Sterilization in stages

The endoagar culture medium is not poured into test tubes. Instead it is sterilized in stages (3 times 20 minutes with intervals of 2 hours between each stage) in an Erlenmeyer flask and is then poured directly from this flask into sterile Petri dishes. The pouring out operation must be carried... 

The components listed above are heated in a flask for 20 minutes in a steam bath, filtered, cooled down and then made up to 1000 ml with demineralized water. 10 ml quantities of the broth are poured into test tubes and then sterilized in stages (3 times 20 minutes) on a steam bath. 

The stated quantities of the components are dissolved in the water by heating in a steam bath. The pH is then set to 7.2. The culture medium is either sterilized in stages (heating three times for 20 minutes in a steam bath with intervals of 24 hours between each heating process) or in an autoclave for 20 minutes at 121 C. The culture medium is then poured out into Petri dishes. 

The specialist trade also supplies dry culture media in powder form, which contain all the components which are necessary for the cultivation of microorganisms on the particular culture medium. In accordance with the recipes which are given, a definite quantity of the powder must be weighed out. A specified quantity of demineralized water, tap water or the water which is to be analyzed is then poured over this powder. This is then generally dissolved with heating and the pH is set to the desired value. After the solution has been put into test tubes or flasks, it is sterilized either in an autoclave or by sterilization in stages in a steam bath. It is always to... 

Tomato fruits (Lycopersicon esculentum Mill. var. Castlemart ) were collected from vines grown in the field at the University of California, Davis. Pericarp discs were cut from surface sterilized MG stage fruit (10). Droplets (10 n ) of test solutions (see below) were applied to the cut surface of discs and disc ethylene production was measured as described previously (11). The amounts of test materials used were based on colorimetric assay (6) of uronic acid content. 

The interpretation of sterility results is divided into two stages by the USP relative to the type of sterility failure if one occurs. If sterility failure of the test samples occurred because of improper aseptic technique or as a fault of the test itself, stage 1 may be repeated with the same sample size. Sample size is doubled in a stage 2 testing, which is performed if microbial growth is observed in stage 1 and there is no reason to believe that the test was invalid. The only absolute method to guarantee the sterility of a batch would be to test every vial or ampoule. 

Liquid product is fed to the BFS machine from a holding tank or vessel. The pathway is sterilized in place prior to receiving product, and product is sterilized by means of in-line sterilizing-grade filters. There is usually more than one stage of sterile filtration required on the product pathway. 

The requirement for sterility in parenteral products is absolute and must be borne in mind at all stages of formulation and process development. The regulatory environment now requires that parenteral products be terminally sterilized unless this is precluded, usually by reason of instability (see the section Manufacturing of Parenteral Products ). 

Phytochemicals, such as the precocenes, isolated from Ageratum houstonianum [126], interfere with JH biosynthesis. In sensitive insect species, application of these dichromenes to larval instars results in precocious metamorphosis to sterile adults or sterility in adult females following treatment. Pesticides based on these compounds would be useful in the control of insects which are primarily destructive in their immature stages. Other phytochemicals which potentially function as "antijuvenile hormones" include dimethyl sciadinonate, isolated from the leaves of avocado, Persea americana Mill [127, 128], Ingestion of this... 

The inoculum which was added to these large fermenters was developed in stages from spores stored in sterile sand or soil (cf. Figure 6.16). During this process the growing bacteria may become infected with one of several phages. These are viruses which infect bacteria. If this happens at a late stage in the transfers, or in the productive fermentation, it will result in a costly failure. 

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