To track protein expression, localization, or conformational changes as components of cellular signaling pathways, biologists need general tools for the in vivo site-specific labeling of proteins with fluorophores or other useful probes. Fluorescein and its derivatives have been the most popular fluorescent derivatization reagents for covalently labeling proteins because of their relatively high absorptivities, excellent fluorescence quantum yields and high water solubilities. In addition, fluorescein-protein conjugates are usually not susceptible to precipitation. Fluorescein has an excitation maximum that closely matches the 488 nm spectral line of the argon ion laser, making it the predominant fluorophore for confocal laser scanning microscopy and flow cytometry applications. Many widespread optical filter sets are designed to excite efficiently and detect fluorescein's fluorescence. Fluorescein can most commonly be introduced into a protein through in vitro modifications with suitable amine-reactive reagents, such as N-hydroxysuccinimidylfluorescein.

Production of therapeutic recombinant proteins from mammalian systems is one of the fastest growing segments of the pharmaceutical market. Several analyses indicate that demand will eventually outpace production of these proteins. This imminent shortage has served to emphasize the need to improve on the yield that can be obtained from the systems currently in place. The majority of these proteins are produced in Chinese Hamster Ovary (CHO) cells, while the remainder are produced in a variety of other cell types including mouse myelomas NSO & SP2/0, baby hamster kidney (BHK) and a variety of others. CHO cells were first cultured in the late 1950's after their isolation from a chinese hamster (Cricetulus griseus) ovary epithelial tumor. Produced in CHO, tPA was the first of these recombinant proteins to receive approval for therapeutic use. Many changes to the process have occurred since that time, including changes to the cells, the growth medium and the reactor conditions to improve from that first venture. CHO remains the dominant force in biopharmaceutical production because it represents a cell line that is capable of incorporating the appropriate post-translational modifications, while at the same time maintaining the characteristics ideal for production culture.

Pseudomonas fluorescens is a plant growth-promoting rhizobacterium. Certain strains of Pseudomonas fluorescens produce secondary metabolites that are toxic to plant-pathogenic fungi. It is not surprising, therefore, that the production of antifungal compounds enhances the ability of these bacteria to suppress a variety of plant diseases and in some instances contributes to the ecological competence of the producing strain within the rhizosphere. Specific strains of Pseudomonas fluorescens & Pseudomonas putida provide biological control of fungal plant pathogens and deleterious rhizobacteria with concomitant positive growth responses above & beyond simple amelioration of disease. The ability of these strains to act as biological control agents has been attributed to their ability to rapidly & competitively colonize roots & to produce siderophores (iron-binding compounds) and antibiotics. The first of these biological control formulations based on Pseudomonas has been placed into the field for commercial control of damping-off fungi on cotton. Pseudomonads produce a host of antibiotics including phenazines, pyrroles, pseudomonic acid, pyo compounds and amino acid-containing antibiotics.

Microorganisms were among the first tools used for the discovery of biologically active compounds. From recombinant DNA technology emerged important role for microorganisms in pharmaceutical research, the expression of heterologous proteins for therapeutic products or for in vitro high throughput screens (HTSs). Recent developments in cloning, genetics & expression systems have opened up new applications for recombinant microorganisms in screening for nonantibiotic compounds in HTSs. These screens employ microorganisms that depend upon the function of a heterologous protein for survival under defined nutritional conditions. Compounds that specifically target the heterologous protein can be identified by measuring viability of the microorganism under different nutrient selection. Advantages of this approach include a built-in selection for target selectivity, an easily measured end point that can be used for a multitude of different targets, and compatibility with automation required for HTSs. Mechanism-based HTSs using recombinant microorganisms can also address drug targets that are not readily approachable in other HTS formats, including certain enzymes, ion channels & transporters, and protein:: DNA & protein::RNA interactions.

Any solid refuse or trash encountered in either an industrial or municipal environment is refuse derived. As used herein, the solid refuse may contain minor amounts of fly ash. Preferably, the solid refuse is what is known as clean trash, in that it consists substantially of solid, cellulose-based materials, such as paper, kraft paper, cardboard, computer print-outs & cards, and paper towels, plastic-based, such as styrofoam & other soft plastics, metallic-based materials, such as acco-type fasteners, ring binders, paper clips, staples, binder clips & other sundry type soft metal wastes & glass. Preferably, the refuse or clean trash is substantially cellulose-based material & is substantially free of glass and metallic materials. Refuse-derived fuel (RDF) is prepared from municipal solid waste. Noncombustible materials such as rocks, glass & metals are removed, and the remaining combustible portion of the solid waste is chopped or shredded. RDF facilities process between 100 and 3000 tons of MSW per day.