Agriculture Reference
In-Depth Information
7.2 THE PROBIOTIC CONCEPT AND HISTORY
Probiotics, generally defined as live microorganisms with different beneficial characteristics,
are increasingly becoming accepted as an alternative prophylactic measure for humans and
animals, either to treat pathogen-related diseases or to be used in preventive treatments. The
scientific definition of the term
probiotic
has been debated for several decades, and no legal
definition exists which might reduce the credibility of probiotic products on the market. Pro-
biotic research has mainly focused on the host's gastrointestinal (GI) tract, while applications
to other organs or host surfaces have been investigated to some extent.
Microorganisms, especially lactic acid bacteria (LAB), have long been associated with
food fermentation, one of the oldest methods of food preservation. Dating back to 3200
BC
, the Egyptians produced fermented milk and dairy products during the Pharaonic period
(Abou-Donia 2008). However, it was only a little over a century ago that understanding and
interest in the possible health benefits related to these products came about.
At the turn of the twentieth century, Metchnikoff (1907) suggested that the longevity of
Bulgarian peasants was linked to their heavy consumption of fermented milk. Following the
research of Tissier (1900) on the importance of bifidobacteria in the gut of infants, Metch-
nikoff (1907) proposed the possibility of modulating the gut microbiota and replacing harmful
microbes with beneficial microbes. He thought the beneficial effects of
feeding
fermented milk
were due to implantation and proliferation of
Lactobacillus bulgaricus
in the intestine. At
the end of the First World War, many children suffered from intestinal disorders. Encour-
aged by the work of Metchnikoff, Isaac Carasso created Danone in Barcelona in 1919 where
yogurt production took place using ferments from the Pasteur Institute. The products were
sold on prescription in pharmacies in Barcelona. Later, Rettger and Cheplin (1921) showed
that the implantation of
Lactobacillus acidophilus
in the human intestine could help com-
bat constipation, diarrhoea and other intestinal problems. This bacterium originated from the
human intestine and such indigenous bacteria were believed to be more likely to produce the
desired effect in the gut. Meanwhile, in 1917 Nissle (1918) isolated an
Escherichia coli
strain
which successfully treated acute cases of infectious intestinal disease such as shigellosis and
salmonellosis. This strain is an example of a non-LAB probiotic available today and sold as
Mutaflor®
®
(Ardeypharm GmbH, Germany).
Based on Metchnikoff's philosophy that modulation of the intestinal microbiota can con-
tribute to health and longevity by hindering putrefactive bacteria, Dr Minoru Shirota aimed to
isolate intestinal LAB that could help fight harmful bacteria in the body. In 1935, Shirota mar-
keted the probiotic strain
Lactobacillus casei
Shirota in a milk drink called Yakult in Japan
(Yakult Honsha Co., Ltd) which is now available worldwide. In the early 1950s a group of
physicians, the Association for Microbial Therapy, led by Hans Kolb, Helmut Mommsen and
Hans Peter Rusch, explored treatments with microbes to prevent the deleterious effects of
antibiotics (Rusch 2002). In 1957, Gordon and colleagues indicated that a successful lacto-
bacilli treatment required the strain to be non-pathogenic, of intestinal origin, and capable of
establishing itself in the gut following its application as a large number of viable cells (10
7
-10
9
g
-1
). They investigated the bacteriological effects of a
Lb.acidophilus
product on the intestinal
microbiota of patients receiving an oral antibiotic and observed a pronounced drop in staphy-
lococcal numbers at a later stage of the probiotic-antibiotic treatment. In the 1960s, fermented
milk products containing
Lb. acidophilus
were promoted by the dairy industry. In the follow-
ing decades, other intestinal
Lactobacillus
species with beneficial properties were marketed:
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