Cultivation of Lactobacilli

Culture Media for Food & Beverages Testing

For cultivating bacteria of the genus Lactobacillus as part of quality assurance in food and beverages manufacturing, Merck provides a range of selective culture media. These high quality media for the enrichment, isolation and enumeration of lactobacilli are available in a variety of formulations as dehydrated culture media in form of granules.

Merck’s uniquely granulated culture media are both convenient and safe: The granules cause significantly less dust than powdered media, leading to less inhalation of hazardous media components that can cause allergic responses. In addition, granules minimize the contamination of the work environment.

Like all Merck media, our culture media for cultivating lactobacilli meet the highest industry performance standards as described in ISO 11133 and are quality controlled according to stringent standards. This guarantees the high quality and consistency of our products.

Lactobacilli: Partly Useful, Partly Harmful

Lactobacilli belong to the lactic acid bacteria, a group of microorganisms whose name is derived from the ability of most of its species to convert lactose and other sugars to lactic acid. Lactobacillus is gram-positive and facultative anaerobic or microaerophilic rod-shaped bacteria with over 180 species. Some lactobacilli are used for food production, for example yoghurt, cheese, sauerkraut and beer.

Many lactobacilli are aerotolerant (despite the complete absence of a respiratory chain) and heterofermentative. Some species of Lactobacillus have a very high hydrogen peroxide tolerance and do not need iron for growth. On the basis of their metabolism, lactobacilli can be divided into three groups: Obligately homofermentative, facultatively heterofermentative and obligately heterofermentative strains.

Lactobacilli make up a small proportion of the gastrointestinal flora of humans and occur in vaginas where they can restore the balance of the vaginal eco-system. Because they are highly tolerant of low pH values and can maintain these, they protect the vaginal eco-system from gram-negative and gram-positive bacteria.

Although lactobacilli have many positive properties, some species have been associated with tooth decay, characteristically causing existing carious lesions to progress. Other lactobacilli, however, seem to prevent streptococci from inducing dental caries. This can occur when probiotics allow lactobacilli to populate niches on teeth.