In the earth ecosystems microorganisms are very important and indispensible for maintenance of homeostasis and ecological balance. These are tiny, microscopic and archaea to the naked eye but are omnipresent with diverse functions. They include bacteria, fungi, archaea or protists and viruses. Most microorganisms are single-celled, or unicellular, but some are multicellular like fungi. Microorganisms are critical to nutrient recycling in ecosystems as they act as decomposers. In earlier times, people used to consider them as disease causing agent but later it was proved that some microbes are pathogenic to plants and animals but most are vital to humans and the environment, as they participate in the Earth's element cycles as well as fulfilling other vital roles in virtually all ecosystems, such as recycling other organisms' dead remains, waste products through decomposition, producing antibiotics and other bioactive materials etc.

Recently scientists have discovered that for health benefit and maintenance of gut micro flora, some microbes are responsible by killing the harmful ones inside our body, producing vitamins, maintenance of proper pH. So, microorganisms and their formulations are administered to the body for better health benefits.

Probiotics

According to FAO/WHO, probiotics are: "Live microorganisms which when administered in adequate amounts confer a health benefit on the host". Lactic acid bacteria (LAB) and bifidobacteria are the common types of microbes used as probiotics; but certain yeasts and bacilli may also be helpful. Probiotics are commonly known as fermented foods with specially added active live microorganisms; such as in yogurt as dietary supplements. Probiotics are also available in supplement form as capsules, liquid and chewable. There are many different strains of probiotics available in the market mainly of Lactobacillus and Bifidobacterium.

Probiotics Organisms:

Probiotic cultures naturally occur in certain fermented foods. Some commonly used probiotics microbes are: Bifidobacterium animalis, Bifidobacterium longum, Lactobacillus acidophilus, Lactobacillus paracasei, Lactobacillus johnsonii, Lactobacillus plantarum, Lactobacillus reuteri, and Saccharomyces boulardii.

Commonly available Marketed Foods as probiotics

• Yogurt
• Kefir
• Aged cheeses
• Kimchi
• Sauerkraut
• Miso
• Tempeh
• probiotic-fortified juices, chocolates, flour and cereal

Health benefits

Health is defined as physical, mental and physiological calmness/relief from all stresses and maintenance of proper body growth. Diseases are the most disturbing factor in human health and health care service hence stands 1st for human care. Usual intake of chemically synthesized medicines and antibiotics make a man more aged and deficient in natural immunity to fight against diseases. So, in recent trends use of natural assets like beneficial microbes that can alter the disease conditions without disturbing the host is the potential strategy in health care for improving human health. the beneficial functions are: modulate immune function, metabolise carcinogenic agents, inactivating enterotoxins, improved nutrient absorptivity, reduction of serum cholesterol and provide a direct barrier to invasion of the gut by pathogenic organisms etc.

Other beneficial functions of Probiotic microbes

Production of Vitamin: One of the major benefits of having probiotics microbes in fermented food or by capsules is the capacity to synthesize vitamins. In vitro studies and in humans have documented the capacity of some probiotics strains to synthesize Vitamin k, folic Acid and and vitamin-B12.
Eczema: Researchers found a roughly 20% reduction in the rate of atopic dermatitis (from around 34% in the children in these trials to 26%).

A study at University College Cork in Ireland showed that a diet including milk fermented with Lactobacillus bacteria prevented Salmonella infection in pigs and use of Lactobacillus casei DN-114001 in yoghurt can reduce diarrhea in children. In one of the study it was found that Lactobacillus rhamnosus JB-1 showed lower levels of stress and anxiety than control in human and mice

Side effects: the dark side

In some situations, consuming probiotics is critically harmful. The dutch medical society reported that the consumption of a mixture of six probiotic bacteria increased the death rate of patients with predicted severe acute pancreatitis and some may cause allergies. Some hospitals have reported the case of septicaemia, which is a potentially fatal disease caused by the consumption of probiotics by people with lowered immune systems. One of the major problem is probiotics taken orally can be destroyed by the acidic conditions of the stomach and hence number of micro-encapsulation techniques are being developed to address this problem.

Conclusion

Now research has been going on for better use and efficiency of probiotics and mostly focused on its molecular biology, metabolic engineering and biotechnological potential of Lactobacillus strains and Bifidobacteria. The application of modern whole genome mapping is providing insights into bifidobacterial evolution, while also revealing genetic functions that may explain their presence in the particular ecological environment of the gastrointestinal tract, their mode of action and disease discrepancy.

About Author / Additional Info:
The author is doing Ph.D at IIT-Kharagpur in department of biotechnology.