Bacteria tests

MICq is the antibiotic concentration at which 90% of the bacteria tested ate iahibited. 

One standard test used to determine the presence of the coliform group is called the multiple-tube fermentation technique (sometimes called the presumptive test). If this test indicates the presence of these bacteria, then a confirmed test must be done. If only negative colonies or no colonies develop during this test, it is considered negative otherwise, a completed test must be undertaken. Positive results obtained in the completed test are evidence for the presence of coliform bacteria. Testing methods have been given by the APHA, and the detailed procedures contained therein should be consulted (20). 

Fowle DA, Fein JB (1999) Competitive adsorption of metal cations onto two gram positive bacteria testing the chemical equilibrium model. Geochim Cosmochim Acta 63 3059-3067... 

The ability to use azo dyes as sole energy and carbon source by bacteria to be able to reduce the azo bond aerobically by a cometabolic way has been reported [2,4]. A mixture of four structurally different dyes (Acid Red 88, Reactive Black 5, Direct Red 81, and Disperse Orange 3) was used as sole source of carbon and nitrogen to select six strains of bacteria tested for the ability to decolorize the dyes individually or in mixtures a S. putrefaciens strain was identified as the most efficient [45]. 

Three years interlaboratory comparison studies of the BL bacteria test 189... 

A method to detect upper UTI is the antibody-coated bacteria test, an immunofluorescent method that detects bacteria coated with immunoglobulin in freshly voided urine. 

ISO 11348-2 (1994) Water quality determination of the inhibitory effect of water samples on the light emission of Vibrio fischeri (luminescent bacteria test), draft, September (revised). International Organization for Standardization, Geneva... 

The toxicity requirements are established per type of industry, in terms of the maximum number of times the effluents needs to be diluted to produce a no observed effect concentration (NOEC), defined as Gf for fish, Gd for daphnia, Ga for algae, and G1 for luminescent bacteria. Testing is limited to the exposure to only the appropriate Gx level, which should not produce any observed effect [the G-value corresponds with the dilution of the effluent, expressed as the lowest dilution factor (1,2,4,...) causing less than 10% mortality]. The level of maximum allowable toxicity per industrial branch is based on the level that is considered to be attainable with state-of-the-art process and/or treatment technology. Violating the toxicity requirements results in a levy, which makes state-of-the-art compliance a more economic option [12]. 

The Permeable Cell Assay was optimized for E. coli K-12 (BW25113) (4). To investigate applications of this assay, P. fluorcscms, P. putida, C. ammoniagmcs, and C. glutumicum were tested. All bacteria were grown in LBG medium at 30°C for 24 h. The final OD of each bacterium was adjusted to 0.1, and the intensity of luminescence was measured. The intensity of luminescence from all bacteria tested with various concentrations of Triton X-100 showed saturated luminescence with 0.4% Triton X-100 (4). Both species of Corynehacterium... 

All bacteria were cultivated in a 96-deep-well plate, and their ATP synthetic activities were assayed using a 96-well format. Cellular ATP synthetic activity of C. lutamicum was highest among the bacteria tested. Activities were the mean ( = 3)... 

Fumaric Aero Inhibition. Another means of preventing malo-lactic fermentation is to add fumaric acid after alcoholic fermentation is complete (45, 46, 47,48). The inhibition is relative and its extent is dependent on the amount added. The susceptibility to fumaric acid is also dependent on the strain of malo-lactic bacteria tested (49). However, we know of no case where fumaric acid addition at the levels suggested by Cofran and Meyer (45) (about 0.05%) did not delay malo-lactic fermentation under normal winemaking conditions. This includes several experiments from our pilot winery (50). Nevertheless, we have not been hasty to recommend the use of fumaric acid as an inhibitor because 1) of the difficulty in solubilizing the acid in wine 2) we do not know the mechanism of action of its inhibition [Pilone (47, 48) has shown that the bacteria metabolize low levels of fumaric acid to lactic acid but, at inhibitory levels at wine pH, the acid is bactericidal] and 3) of the desirability of minimizing the use of chemical additives. 

After 15 min incubation, transfer 20 pi volume of the bacteria/test-product into the first well of the no. 96 plate and continue down the plate with 1 10 dilutions. Repeat for all bacteria test-products and control, and follow with colony counts. 

The following example explains how a pT-value is determined. Within a dilution series, light inhibition percentages in the luminescent bacteria test at a dilution of 1 16 are below the threshold of 20 % (see Sections 5.2 and 5.4). In exponential form, 1 16 is written as 1 24 = 2A. The negative logarithm on a base of 2 of the 1 16 dilution factor is 4, or explained differently, 2 raised to the negative 4th power corresponds to 1 16. Thus, the pT-value of 4 can be attributed to the tested material. 

Inhibition values measured at 11 different time periods in an effluent from a biological wastewater treatment plant with the luminescent bacteria test are shown in Figure 1. The pT-values of this industrial wastewater discharged into the Rhine River ranged between 4 and 12 (Tab. 3). It should be noted, however, that high values were measured prior to an internal processing change in the plant and that low values were obtained after the adjustment. 

Figure 1. Inhibition values in percent measured at multiple intervals in effluents from an industrial wastewater treatment plant with the Microtox luminescent bacteria test.

When applied for characterizing the potential toxicity of wastewater effluents, the pT-method can draw attention to certain groups of chemicals in the effluent. In Section 5.7, for example, the extremely high pT-values measured with the luminescent bacteria test (pT value = 7) and the Daphnia test (pT value = 8) indicate that chemicals eliciting these toxic effects must subsequently be identified and removed in the wastewater treatment process, so as to protect decomposers and micro-crustaceans. 

Krebs, F. (1992a) Der Leuchtbakterientest fur die Wassergesetzgebung (The luminescent bacteria test for water legislation), Schriftenreihe des Vereins fur WasserBoden- und Lufthygiene 89, 591 -624. 

ISO (1998) Water quality - Determination of the inhibitory effect of water samples on light emission of Vibrio flscheri (Luminescent bacteria test), Part 3 - Method using freeze-dried bacteria. International... 

No. Location 22 Algal Test Luminescent Bacteria Test Daphnia Test Toxi- city class ... 

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