MICROBIOLOGY

ENVIRONMENTAL APPLICATIONS OF MICROORGANISMS: Microorganisms mitigate a multitude of impacts that result from human use of the natural resources of the planet. First and foremost, the essential role of microorganisms in the treatment of waste water is critical to the well being of life on Earth. Bio-remediation, bio-mining, and microbial desulfurization of coal are other large-scale processes in which important positive  environmental outcomes are achieved by directly exploiting the combined  metabolic capabilities of naturally occurring communities of microorganisms. In such applications, the functioning of a particular microbial community can be influenced through the manipulation of conditions (e.g., nutrients, oxygen tension, temperature, agitation). 1)  WASTE WATER TREATMENT:         Living organisms consist of about 70% water. A human being, for instance, has to consume an average of 1.5 L/day to survive...

SINGLE CELL PROTEIN: The term single-cell protein, or SCP, describes the protein-rich cell mass  derived from microorganisms grown on a large scale for either animal or  human consumption. SCP has a high content of protein containing all  the essential amino acids. Microorganisms are an excellent source of SCP  because of their rapid growth rate, their ability to use very inexpensive raw  materials as carbon sources, and the  uniquely high efficiency, expressed  as grams of protein produced per  kilogram of raw material, with which  they transform these carbon sources  to protein.  In spite of these advantages, only one SCP product approved for  human consumption has reached  the market. This product is “mycoprotein,” the processed cell mass  preparation from the filamentous  fungus Fusarium venenatum . We   consider here the positive nutritional properties of this product and examine the many concerns th...

FOOD TECHNOLOGY:  MONENSIN                 Monensin is the most widely used compound fed to cattle to increase feed efficiency. In feedlot cattle, a dosage of 350 mg/day led to an improvement in feed efficiency of approximately 6%. In grazing cattle, the average daily gain increased by 15%. Monensin produces these outcomes by changing the makeup of the bacterial population in the rumen, thereby influencing the balance of the end products of ruminal fermentation metabolism.  Monensin is produced by the bacterium Streptomyces cinnamonensis.  It  is a member of a large and important class of polyketides, the poly ether  ionophores.  The compound is toxic to many bacteria, fungi, protozoa, and higher organisms. The pKa of the carboxyl group in monensin is  7.95, so at the acidic pH of the rumen, the uncharged lipophilic molecule  accumulates in cell membranes of bacteria sensitive to this ion...

FOOD TECHNOLOGY: PREPARATION OF FERMENTED FOODS: The use of microorganisms to produce fermented foods has a very long history. Microbial fermentation is essential to production of wine,beer,bologna,  buttermilk, cheeses, kefir, olives, salami, sauerkraut, and many more  . The metabolic end products produced by the microorganisms  flavor fermented foods. For example, mold-ripened cheeses owe their distinctive flavors to the mixture of aldehydes, ketones, and short-chain fatty  acids produced by the fungi.  Lactic acid bacteria are widely used to produce fermented foods.  These organisms are also of particular importance in the food fermentation industry because they produce peptides and proteins(bacteriocins)  that inhibit the growth of undesirable organisms that cause food spoilage and the multiplication of food borne pathogens. The latter include  Clostridium botulinum (the cause of botulism) and    Listeria   monocytogene s...

AGRICULTURE:  CONTROL OF PATHOGENIC BACTERIA, FUNGI,AND PARASITIC NEMATODES   The cell walls of many plant pests, such as insects and fungi, contain chitin (poly-N-acetylglucosamine) as a major structural component. Many bacteria (e.g., species of Serratia, Streptomyces, and Vibrio ) produce chitin degrading enzymes (chitinases). The control of some fungal diseases by such bacteria has been correlated with the production of chitinases. Genes encoding chitinases from several different soil bacteria have been cloned  into Pseudomonas fluorescens ,an efficient colonizer of plant roots.The effectiveness of these recombinant strains in controlling fungal disease is not yet known. BACILLUS SUBTILIS STRAINS AS BROAD-SPECTRUM   MICROBIAL PESTICIDES Selected B . subtilis strains are widely accepted as broad-spectrum microbial pesticides. Strains of the common soil bacterium B. subtilis secrete a  formidable array of compounds, which together display...

TAXOL: Microbial endophytes (bacteria and fungi) are an enormous, highly diverse component of the microbial world. Plant endophytes live in plant tissues between living plant cells but generally can be isolated and cultured independent of the host. For some endophytes, there is evidence that genetic exchange takes place in both directions between the plant and the endophyte. Such exchange raises the possibility that higher plant pathways for the synthesis of complex organic molecules that have desirable biological  activities might be transferred to their endophytes. The story of the highly effective anticancer drug taxol provides proof of the validity of this notion. Taxol, a highly substituted diterpenoid with multiple asymmetric centers was isolated in 1965 from the Pacific  yew ( Taxus brevifolia ). In human cells, taxol prevents the depolymerization  of microtubules during cell division. It has the same effect in fungi. Consequently, in nature, taxol is a fu...