Symbiobacterium thermophilum is a symbiotic Gram-negative and tryptophanase-positive thermophile. It is an uncultivable bacterium isolated from compost that depends on microbial commensalism. It does not grow by itself under standard culture conditions; however, when cocultured with Bacillus sp., it propagates. S.thermophilum proliferates under both aerobic and anaerobic conditions (Ref.1, 2 & 3).The cell wall of this Gram-negative bacterium constitutes a multifaceted fabric that is essential for survival, shape, and integrity. Macromolecular assemblies of cross-linked peptidoglycan, polyanionic TAs (Teichoic Acids), and surface proteins function within this envelope. A key step in peptidoglycan layer assembly and deposition in the cell wall of S. thermophilum is[..]

Lactic acid bacteria play important roles in food conservation because of their fermentative ability and contribute to the equilibrium of the gastrointestinal tract microbiota. Lactobacillus johnsonii (L. johnsonii)  is commonly found in the gastrointestinal tract and adhere to intestinal cells. Such interactions of bacteria with the gastrointestinal tract contribute to its protection against pathogenic microorganisms. A close association between the bacteria and their environment undoubtedly results in adaptation of their metabolic capacities (Ref.1).D-Alanine occurs to the extent of 1 to 2 per cent of the dry cells of various lactic acid bacteria including L. johnsonii and L-Alanine is essential for L. johnsonii growth. The naturally occurring L-Alanine isomer[..]

Group-A Streptococcus pyogenes remains an important human pathogen responsible for a variety of suppurative infections, including pharyngitis, scarlet fever, impetigo, and cellulitis and for nonsuppurative sequelae, such as acute rheumatic fever, acute glomerulonephritis, and reactive arthritis (Ref.1). S. pyogenes strains are grouped into two classes on the basis of post infectious sequelae associated with each strain, Class-I is responsible for rheumatic fever and Class-II is responsible for acute glomerulonephritis. S. pyogenes strain SSI-1 (Serotype M3) is among the most prevalent in terms of involvement in severe invasive infections (Ref.2 & 3).As is the case in other Gram-positive bacteria, the cell wall of S. pyogenes is associated with an array of proteins[..]

Listeria monocytogenes(L. monocytogenes) is a Gram-positive bacterium widely spread in nature and responsible for sporadic severe infections in humans and other animal species. This pathogen is a facultative intracellular microorganism capable of invading and surviving in most host cells, including epithelial cells and macrophages. L. monocytogenes strain F2365 (Serotype 4b) has been isolated from Jalisco cheese outbreak in 1985 in California (Ref.1).The naturally occurring L-Alanine isomer is racemized to its D-form through the action of a class of enzymes called dal (alanine racemase). This enzyme is ubiquitous among prokaryotes and with very few exceptions are absent in eukaryotes. It catalyzes the racemization of L-Alanine and D-Alanine, using Pyridoxal[..]

Group-A Streptococcus pyogenes remains an important human pathogen responsible for a variety of suppurative infections, including pharyngitis, scarlet fever, impetigo, and cellulitis and for nonsuppurative sequelae, such as acute rheumatic fever, acute Glomerulonephritis, and reactive arthritis (Ref.1). S. pyogenes strains are grouped into two classes on the basis of post infectious sequelae associated with each strain, Class-I is responsible for rheumatic fever and Class-II is responsible for acute glomerulonephritis. S. pyogenes strain MGAS8232 (Serotype M18) was isolated from a patient with acute rheumatic fever. The Serotype M18 is among the most prevalent in terms of involvement in severe invasive infections (Ref.2, 3 & 4).As is the case in other Gram-positive[..]

Rhizobium, Bradyrhizobium, Mesorhizobium, Sinorhizobium and Azorhizobium-known as Rhizobia-are Gram-negative, nitrogen-fixing bacteria of agronomic importance because they perform nitrogen-fixing symbiosis with leguminous plants. Nodule formation and the subsequent nitrogen-fixation result from a series of interactions controlled by the exchange of molecular signals between symbiotic bacteria and host plants followed by expression of genes from both symbiotic partners. Mesorhizobium loti (M .loti) is able to form determinant-type globular nodules and perform nitrogen-fixation on several Lotus species (Ref.1).The cell wall of these Gram-negative bacteria constitutes a multifaceted fabric that is essential for survival, shape, and integrity. Macromolecular assemblies of[..]

