The Essential Roles of Beneficial Bacteria in Health, Agriculture, and Environment

Beneficial bacteria play essential roles in various ecosystems, including the human body. Some examples include:

Human Gut Microbiota

1. Lactobacillus: Found in yogurt and other fermented foods, Lactobacillus helps in digestion, boosts the immune system, and produces lactic acid, which inhibits the growth of harmful bacteria.
2. Bifidobacterium: Predominant in the intestines, Bifidobacterium aids in breaking down dietary fiber, producing vitamins, and preventing infections by competing with pathogenic bacteria.

Soil and Plant Health

1. Rhizobium: This bacterium forms symbiotic relationships with leguminous plants, fixing atmospheric nitrogen into a form that plants can use, thus enhancing soil fertility.
2. Azotobacter: Free-living nitrogen-fixing bacteria that contribute to soil fertility by converting atmospheric nitrogen into ammonia, which plants can then use for growth.

Fermentation and Food Production

1. Streptococcus thermophilus: Used in the production of yogurt and cheese, this bacterium ferments lactose, producing lactic acid, which gives yogurt its tangy flavor and thick texture.
2. Saccharomyces cerevisiae: Although a yeast, it often works in conjunction with bacteria in fermentation processes. It is essential in baking, brewing, and winemaking.

Bioremediation

1. Pseudomonas putida: Known for its ability to degrade environmental pollutants, such as oil spills and industrial waste, thereby cleaning up contaminated environments.
2. Deinococcus radiodurans: Noted for its resistance to radiation, it is used in bioremediation to treat nuclear waste.

Health Supplements

1. Escherichia coli Nissle 1917: A non-pathogenic strain of E. coli used as a probiotic to treat gastrointestinal disorders like inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS).
2. Bacillus coagulans: Known for its ability to form spores, making it a robust probiotic used in various supplements to improve gut health and boost immunity.

These beneficial bacteria contribute significantly to human health, agricultural productivity, environmental sustainability, and industrial processes. Their diverse roles underscore the importance of bacteria in maintaining ecological balance and promoting overall well-being.
The Essential Roles of Beneficial Bacteria in Health, Agriculture, and Environment

Agrobacterium tumefaciens in genetic engineering

GM crops were introduced in the U.S. in the mid-1990s. The term genetically modified (GM), as it is commonly used, refers to the transfer of genes between organisms using a series of laboratory techniques for cloning genes, splicing DNA segments together, and inserting genes into cells.

The method of transformation to generate genetically modified can be divided into two major categories: indirect and direct DNA delivery.

*Indirect method: the new DNA is introduced into the plant cell via bacteria, usually Agrobacterium tumefaciens or less commonly Agrobacterium rhizogenes.

*Direct method: In this transformation methods, the new DNA is introduced without an intermediate host and the most commonly used direct transformation method is biolistic transformation.

Genetic engineering and tissue culture are necessary to create a transgenic plant; genetic engineering to introduce the transgene (gene from another species) into the plant cell and tissue culture to regenerate the transformed cell into a whole plant.

Bacteria have in general two different types of DNA: chromosomal DNA and plasmid DNA. Chromosomal DNA is a very long molecule arranged in a chromosome, like in cells with nucleus (eukaryotes) and plasmid DNA is a small and circular DNA molecule. Plasmids are very useful for genetic engineering.

Agrobacterium tumefaciens is a soil-borne bacterium that, in nature, is capable of inserting a defined fragment of its DNA into the genome of dicotyledonous plants. The bacterium has the ability to introduce new genetic material into the plant cell. The genetic material that is introduced is called T DNA (transferred DNA) which is located on a Ti plasmid. A Ti plasmid is a circular piece of DNA.

Agrobacterium tumefaciens is a bacterium naturally able to transfer a part of its plasmid DNA into the cells of wounded plants. This extraordinary property –the ability to transfer DNA from one kingdom (bacteria) to another one (vegetal)– is unique and molecular biologists have used it to transfer selected genes into plant cells.

The natural ability to alter the plant’s genetic makeup was the foundation of plant transformation using Agrobacterium.

