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Determination of index of coliforms at research water

Amount of positive results of analysis of water from:   Coli-index   Coli-titer
Three small bottles for 100 ml Three small bottles for 10 ml Three small bottles for 1 ml
>333
0,9
> 1100 < 0,9

Note: Is water suitable for the use if coli-titer ≥ 333 ìë, and coli-index ≤ 3.

Task 4.

For an analysis waters, regulated of sanitary norms depending on the supposed amount of BGEC in the test of water, take away different volumes. The probed water is filtered in a filtration vehicle, for example in the vehicle of Zaitc through diaphragm filters ¹ 2 or ¹ 3, and plankton filters ¹ 6.

After filtration filter it is carried sterile pincers, not inverting, on the Endo agar, in Petri dish. A filter must densely adjoin to the surface of Endo agar. On the day of Petri dish put the number of test, volume of the filtered water, date of sowing and place in a thermostat at the temperature of 37°C on days. For this time colonies appear from settling on a filter bacterium. Take into account colonies, characteristic for coli bacillus (red with metallic brilliance and without him, pink transparent). From a few colonies of different tints prepare painting and stain them on Gram.

In the case of presence of untypical E. coli (short or long, polymorphic) additionally conduct an oxidase test which allows to distinguish the bacterium of family Enterobacteriacae from other gram-negative bacteria.

The result of analysis is expressed as coli-index which is calculated, multiplying the amount of growing’s on a filter colonies of BGEC by 1000 and divide by the volume of the filtered water. If in 1 liter of drinking-water contained more than 3 BGEC and in 1 liter of water of pools— more than 10, it testifies to fecal pollution, exceeding a norm.

Task 5.

At determination of microbial number soil is taken on a depth 10 – 15 sm a sterile knife (from different places, no less than 10 tests). From tests prepare a hinge-plate (30 g) which is brought in a retort with water (270 ml). From the got suspension prepare dilutions 104, 105. From these dilutions take 0.1 ml and mix up with 40 ml cooled 0,7 % nourishing agar. After it this mixture is outpoured in a Petri dish with a 2% nourishing agar by the second layer. The inoculation is incubated in a thermostat at 37°C. Then count the amount of colonies and determine a microbial number.



Table 4

Indexes of pollution of soil

Soil Microbial number, million in 1 g Coli-titer   Perfringes-titer
Strongly muddy ≥ 3 - 5 ≤ 0,001 ≤ 0,0001
Moderato muddy 2,5 – 3 0,01 – 0,001 0,01 – 0,0001
Poorly muddy 0,1 – 0,01 0,1 – 0,01
Clean 1 – 1,5 ≥ 1,0 ≥ 0,1

Task 6.

Kefir is a natural probiotic. It contains live active cultures of normal flora that will actually repopulate your digestive tract and aid in digestion. Kefir is superior to yogurt because yogurt is made with transient, less potent bacteria.

Kefir is a cultured milk beverage, the result of microbial action of a wide community of microorganisms present in kefir grains on milk. The microorganism’s are lodged in the grains in a polysaccharide matrix of "kefiran". The resulting beverage has a uniform creamy consistency, a slightly acidic taste caused mostly by lactic acid, some effervescence due to carbon dioxide and a minute (<2%) concentration of alcohol due to the action of yeast cells also present in the grains. Microorganisms present in the grains are called probiotic because they are beneficial to human health. There are lactobacilli, such as L. brevis, L. cellobiosus, L. acidophilus, L. casei, L. helveticus, L. delbrueckii, L. lactis, etc., lactococci, such as different subspecies of L. lactis, Streptococcus salivarius spp. thermophilus, Leuconostoc mesenteroides and L. cremoris and a variety of yeasts (fungi), such as Candida and Saccharomyces spp.

In preparation from kefir you can look Lactobacillus bulgaricum, Streptococcus lactis, Streptococcus diacetilactis, Saccharomyces kefiri, clot of protein.

Addition 1


Date: 2016-01-14; view: 1057


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PROCEDURE OF PRACTICAL SESSION | Sanitary-microbiological research of water, air, soil, food products and objects of external environmental
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