathway (mainly membrane transport) decreased, whereas that of the metabolism-related pathways increased.

Discussion

The changes in bacterial community composition, diversity and predicted functions were most likely related to the changes in the moisture and nutrient conditions in the substrate with the growth of G. lucidum, particularly at the elongation stage. Our findings shed light on the G. lucidum-bacteria-substrate relationships, which should facilitate the industrial cultivation of G. lucidum.

Evaluation of a water-extracted pharmamedia agar medium for the culture of fungi

The purpose of this investigation was to determine the value of a water-extracted Pharmamedia agar medium for the culture of fungi. The growth of the fungi on this medium was compared to that on Sabouraud brain heart infusion agar. The Pharmamedia extract agar supported the growth of the 42 filamentous and yeast or yeast-like fungi that were examined. The medium was relatively clear to easily permit observation of the diagnostic microscopic and macroscopic architecture of the organisms. The Pharmamedia extract agar also permitted the conversion of the mold-to-yeast phase with Blastomyces dermatitides and Penicillium marneffei. This investigation supports the use of Pharmamedia as a culture medium for the clinical microbiology laboratory. Its relative simplicity of preparation and effective use as a culture medium, as well as a conversion medium, emphasizes its useful application for clinical mycology.

Rapid carbohydrate fermentation test for confirmation of the pathogenic Neisseria using a Ba(OH)2 indicator

The Ba(OH)2 indicator system was demonstrated to be a practical procedure in assisting clinical bacteriologists in the accurate and rapid identification of the pathogenic Neisseria from clinical specimens. This system measured the release of CO2, resulting from the metabolism of fermentable carbohydrate, as the precipitated BaCO3, by means of a spectrophotometer, The method was uncomplicated and can be performed in most clinical bacteriology laboratories.