Some potential applications of GM crop technology are:
•Nutritional enhancement: Higher vitamin content; more healthful fatty acid profiles
•Stress tolerance: Tolerance to high and low temperatures, salinity, and drought;
•Disease resistance
Agrobacterium tumefaciens in genetic engineering

Saturated fatty acid: Butyric acid

It is an acid produced by the bacterial degradation of fiber in the colon. It is carboxylic acid, which forms an oily colorless liquid that solidifies at 8 °C and boils at 164 °C. It is soluble in water, ethanol and ether.

There are several bacterial strains producing butyric acid, which belong to the genera Clostridium, Butyribacterium, Butyrivibrio, Sarcina, Eubacterium, Fusobacterium and Megasphera.

Most butyric acid–producing bacteria ferment glucose, hexose, pentose, and oligo- and polysaccharides and form acetic acid in addition to butyric acid as their major fermentation products.

Butyric acid occurs in milk, and butter contains 3.3 percent butyric acid. Butyric acid and other shot-chain fatty acids are taken up by the intestine to be use for energy. Butyric acid is an important energy source of the cells lining the colon, where it seems to assist their normal development and maintainance.
Saturated fatty acid: Butyric acid

Food contamination by bacteria

Most of the bacteria are transmitted via food and water as a result of contamination with feces.

The main bacteria that cause food infections via colonization in the intestinal via colonization in the intestinal tract are Salmonella, Listeria monocytogenes, Yersinia enterocolitica and Shigella.

None of the bacteria can multiply in food or water or indeed outside the body of the host in which they developed. If they occur in food or water, one hopes that they will be inactivated or killed before they can infect a consumer or the vehicle.

There are a number of reasons and sources which result in the prevalence of bacterial contamination in food products, such as:
*Premises which are difficult to clean
*Lack of staff discipline
*Incorrect staff and product flow
*Poor air quality
*Incorrect direction of air movement

Food that is cooked and then not contaminated before being served is unlikely to serve as a vehicle for most of the bacteria.

Salmonella is the second most common cause of illness traced to contaminated foods and water. Foods most susceptible to Salmonella contamination are meat, fish, poultry, eggs and dairy products.

Much of the bacterial contamination of foods in restaurants, commissary kitchens and commercial processors are due to the poor personal hygiene of workers. Failure to wash hands after using the bathroom, sneezing and coughing into food, and picking noses and skin blemishes can all transmit pathogenic bacteria to food.
Food contamination by bacteria 

Staphylococcus aureus bacteria

The bacterium that causes staphylococcus poisoning is Staphylococcus aureus, the same bacterium that causes white-head pimples, infections, boils, and carbuncles.

Staphylococcus aureus is one of the most dangerous types of bacteria because of the many serious infections it can cause and because of the difficulty in treating these infections.

These cells are spherical or ovoid in shape, non-motile and liquid cultures, arrange themselves in grapelike clusters, in small groups, in pairs or in short chains.

They grow best in the presence of air (oxygen) but they also grow in the absence of air. They will grow in media or in foods that contain as much as 10% salt (NaCl). When this organism grows in foods they produce a toxin that can be filtered away from foods and the bacterial cells.

There are three major contamination scenarios existing:
* Staphylococcus aureus frequently associated with dairy cows and is leading cause of intramammary infection

*The second major source is recontamination by food handlers carrying enterotoxin-producing Staphylococcus aureus in their noses or on their hands

*Air, dust and biofilm in difficult-to-access niches in primary and secondary food production facilities can also serve as source of Staphylococcus aureus to foods.

The toxin is not destroyed by cooking. Every year in the United States, roughly 400,000 hospital patients are infected by Staphylococcus aureus.

Symptoms include vomiting and diarrhea that occur shortly after ingestion of Staphylococcus aureus toxin-contaminated food.
Staphylococcus aureus bacteria

Effects of microorganisms on food

Foods undergo deterioration to varying degrees in organoleptic properties, nutritional value, safety and esthetical appeal.  The term food deteriorations, is often associated with advanced spoilage.

Bacteria, molds and yeasts are the main causes of the spoilages of unpreserved foods, with bacteria playing the major role in the spoilage of meats, poultry, dairy, and fish products.

