What is its use? Widely used to detect human contamination, fecal contamination, pathogen survival, activity of microorganisms involved in the deterioration and post-process contamination.

MO What are indicators? A variety of microorganisms are often found in foods under study and are relatively easy to grow, such MO serve to indicate the presence of other yeasts MO: to estimate the shelf life of yogurt. Coliforms in pasteurized milk to detect flaws in the process. Presence of E. coli in meat as an indicator of fecal contamination.

Most commonly used indicator GROUP: COLIFORM. They serve as indicators of quality and also as indicators of the presence of pathogens.

Example = E. coli O157: H7

One of the most important for identification of microorganisms is observed for growth on artificial foodstuffs prepared in the laboratory. For bacteria to grow well in artificial culture medium must satisfy certain conditions such as temperature, humidity and adequate oxygen pressure and a proper degree of acidity or alkalinity. Availability of adequate nutrients

A suitable culture medium must contain at least carbon, nitrogen, sulfur, phosphorus and inorganic salts. Example = meat peptone, lactose broth

Proper consistency of the medium: solid media are now used universally for its versatility and comfort, but there are also plenty of liquid which is widely used in the laboratory.

Presence (or absence) of oxygen and other gases: A lot of bacteria can grow in an atmosphere with oxygen tension. Some can get oxygen directly from various substrates. But the strict anaerobes only properly developed in an atmosphere without oxygen.

Moisture conditions A minimum level of moisture, in the middle and the atmosphere is essential for proper development of vegetative microbial cells in cultures.

Ambient Light: Most microorganisms grow much better in the dark in the presence of sunlight.

pH: hydrogen ion concentration is very important for the growth of microorganisms. Most of them grow best in media with a neutral pH, although there are ways that require more or less acidic.

Temperature: Mesophilic microorganisms grow optimally at temperatures between 15 and 43 º C. Others, such as psychrophiles grow at 0 ° C and thermophiles at 80 ° C or even higher temperatures (hyperthermophiles).

Sterility of the medium: All culture media must be perfectly sterile.

Selective breeding methods.

Enrichment culture. The enrichment culture method is in principle and in practice very simple. Enrichment conditions are those in which an organism is implanted competition. Establishing a number of factors (sources of energy, carbon, nitrogen, hydrogen acceptor, atmosphere, light, temperature, pH, etc.) Are determined precise environmental conditions, and seeded with a mixed population, as presented in soil or sludge. EI enrichment culture to isolate microorganisms with any combination of nutritional requirements, naturally with the premise that the chosen type are present in nature.

Pure culture. Pure culture means the offspring (clone) of a single cell. The primary role of the microbiologist is to obtain pure cultures, demonstrating its purity without doubt and maintain the pure culture free of contamination. The isolation of pure culture takes place, with some exceptions, on or in solid media.

Mixed culture. Natural populations usually consist of a mixture of different microorganisms. Among them establish relationships of different types. These are based on competition for common ground as commensalism or mutualism. To study the interrelationships of this type, and others, is increasingly using batch cultures.

In the domestic economy and industry are not only used pure cultures, mixed cultures but also, some of which are also called “natural pure cultures.”


Water: is processed within the 1st hour of being sampled, but will keep refrigerated up to 24 hours.

Samples of perishable transported in cooler to a temperature no higher than 6 ° C and should be processed within 24 hours of sampling.

Flour, powder.: They can be transported at room temperature.

Environmental samples: avoiding cross-contamination and transported in airtight container.

Bulk products: sample with specialized equipment and transported in airtight container at room temperature or depending on the product concerned.

Media Preparation: All or most of the culture media label bring in their mode of preparation.

Objective: To establish the procedure for the collection, transport and handling of samples for microbiological analysis, and thereby obtain reliable results.

The food is shown mainly for 3 reasons:

The 1st Perform quality control and determine the shelf life.
2daVerificar handling techniques and hygienic.
3raSospechar poison or infection through food.


Aseptically: how to maintain the complete absence of living microorganisms in half.

Expiration date: Deadline is considered a product, stored under the conditions suggested by the manufacturer, maintains the health conditions to be met for consumption. Representative Sample: A number of units taken from a batch, which are selected at random and whose characteristics are as similar as possible to the batch from which it comes.

Witness Shows: Shows that remains in the hands of interested and available to the competent authority.

Perishables: Food group which by their nature biological, and physical chemistry, life is till 30 days, leading to the establishment of an expiration date, which must bear on its label or container.

Sampling: The procedure that is required to choose the material to be analyzed from the entire batch.

Life or shelf life: The time during which a food is safe and maintains an acceptable level of sanitary quality for consumption, under specific conditions of processing, packaging and storage.