Preventing microbial growth

Degassed and preswelled Bio-Gel P-6 and Sephacryl S-200 were packed in self-made glass columns (70 X 1.5 cm 140 X 1.5 cm) and equilibrated for 20 hr with H20(dest.) -t- 0.002% NaN3 to prevent microbial growth. The mass of eluted fractions was detected with a differential refractive index detector (Waters 403 RI, sensitivity 8). 

Fig. 11.2. Antibiogram test diffusion of antibiotic on agar layer, preventing microbial growth.

Of these, probably several hundred have been shown to actually cause contamination problems. Although the most important thing to be able to do is to cure and prevent microbial growth in products it is sometimes useful to know which organisms are growing in order that their origin can be determined. 

Antibiotics are required to prevent microbial growth consequent to accidental microbial contamination. Supplemental serum (often bovine or foetal calf serum, or synthetic serum... 

To study the effect of veratryl alcohol, purified lignin peroxidase or unfractionated enzyme preparation was incubated with buffer, pH 3.0 or 5.0. The concentration of veratryl alcohol in the incubation mixture was 0, 10 or 100 mM. Incubation times were 38 days at 20°C and 40 days at 4°C. The protein concentration of purified enzyme was 80/tg/ml and of unfractionated preparation 180 tg/ml. The incubation mixtures were sterile filtered to prevent microbial growth. 

Antibiotics are required to prevent microbial growth consequent to accidental microbial contamination. Supplemental serum (often bovine or fetal calf serum, or synthetic serum composed of a mixture of growth factors, hormones and metabolites typically found in serum) is required as a source of the often ill-defined growth factors required by some animal cell lines. 

Microbiocides - used to prevent microbial growth in jet fuel. The only product approved for use in jet fuel is Biobor JF. However, its use is permitted only infrequently. The maximum treat rate is 270 mg/L. 

Add sodium azide (0.02% w/v final concentration) to the serum to prevent microbial growth Thiomersal can be used for inhibition of bacteria in cases where use of sodium azide is not compatible with subsequent application of the serum (e.g., sodium azide is a potent inhibitor of horseradish peroxidase, which is often used in enzymatic detection of antigen-antibody complexes)... 

Optional) Prevent microbial growth by placing a test tube or small bottle containing toluene, sodium azide, phenyl acetate, or thymol (for non-fatty products) inside the closed chamber to prevent mold growth on the sample at aw>0.75. 

Thoroughly flush the HPLC system and column with HPLC-grade water. For storage, flush with 10% to 20% acetonitrile to prevent microbial growth. 

After the reverse osmosis process, inorganic impurities are completely removed by anion exchanger and cation exchanger. An ultraviolet light is installed and the water is circulated to prevent microbial growth. 

Antibiotics such as penicillin, streptomycin, and amphotericin B can also be added to the culture medium to prevent microbial growth. However, their use should be kept to a minimum level, because some antibiotics can have cytotoxic effect, even when high serum concentrations are used. Besides, the continuous use of antibiotics can result in the selection of resistant microorganisms, inducing a chronic contamination of the culture (Freshney, 1992). 

Less esoteric but equally important stabilizers include preservatives in liquid products to prevent microbial growth and buffers to provide an environment conducive to good stability where degradation is pH-related. Chelating agents also are used as... 

With multidose products, there is a need for use of a preservative to prevent microbial growth during the period of product use. Mixtures of ethyl- and methyl-parabens are a common choice as are phenol and m-cresol. As preservatives are used at extremely low levels (i.e., <0.1% w/w in solution), they normally would not alter the collapse characteristics of the formulation. However, since the preservative is not needed during the freeze drying process, to keep the formulation for freeze drying as simple as possible, preservatives are best introduced via the diluent intended for reconstitution. 

Prevent microbial growth when storing columns by using 50-100 % organic/ water mixtures or adding azide to gel filtration columns. 

Water treatment plants employ both primary and secondary disinfection (a) Primary disinfection achieves the desired level of microorganism kill or inactivation and (b) secondary disinfection ensures a stable residual concentration of disinfectant in the finished water to prevent microbial growth in the distribution system (4,7,14,17,18). 

The mechanism of action for diesel fuels is not well characterized due to the complexity of its petroleum hydrocarbon mixture. The presence of additives that improve fuel combustion or prevent microbial growth may contribute to toxicity. Based on research conducted with individual components of diesel fuels, the primary mechanism of action for central nervous system (CNS) depression from diesel fuel is the reversible, physical interaction of the aromatic and aliphatic hydrocarbons with cell membranes. Renal toxicity is possibly attributed to oxidative metabolites of some of the aromatic constituents. Eye and skin injury are attributable to direct irritant action and the high lipid solubility that may dissolve protective skin oils and allow penetration into the skin tissue. The dermal carcinogenesis observed in rodents subjected to chronic dermal exposure to diesel may be attributed to the genotoxic activity of PAHs and the promoting activity of repeated dermal injury. 

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