Mold and yeast play the major role in the spoilage of fruits and vegetables. The changes in foods due to microbial action can be classified into two types: undesirable changes and desirable changes.

These microorganisms do not cause disease but they spoil food by growing in the food and producing substances which alter the color, texture and odor of the food, making it unfit for human consumption.

All bacteria associated with foods are small. Most are of the order of one to a few micrometers in length and somewhat smaller than this in diameter. All bacteria can penetrate the smallest openings; many can pass through the natural pores of an egg shell once the natural bloom of the shell is worn.

Yeasts are somewhat larger, of the order of 20 um or so in individual cell length and about a third this size in diameter.

Typically, the effects of temperature, pH, and the acidulants, water activity and the humectants, oxygen availability, redox potential and identity and concentration of inhibitory agents are among the variables that must be considered when assessing whether microorganisms will pose a problem in particular food system.
Effects of microorganisms on food

Growth conditions for bacteria

Microorganisms grow when they have the right nutrients and conditions for growth. Bacteria need these conditions to grow:

Food
high protein foods are often contaminated at the time of purchase. Using safe food practices destroys the bacteria. Acidity: bacteria prefer low-acid environments. Some bacteria do survive an acidic environment.

Bacteria use an enormous range include various sugars and either carbohydrates, amino acids, sterols, alcohols, hydrocarbons, inorganic salts and carbon dioxide.

Time
Potentially hazardous foods should not remain in the danger zone for more than four hours during the entire food handling process.

Temperature
The temperature danger zone is 40 degrees F to 140 degrees F.

Oxygen
Many bacteria grow bets in the present of oxygen (aerobic organism). Some bacteria grow without oxygen- anaerobic. However, both types of bacteria cause foodborne illness.

Others grow equally well under either aerobic or anaerobic conditions.

Moisture
Bacteria grow best in a moist environment.
A high proportion of the mass of a bacterium is water, and during growth, nutrients and waste products enter and leave the cell. Bacteria can grow only in or on materials which have adequate free or available water.

pH
Most bacteria grow best at near pH7 (neutral), and the majority cannot grow under strongly acidic or strongly alkaline solution.
Growth conditions for bacteria

Microbial Grouping

Microbial Grouping
The microbial groups important in foods consist of several species and types of bacteria, yeasts, molds and viruses.

Bacteria, yeasts, molds and viruses are important in food for their ability to cause foodborne diseases and food spoilage to produce food and food ingredients.

Many bacterial species and some molds and viruses, but not yeasts are able to cause foodborne disease.

Most bacteria, molds and yeasts, because of their ability to grow in foods (viruses cannot grow in foods, can potentially cause food spoilage.

Several species of bacteria, molds and yeasts are considered safe of food grade or both and are used to produce fermented foods and food ingredients.

Among the four major groups, bacteria constitute the largest group. Because of their ubiquitous presence and rapid growth rate even under condition where yeast and molds cannot grow, they are considered the most important in food spoilage and foodborne disease.

Prion or proteinaceous infectious a particles have been identified to cause transmissible spongiform encephalopathies (TSEs) in humans and animals.
Microbial Grouping

Bacterial Food Poisoning

Bacterial Food Poisoning
The following bacteria frequently cause food poisoning:
-Salmonella
-Staphylococcus aureus
-Clostridium perfringes
-Bacillus cereus

The following bacteria cause food poisoning less frequently:
-Clostridium botulinum
-Some strains of Escherichia coli

All bacteria have two names. The generic name is written first and with a capital letter, e.g. Clostridium, Bacillus.

The specific name is written with a small letter after generic name, e.g. perfringes, cereus.

Bacteria with the same generic name have similar characteristics, e.g. shape, oxygen requirements, enterotoxin production and spore formation.

There are approximately 2000 species of the Salmonella genus (e.g. Salmonella typhimurium, Salmonella enteriditis, Salmonella hadar, Salmonella newport) but most of them cause food poisoning it is usual to talk about Salmonella food poisoning without distinguishing which species is actually cause.

Salmonella, Staphylococcus aureus, Clostridium perfringes and Bacillus cereus are all common cause of food poisoning in the UK and many other countries.
Bacterial Food Poisoning