Pure culture

Triazines pose rather more of a problem, probably because the carbons are in an effectively oxidized state so that no metaboHc energy is obtained by their metaboHsm. Very few pure cultures of microorganisms are able to degrade triazines such as Atrazine, although some Pseudomonads are able to use the compound as sole source of nitrogen in the presence of citrate or other simple carbon substrates. The initial reactions seem to be the removal of the ethyl or isopropyl substituents on the ring (41), followed by complete mineralization of the triazine ring. 

Xanthan, although a gum, is derived from the pure culture fermentation of an organism, TCanthomonas campestris. The organism is filtered from the growth medium and the gum recovered by alcohoHc precipitation, followed by drying. It is composed primarily of D-glucose and D-mannose units. 

Agar, which is low in metabolizable or inhibitory substances, debris, and thermoduric spores, is ideal for the propagation and pure culture of yeasts, molds, and bacteria. Agar also meets the other requirements of ready solubiUty, good gel firmness and clarity, and a gelation temperature of 35—40°C and a gel melting temperature of 75—85°C. A clarified and purified form of the bacterial polysaccharide, geUan gum, is the only known satisfactory substitute. 

Fig. 5. Fermentative production of amino acids (140). A, pure culture B, inoculation C, boiler D, air compressor E, air filter F, seed tank G, ammonia water for pH control H, fermenter I, sterilizer , culture media K, preparation tank L, centrifugal separator M, ion-exchange column N, crystallizing...

To obtain reproducible antibiotic production by fermentation, it is necessary to obtain a pure culture of the producing organism. Pure cultures are isolated from mixed soil sample populations by various streaking and isolation techniques on nutrient media. Once a pure culture has been found that produces a new antibiotic typically on a mg/L scale, improvement in antibiotic yield is accompHshed by modification of the fermentation medium or strain selection and mutation of the producing organism. Production of g/L quantities may take years to accomplish. 

Addition of up to 200 ppm sulfur dioxide to grape musts is customary. Strains of S. cerevisiae and S. bayanus grown in the presence of sulfite, become tolerant of fairly high concentrations of SO2. Cultures propagated in the winery are added in Hquid suspension, usually at 1—2% of the must volume. Many strains are available in pure culture. Factors such as flocculence, lack of foaming, fast fermentation, lack of H2S and SO2 formation, resistance to sulfur dioxide and other inhibitors, and flavor production will affect strain choice. No strain possesses all the desired properties. 

The function of Jisper Uis fermentation appears to be primarily the breakdown of protein and polysaccharides by secreted proteases and amylases. Replacement oiPispergillis by chemical or enzymatic hydrolysis has no major impact on the organoleptic properties of the sauce. Likewise, inoculation with a pure culture of Ixictobacillus delbrueckii to carry out the acetic acid fermentation produces a normal product. The S. rouxii and Toru/opsis yeasts, however, are specifically required for proper flavor development. 

Dried algae meal—A dried mixture of algae cells (genus Spongiococcum separated from its culture broth), molasses, comsteep Hquor, and a maximum of 0.3% ethoxyquia. The algae cells are produced by suitable fermentation, under controlled conditions, from a pure culture of the genus Spongiococcum. 

The most important element is to ensure a pure culture of the production microorganism. 

Axenic Literally "without strangers." A system in which all biological populations are defined, such as a pure culture. 

Pure culture A eulture eontaining only one speeies of mieroorganism. 

Koli-gnippe, /. colon bacillus group, -rein-kultur, /, colon bacillus pure culture. 

Rein-kohle,/. pure coal, clean(ed) coal solid carbon, -koks, m. pure coke, clean coke. >kultur, kultivierung, /. Bact.) pure culture, pure cultivation. 

Rein-wismut, n. pure bismuth, -xylol, n. (Com.) a mixture of the three xylenes (m-xy-lene predominatiag). -zellulose, /. pure cellulose, -zucht, /. (Boct.) pure culture. >zuchthefe, /. pure-culture yeast, -ziich-tung,/. obtaining a pure culture. 

It is noteworthy that rates of corrosion in the field are often much higher than those in the laboratory with pure cultures. This emphasises the complexity of natural eco-systems . 

Solving (3.14.2.25) for initial value problems and applying pure culture media with a single species (r), gives ... 

Sterile conditions must be maintained for pure culture system. 

Sterile media are used for pure culture. The media used to culture microorganisms depend on the living conditions of the microorganisms. Media compositions must be identified... 

All laboratory operations are carried out in laminar flow cabinets in rooms in which filtered air is maintained at a slight positive pressure relative to their outer environment. Operators wear sterilized clothing and work aseptically. Antibiotic fermentations are, of strict necessity, pure culture aseptic processes, without con-tamirrating orgarrisms. 

As it leaves the still, distilled water is flee fixm microorganisms, and contamination occurs as a result of a fault in the cooling system, the storage vessel or the distribution system. The flora of contaminated distilled water is usually Gram-negative bacteria and since it is introduced after a sterilizahon process, it is often a pure culture. A level of organism up to 10 mH has been recorded. 

Pure cultures growing anaerobically with catechol and sulfate were isolated,and the carboxylation of catechol was proposed to be the initial reaction of anaerobic catechol degradation by Desulfobacterium sp. strain Cat2. Zhang and Young" proposed that the initial key reaction for anaerobic degradation of naphthalene and phenanthrene was also carboxylation. 

Lauff JL, DB Steele, LA Coogan, M Breitfeller (1990) Degradation of the ferric chelate of EDTA by a pure culture of w Agrobacterium sp. Appl Environ Microbiol 56 3346-3353. 

Attention is directed to organisms that have hitherto evaded isolation or are represented by only a few cultivated examples. Such organisms may well outnumber those that have been isolated as pure cultures, frequently using elective enrichment. A few illustrations are given below ... 

Although they have not been obtained in pure culture, chemolithotrophic anaerobic bacteria (anammox) that oxidize ammonia using nitrite as electron donor and CO2 as a source of carbon have been described. In addition, they can oxidize propionate to CO2 (Giiven et al. 2005) by a pathway that has not yet been resolved. 

Janssen PH, PS Yates, BE Grinton, PM Taylor, M Sait (2002) Improved cultivability of soil bacteria and isolation in pure culture of novel members of the divisions Acidobacteria, Actinobacteria, Proteobac-teria, and Verrucomicrobia. Appl Environ Microbiol 68 2391-2396. 

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