General physiology and metabolism

The strictly anaerobic beer-spoilage bacteria share a few metabolic and physiological features. For instance, they produce acetic and propionic adds from simple sugars. However, clear differences exist in their nutrition and physiology, which is reflected in their beer-spoilage ability and can be exploited for their detection and identification. The key characteristics discriminating the beer-spoilage species from each other are shown in Tables 9.1 and 9.2. 

Characteristic Pectinatus cererisiiphilus Pectinatus frisingensis Pectinatus haikarae Selenomonas lacticifex Propionispira paucivorans Propionispira raffinosivorans 

Colonies visible on solid media 1-2 days 3 days 4 days 

Megasphaera cerevisiae strains form a uniform group in terms of utilized carbon sources that include arabinose, fructose, lactic acid and pyruvic acid (Engelmann Weiss, 1985). 

Megasphaera Not known Acetic, butyric, caproic, isobntyric, isovaleric, propionic, and valeric acids, H2S Rancid, rotten egg + 

---

We generally try to use as few descriptors as possible and to relate them wherever possible to the known or expected physiological and metabolic behavior of the test compounds. 

For in vitro toxicity studies and assessment of the barrier function, drug transport, cell physiology, and metabolism as well as the development of delivery systems, cell culture models provide powerful systems for scientific research. As the corneal epithelium is the main barrier for ocular penetration, various corneal epithelial cell cultures were established besides the corneal constructs that mimic the whole cornea and serve as reductionist models for the ocular barrier. In general, two types of cell culture models are available primary cell cultures and immortalized, continuous cell lines. 

Steroid Hormones. Generally, steroid hormones arc mctaholically short-lived steroids produced in small amounts by various endocrine glands. They serve as chemical messengers that regulate a variety of physiological and metabolic activities in vertehrates. Steroid hormones bind to soluble, intracellular receptor molecules. In the nucleus of... 

Relatively little is known of the physiology and metabolism of insect parasitoids. Though it is generally assumed that the maturing parasitic hymenopteran eggs take up host hemolymph components and ions through its thin wall (17. 25) it has been shown that some parasitoids rely on their protein synthetic machinery for growth (25. 26). Much of this synthesis occurs after the parasitoid is associated with the host (27). 

---