Streptococcus thermophilus is one of the most economically important lactic acid bacteria used in the manufacture of yogurt and cheeses. This bacterium belongs to the group of GRAS (Generally Recognized as Safe) bacteria which is an exception in the Streptococcus genus. S. thermophilus is used, along with Lactobacillus sp., as a starter culture for the manufacture of several important fermented dairy foods, including yogurt and Mozzarella cheese. Its use has increased significantly during the past two decades, as a result of the tremendous increase in consumption of these products (Ref. 1 & 2).The cell wall of these Gram-positive bacteria constitutes a multifaceted fabric that is essential for survival, shape, and integrity. D-Alanine occurs to the extent of 1 to 2[..]

Staphylococcus aureus are Gram-positive nonmotile coccus that grows in aerobic and anaerobic conditions, in which it forms grape-like clusters. S. aureus is an opportunistic pathogen and the major causative agent of numerous hospital- and community-acquired infections. It produces numerous toxins including super antigens that cause unique disease entities such as toxic-shock syndrome and staphylococcal scarlet fever. Its genetic plasticity has facilitated the evolution of many virulent and drug-resistant strains, presenting a major and constantly changing clinical challenge. S. aureus COL is an early methicillin-resistant isolate (Ref.1).The cell wall of S. aureus is 50 percent peptidoglycan by weight consisting of alternating polysaccharide subunits of[..]

Ralstonia solanacearum (previously named Pseudomonas solanacearum) is a devastating, soil-borne plant pathogen and the causal agent of bacterial wilt, one of the most important bacterial diseases worldwide. Hundreds of different plant species, including many important agricultural crops such as potato, tomato, banana, pepper, and even trees such as eucalyptus are affected by this vascular pathogen (Ref.1). It is a model system for the dissection of molecular determinants governing pathogenicity. It exhibits a strong and tissue-specific tropism within the host, specifically invading, and highly multiplying in, the xylem vessels of the roots. R. solanacearum is a Beta-Proteobacterium and thus belongs to a group of bacteria whose genomic organization is still poorly[..]

Photorhabdus sp. are facultatively anaerobic gram negative rods, nonsporulating and chemoorganotrophic heterotrophs with respiratory and fermentative metabolisms. They are included in the family of Enterobacteriaceae belonging to Group-5 and Sub-group1. Almost all species of Photorhabdus are entomopathogenic. The bacterium Photorhabdus luminescens is pathogenic to a wide range of insects (Ref.1). Bacteria cells are surrounded by a protective exoskeleton called the , peptidoglycan layer which is a cross-linked mesh-like macromolecule consisting of glycan strands interlinked by short peptides. A key step in peptidoglycan layer assembly and deposition in this bacterial cell wall is the subsequent enzymic cross-linking of one peptidoglycan strand to an adjacent one in cell[..]

Sinorhizobium meliloti (formerly Rhizobium meliloti), is a common Gram-negative soil and rhizosphere bacterium, that forms nitrogen-fixing nodules on the roots of certain genera of leguminous plants, including Medicago, Melilotus and Trigonella sp. Inside the nodules, differentiated bacteria called bacteroids fix atmospheric nitrogen (i.e. reduce N2 into NH3) to the benefit of the plant. Nodule formation and the subsequent nitrogen-fixation result from a series of interactions controlled by the exchange of molecular signals between symbiotic bacteria and host plants followed by expression of genes from both symbiotic partners. S. meliloti surface polysaccharides, including exopolysaccharides, lipopolysaccharides, capsular polysaccharides, and cyclic Beta-Glucans are[..]

Oceanobacillus iheyensis is an alkaliphilic and extremely halotolerant Bacillus-related species isolated from deep-sea sediment. It is also known as 'small ocean bacillus pertaining to the Iheya Ridge' from where it was isolated. O. iheyensis grows at depths of up to 3,000 m. The bacteria thrive under high hydrostatic pressure and grow optimally at about 30 degrees Celsius (Ref. 1).The cell wall of this bacterium is a unique biopolymer, containing both D- and L-Amino acids. The terminal peptide is D-Alanine although other amino acids are present as D-isomers and this is the only known biological molecule that contains D-Amino acids, which are responsible for the building of peptidoglycan. A key step in peptidoglycan layer assembly and deposition is the[..]