MICROBIOLOGY

ZARAGOZIC ACIDS (SQUALESTATINS): Over 93% of the cholesterol in the human body is located in cells, where it performs indispensable structural and metabolic roles. The remaining 7% circulates in the plasma,where it contributes to atherosclerosis (formation of plaques on the walls of the arteries supplying the heart, the brain, and other vital organs).  For delivery to tissues, plasma cholesterol is packaged in lipoprotein particles;two thirds is associated with low-density lipoprotein(LDL) and the balance with the   high-density lipoprotein. The disorder familial hypercholesterolemia occurs in one in 500 of the population and results in elevated plasma levels of cholesterol-bearing LDL. Male heterozygotes with dominant familial hypercholesterolemia have an 85% chance of occurrence of heart attacks (myocardial infarction) before the age of 60. (Homozygotes of either sex die of heart disease at an early age). A much larger number of people, who do ...

SECONDARY METABOLITES AS A SOURCE OF DRUGS: Microorganisms produce a huge number of small molecular weight compounds that are broadly described as secondary metabolites. A traditional approach to the discovery of new, naturally occurring bio active molecules utilizes “screens.” A screen is an assay procedure that allows testing of numerous compounds for a particular activity. Tens of thousands of secondary metabolites and other compounds have been examined for biological activity in various organisms and many have proved invaluable as antibacterial or  anti fungal agents,anticancer drugs,immunosuppressants,herbicides,tools for research, and the like. Genetically modified microorganisms have been engineered to produce such compounds in large amounts. Among these, antibiotics are the secondary metabolites considered among the most important to human therapeutics, and the most extensive use of screens is in the search for compounds with selective toxicity for bacter...

One can be a good biologist without necessarily knowing much about microorganisms, but one cannot be a good microbiologist without a fair basic knowledge of biology! – Stanier, R. Y., Doudoroff, M., and Adelberg, E. A. (1957).The Microbial World. p. vii, Englewood Cliffs, NJ: Prentice-Hall, Inc. Microorganisms, whether cultured or represented only in environmental DNA samples, constitute the natural resource base of microbial biotechnology. Numerous prokaryotic and fungal genomes have been completely sequenced and the functions of many genes established. For a newly sequenced prokaryotic genome, functions for over 60% of the open reading frames can be provisionally assigned by sequence homology with genes of known function. Knowledge of the ecology, genetics, physiology, and metabolism of thousands of prokaryotes and fungi provides an indispensable complement to the sequence database. This is an era of explosive growth of analysis and manipulation of microbial genomes as...

PATHWAYS FOR THE SYNTHESIS OF  PRIMARY AND SECONDARY METABOLITES OF INDUSTRIAL IMPORTANCE: The main source of carbon and energy in industrial media is carbohydrates. In recent  times hydrocarbons have been used. The catabolism of these compounds will be discussed briefly because they supply the carbon skeletons for the synthesis of primary  as well as for secondary metabolites. The inter-relationship between the pathways of  primary and the secondary metabolism will also be discussed briefly. Catabolism of Carbohydrates: Four pathways for the catabolism of carbohydrates up to pyruvic acid are known. All four pathways exist in bacteria, actinomycetes and fungi, including yeasts. The four pathways are the Embden-Meyerhof-Parnas, the Pentose Phosphate Pathways, the Entner Doudoroff pathway and the Phosphoketolase. Although these pathways are for the breakdown of glucose. Other carbohydrates easily fit into the cycles. (i) The Embden-M...

TROPHOPHASE-IDIOPHASE RELATIONSHIPS IN THE  PRODUCTION OF SECONDARY PRODUCTS:  From studies on Penicillium urticae the terms trophophase and idiophase were introduced to distinguish the two phases in the growth of organisms producing secondary metabolites. The trophophase (Greek, tropho = nutrient) is the feeding phase during which primary metabolism occurs. In a batch culture this would be in the logarithmic phase of the growth curve. Following the trophophase is the idio-phase (Greek, idio = peculiar)  during which secondary metabolites peculiar to, or characteristic of, a given organism are synthesized.  Secondary synthesis occurs in the late logarithmic, and in the stationary, phase. It has been suggested that secondary metabolites be described as 'idiolites' to distinguish them from primary metabolites. ROLE OF SECONDARY METABOLITES IN THE  PHYSIOLOGY OF ORGANISMS PRODUCING THEM: Since many industrial microbiological products result from second...

MICROBIOLOGY : METABOLIC PATHWAYS FOR BIOSYNTHESIS OF INDUSTRIAL ... : THE NATURE OF METABOLIC PATHWAYS: In order to be able to manipulate microorganisms to produce maximally materials of economic importance...

MICROBIOLOGY : METABOLIC PATHWAYS FOR BIOSYNTHESIS OF INDUSTRIAL ... : THE NATURE OF METABOLIC PATHWAYS: In order to be able to manipulate microorganisms to produce maximally materials of economic importance...

THE NATURE OF METABOLIC PATHWAYS: In order to be able to manipulate microorganisms to produce maximally materials of economic importance to humans, but at minimal costs, it is important that the physiology of the organisms be understood as much as is possible. In this section  relevant elements of the physiology of industrial organisms will be discussed. A yeast cell will divide and produce carbon dioxide under aerobic conditions if offered a solution of glucose and ammonium salts. The increase in cell number resulting from the growth and the bubbling of carbon dioxide are only external evidence of a vast number of chemical reactions going in the cell.  The yeast cell on absorbing the glucose has to produce various proteins which will form enzymes necessary to catalyze the various reactions concerned with the manufacture of proteins, carbohydrates, lipids, and other components of the cell as well as vitamins which will form coenzymes. A vast array of enzymes are pr...

METAGENOMICS: Metagenomics is the genomic analysis of the collective genome of an assemblage of organisms or ‘metagenome.’Metagenomics describes the functional and sequence-based analysis of the collective microbial genomes contained in an environmental sample.  Other terms have been used to describe the same method, including environmental DNA libraries, zoolibraries, soil DNA libraries, eDNA libraries, recombinant environmental libraries, whole genome treasures, community genome, whole genome shotgun sequencing. The definition applied here excludes studies that use PCR to amplify gene cassettes or random PCR primers to access genes of interest since  these methods do not provide genomic information beyond the genes that are amplified. Many environments have been focus of metagenomics, including the soil, the oral cavity,feces, and aquatic habitats, as well as the hospital metagenome a term intended to encompass the genetic potential  of organisms in hospitals...