Reserve Materials

At germination, reserve materials localized in the storage tissues (cotyledons, endosperm, and, less often, the nucellus) must be mobilized. They are the only sources of organic substances available to the seedling until it has developed its own photosynthetic apparatus. As far as this 

The essential reserve materials are carbohydrates, proteins and fats. 

Mobilization of Proteins. Mobilization of proteins involves their hydrolytic degradation to amino acids by proteases. These proteases, too, are, in part, synthesized de novo at germination just like the amylase of barley grains. 

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Polyesters are known to be produced by many bacteria as intracellular reserve materials for use as a food source during periods of environmental stress. They have received a great deal of attention since the 1970s because they are biodegradable, can be processed as plastic materials, are produced from renewable resources, and can be produced by many bacteria in a range of compositions. The thermoplastic polymers have properties that vary from soft elastomers to rigid brittie plastics in accordance with the stmcture of the pendent side-chain of the polyester. The general stmcture of this class of compounds is shown by (3), where R = CH3, n = >100, and m = 0-8. 

All these polyesters are produced by bacteria in some stressed conditions in which they are deprived of some essential component for thek normal metabohc processes. Under normal conditions of balanced growth the bacteria utilizes any substrate for energy and growth, whereas under stressed conditions bacteria utilize any suitable substrate to produce polyesters as reserve material. When the bacteria can no longer subsist on the organic substrate as a result of depletion, they consume the reserve for energy and food for survival or upon removal of the stress, the reserve is consumed and normal activities resumed. This cycle is utilized to produce the polymers which are harvested at maximum cell yield. This process has been treated in more detail in a paper (71) on the mechanism of biosynthesis of poly(hydroxyaIkanoate)s. 

It has been estimated that >90% of the carbohydrate mass in nature is in the form of polysaccharides. In living organisms, carbohydrates play important roles. In terms of mass, the greatest amounts by far are stmctural components and food reserve materials, in that order and both in plants. However, carbohydrate molecules also serve as stmctural and energy storage substances in animals and serve a variety of other essential roles in both plants and animals. 

The eytoplasm is a viscous fluid and contains within it systems of paramount importance. These are the nucleus, responsible for the genehc make-up of the cell, and the ribosomes, whieh are the site of protein synthesis, hi addihon are found granules of reserve material suehas polylydioxybutyric add, an energy reserve, and polyphosphate or volutin granules, the exact funchon of which has not yet been elucidated. The prokaiyohc nueleus or bacterial chromosome exists in the cytoplasm in the form of a loop and is not surrounded by a nuclear membrane. Bacteria cany other chromosomal elements episomes, which are portions of the main chromosome that have become isolated firm it, and plasmids, whieh may be called miniature chromosomes. These are small annular pieees of DNA whieh carry a limited amount of genetic information. 

Clayton RK, Sistrom WR (1978) In Merrick JM (ed) The photosynthetic bacteria metabolism of reserve materials. Plenum Press, New York... 

Polyhydroxyalkanoate (PHA) is a biodegradable and biocompatible thermoplastic that can be synthesized in many microoiganisms from almost all genera of the microbial kingdom. Many microoiganisms synthesize polyhydroxyalkanoates (PHAs) as intracellular carbon and energy reserve materials [1]. These microbial polyesters materials are thermoplastics with biodegradable properties [2]. PHAs are usually accumulated... 

These polymers are distinguished from cellulose by the presence of both/ -(l— 3)- and / -(l— 4)-linked D-glucosyl residues, lower molecular weights (some noncellulosic glucans are water-soluble), and susceptibility to hydrolysis by / -D-glucanases that cannot hydrolyze cellulose. Unlike cellulose, whose microfibrillar structure and structural role in the cell wall has been clearly established, the function of these polymers as structural components of the wall is still a subject of controversy there is some evidence that they are energy-reserve materials.110-201 202... 

Most (—77%) of the dry matter of a potato tuber consists of starch granules. Starch forms the reserve material in the tuber for use in respiration and sprouting. Starch granules are formed from the very early stages of tuberization, as soon as the stolon... 

The story of the discovery of chromatography is classical [16,17]. A most lucid analysis of Tswett s work from the point of view of the preparative applications of chromatography, has been written by Verzele and Dewaele [18]. The Russian botanist Tswett discovered arormd 1902 that plant pigments could be separated by eluting a sample of plant extract with a proper solvent on a column packed with a suitable adsorbent [1]. Did he name the technique chromatography because it separates pigment mixtures into a rainbow of colored bands, or because "tswett" means color in Russian, or both Nobody knows. What is remarkable, however, is the extreme care with which Tswett selected the adsorbents he used [19-21]. For the famous separation of a- and j3-carotenes, he tried 110 different adsorbents and selected inulin (a water-soluble polyfructose plant reserve material) as the... 

It is formed also by the hj drolysis of iiiulhi, a [lolysae-eharide which takes the jilacc of starch as a reserve material in the roots and tubers of many plants. Among these nuiy be mentioned decanijiaue Inula Ildcnium), dahlia. 

PHB is an envirornnentaUy degradable material belonging to the family of the PH As, polyoxoesters of hydroxyalkanoic acids. PHB was first identified in 1926 by Lemoigne as a reserve material of Bacillus megaterium [19]. Figure 1 shows the general chemical structure of PHAs (a) and the biodegradable PHB homopolyester (b). 

Simon, R.D. (1971) Cyanophycin granules from the blue-green alga Anahaena cylindrica a reserve material consisting of copolymers of aspartic acid and arginine. Proc. Natl. Acad. 

Ziegler, K., Diener, A., Herpin, C., Richter, R., Deutzmann, R., and Lockau, W. (1998) Molecular characterization of cyanophycin synthetase, the enzyme catalyzing the biosynthesis of the cyanobacterial reserve material multi-L-arginyl-poly-L-aspartate (cyanophycin). Eur. J. Biochem., 254,154-159. 

The natural polyesters, which are produced by a wide variety of bacteria as intracellular reserve materials, are receiving increased attention for possible... 

Broad interest in the possible biodegradation of synthetic polymers has developed only in recent years and primarily in response to the growing problem of the waste disposal of plastics. Essentially all biopolymers are susceptible to enzymatic degradation because the enzymatic polymerization reactions responsible for their synthesis in nature have closely related counterparts in nature for their enzymatic depolymerization what nature creates, nature can destroy . If it were not so, polymers could not be utilized as reserve materials and waste... 

The primary classification of algae is based on cellular properties the nature of the photosynthetic pigments, the chemical composition of the cell wall, nature of reserve materials and the nature and arrangement of the flagella. In terms of these characters, the major groups of algae are arranged in Table 4.1. 

Group name Pigment system Chlorophylls Other special pigments Composition of cell wall Nature of reserve materials Number and type of flagella Range of structure... 

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