Microbiology: Microbes in Daily Use 1

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A microorganism (from the Greek: μικρός, mikrós, "small" and ὀργανισμός, organismós, "organism") or microbe is a microscopic organism, which may be a single cellor multicellular organism. The study of microorganisms is called microbiology, a subject that began with Anton van Leeuwenhoek's discovery of microorganisms in 1675, using a microscope of his own design. Microorganisms are very diverse; they include all of the , namely the bacteria and archaea; and various forms of eukaryotes, comprising the protozoa, fungi, algae, microscopic plants (green algae), and animals such as rotifers and planarians. Some microbiologists also classify viruses as microorganisms, but others consider these as nonliving.Most microorganisms are microscopic, but there are some like Thiomargarita namibiensis, which are macroscopic and visible to the naked eye. Microorganisms live in every part of the biosphere including soil, hot springs, on the ocean floor, high in the atmosphere and deep inside rocks within the Earth's crust (see also endolith). Microorganisms are crucial to nutrient recycling in ecosystems as they act as decomposers. As some microorganisms can fix nitrogen, they are a vital part of the nitrogen cycle, and recent studies indicate that airborne microbes may play a role in precipitation and weather.

 Microbe is a term for tiny creatures that individually are too small to be seen with the unaided eye. Microbes include bacteria (back-tear-ee-uh), archaea (are-key-uh), fungi (fun-jeye) and protists (pro-tists). You've probably heard of bacteria and fungi before. Archaea are bacteria-like creatures that have some traits not found in any true bacteria. Protists include primitive algae (al-gee), amoebas (ah-me-buhs), slime molds and protozoa (pro-toe-zoh-uh). We can also include viruses (vye-rus-is) as a major type of microbe, though there is a debate as to whether viruses can be considered living creatures or not. 

Microscopic Worlds Microbes are extremely small, and can only be seen with a microscope. They are smaller than a human red blood cell. Millions of microbes can fit inside the eye of a needle. They are also very old. In fact, they are the oldest form of life on Earth. They roamed the Earth — in their own microscopic way — hundreds of millions of years before the dinosaurs. They live everywhere. Dig up the soil, and you will find countless microbes living there. Take a sample of air, and they are there as well. They even live inside our digestive systems. The many species of microbes can be organized in several ways. Familiar categories include the bacteria, fungi, and viruses. There are even microscopic animals — such as dust mites — which resemble tiny insects. Microbes can also be split into two groups based upon whether they have a cell nucleus. This membrane-bound part of the cell encloses the genetic material. In addition, microbes can be classified by how they obtain and process their food. Or how they react to oxygen. Some microbes need oxygen to survive. Others — like the ones living inside our digestive system — are killed by oxygen.

 Importance of Microbes Microbes are essential components of every ecosystem. They produce the oxygen that we need to live. They break down garbage and dead organisms. They produce nutrients that plants need to grow. They even help us digest our food. In addition to these natural activities, microbes are needed for making foods like bread, wine and beer. Scientists also use microbes for practical applications. Microbes at a sewer treatment plant help breakdown the waste. Microbes can also be used to change the genetic composition of plants and animals. This gives them new traits, such as resistance to pesticides. Microbes are probably better known for the diseases that they cause. AIDS, tuberculosis, bacterial meningitis and the common cold are all caused by microbes. Greater understanding of how microbes live and function, though, has enabled scientists to prevent and treat diseases. Vaccines, antibiotics and other drugs are powerful tools for reducing illnesses caused by microbes. Not all discoveries, however, were planned. Penicillin, an antibiotic produced by a fungus, was discovered largely by accident. In spite of the many scientific discoveries, washing and proper sanitation are still important tools in preventing diseases caused by microbes. 

 Science of Microbiology The invention of the microscope in the late 1600’s sparked the science of microbiology — the study of microbes. Scientists that study microbes are called microbiologists. Early on, microbiology focused on observing the tiny organisms visible through the microscope lenses. Over time the techniques for collecting and growing microbes improved. Microbiologists then began to understand how microbes reproduce, develop and cause disease. While we now know that bacteria can cause diseases, scientists only started to prove this in the 19th century. Since its early beginnings, microbiology has expanded beyond just the microbes that affect human health. Microbiologists now study the entire range of microbes. The branches of microbiology can be defined by the organisms being studied. Microbiology can also be divided along more broad areas. These include areas such as evolution, genetics and applied fields, like industrial microbiology. 

 Microbiology Techniques Microbes are challenging organisms to study. You can’t see them with the naked eye, so microscopes are needed to observe them directly. The earliest observations of microbes were made with simple lenses. Microscopes were then built with a combination of lenses. This enabled scientists to see more details and smaller organisms. Other types of microscopes and techniques were later developed. These provided scientists with a greater understanding of the microscopic world. Observing microbes is only one of the challenges faced by microbiologists. Only a small fraction of microbes can actually be grown in a laboratory. This means that countless species of microbes have yet to be identified. Scientists can, however, study the microbes that are difficult to grow using other methods, such as DNA sequencing. Microbiologists are also able to alter the genetic material inside a microbe. This changes how the microbe behaves and functions.

Animal Products plays an important role in the socio- economic life of India. It is a rich source of high quality of animal products such as milk, meat and eggs. India has emerged as the largest producer of milk with 16.43 percent share in total milk production in the world. India accounts for about 4.95 percent of the global egg production and also the largest population of milch animals in the world, with 112.9 million buffaloes, 157 million goat and 74.5 million sheep. Exports of animal products represent an important and significant contribution to the Indian Agriculture sector. The export of Animal Products includes Buffalo meat, Sheep/ Goat meat, Poultry products, Animal Casings, Milk and Milk products and Honey etc. 

Butter Fresh	Butter MilK
Butter Oil	Fresh Cheese
Milk & Cream in Powder	Milk for Babies
Other Fat	Skimmed milk powder
Other milk power	Whole Milk
Ghee

Curd is a sour milk preparation. Curd or dahi or yoghurt is eaten as such with salt or sugar or added to other preparations. The butterfat is removed from dahi by churning and used to make ghee. Curd has almost the same calorific value of cow's milk. 40 percent of lactose is converted to lactic acid. It has 3.1gm of protein, 4gm of fat, 149mg of calcium, and 93mg of phosphorous.

Curd is reported to have better nutritive value than milk. Though there is no increase in the fat or protein content of milk during fermentation, the digestibility of curd is more than that of milk. The calcium and phosphorous contents of curd are more easily assimilated. Curd contains more vitamins than milk. During curd formation the lactose of milk is converted into lactic acid. There is some breakdown of protein increasing the non-protein nitrogen. The fat globules coalesce and distribute them selves on the top. Physically during curd formation milk proteins are jellied and a thin exudates of clear serum on the curd is seen.

The organism involved in curd formation belongs to the group of lacto bacillus and streptococci. Each of these organisms produces different levels of acidity. The formation of consistently good quality curd depends upon the use of the right type of starter. A starter culture containing a combination of lactobacillus and lactococcus organisms gives good results. Starters containing yeasts, molds and gas forming organisms spoil the quality of curd. When they are present, a product with a homogeneous texture or good aroma will not be obtained. There will be cracks and gas bubbles and the curd will be of poor quality and taste.

 cheeses  There are lots of different types of cheese and no standard way of classifying them. Some cheeses also fall into more than one category. They can be classified by age, country of origin, fat content, dairy content, manufacturing methods, texture and special characteristics. Steven Jenkins, a renowned American cheese expert and member of the Confrérie des chevaliers du Taste Fromage (an elite society of cheese connoisseurs), suggests the following categories [source: Jenkins]:

• Fresh
• Soft-ripened
• Washed-rind
• Natural-rind
• Blue-veined
• Uncooked, pressed
• Cooked, pressed
• Processed

Fresh cheeses are the most basic. They're uncooked, unaged and sometimes still contain whey (the liquid part of milk). They don't keep very long and therefore need to be eaten soon after they're made. This cheese category includes mozzarella, cottage cheese, ricotta, cream cheese, farmer cheese, mascarpone and queso fresco. Fresh cheese is characterized by its soft, creamy texture and mild taste.

Fresh cheeses are the most basic. They're uncooked, unaged and sometimes still contain whey (the liquid part of milk). They don't keep very long and therefore need to be eaten soon after they're made. This cheese category includes mozzarella, cottage cheese, ricotta, cream cheese, farmer cheese, mascarpone and queso fresco. Fresh cheese is characterized by its soft, creamy texture and mild taste.

Soft-ripened cheeses are semisoft in texture and sometimes have a white, or "bloomy," rind. This is created with the application of molds (more on this later). Soft-ripened cheeses are usually a little more flavorful and buttery than fresh cheeses, but they're still very mild. Camembert and Brie are examples of this type of cheese.

Most varieties of "stinky" cheese, like Limburger, are washed-rind, or monastery cheese. These cheeses have reddish-orange rinds. The "stink" comes from being washed in a liquid, such as salted water, wine or beer, during the ripening phase. The washing encourages the growth of bacteria and mold, which gives the cheese a very strong smell and taste.

Some cheeses have rinds that form naturally, without the introduction of molds or bacteria. These natural-rind cheeses are usually aged and are heavier than other types of cheeses. Many of them are made from raw milk, and they include English Stilton and the French fromage de chèvre.

English Stilton is a blue-veined cheese. These cheeses resemble marble, with bluish-green veins crossing through the pale cheese. The veins are mold cultures, introduced during the cheesemaking process. Depending on the type of cheese, the mold may give it a very strong flavor. Maytag Blue, Gorgonzola and Roquefort are other examples of blue-veined cheese.

Cheddar, one of the most well-known cheeses, is an uncooked, pressedcheese. This means that the curds have not been heated and the cheese has been pressed to give it a very compact, dense texture. Cooked, pressed cheese has its curds heated before being pressed. Parmigiano-Reggiano, Gruyère and Emmental are all cooked, pressed cheeses. Within this category are pasta filata, cheeses like provolone in which the curds are stretched.

Processed cheese isn't technically a cheese but a byproduct of the cheesemaking process. It may be made with scraps of cheese, but processed cheese can also include whey, cream, water, dyes, gums and other ingredients. It has a long shelf life, melts easily and can be made in spreadable varieties. This type of cheese includes American cheese (although this name is also used for some American-made cheddars) as well as products like Cheez Whiz, Velveeta and spray cheese. However, not all processed cheese is American-made -- the French La Vache Qui Rit (Laughing Cow) is also processed.

Cheese (with the exception of processed cheese) can be made with milk from mammals other than cows. Roquefort, a blue-veined cheese, and Pecorino Romano, a cooked, pressed cheese, are both made with sheep's milk. Many varieties of cheese, including soft-ripened and blue-veined, can be made with goat's milk.

Regardless of the source, milk is the main component in cheesemaking. In the next section, we'll look at how all of these cheeses are made.