The Alpha-Proteobacteria is predominantly responsible for the degradation of organosulfur compounds, including the algal osmolyte dimethylsulfoniopropionate. Silicobacter pomeroyi carries out many organic sulfur transformations that occur in natural bacterial communities in the surface ocean. The bacterium converts dimethylsulfoniopropionate to both dimethylsulfide and methanethiol. Through these pathways, the sulfur in dimethylsulfonio propionate is either released as volatile sulfur to the atmosphere, or retained in the marine food web in the form of S-containing amino acids (Ref.1 & 2). The cell wall of these bacteria is a unique biopolymer, containing both D- and L-Amino acids. The terminal peptide is D-Alanine although other amino acids are present as[..]

Nitrosomonas europaea is a Gram-negative obligate chemolithoautotroph, which derives all its energy and reductant for growth from the aerobic oxidation of ammonia to nitrite. The bacterium participates in the biogeochemical Nitrogen cycle in the process of nitrification (Ref.1). A key step in peptidoglycan layer assembly and deposition in the cell wall of N.europaea is the subsequent enzymic cross-linking of one peptidoglycan strand to an adjacent one in cell wall growth. D-Alanine is a central molecule in this peptidoglycan assembly and cross-linking. L-Alanine is also a product of several other metabolic pathways like Cyanoamino Acid Metabolism, Selenoamino Acid Metabolism, Alanine and Aspartate, and D-Arginine and D-Ornithine Metabolism. The naturally occurring[..]

Methanotrophs are a unique group of Gram-negative bacteria that grow aerobically on methane and utilize methane as the sole source of carbon and energy. Methanotrophs such as Methylococcus capsulatus(M. capsulatus) are responsible for the oxidation of biologically generated methane, and they are therefore of great environmental importance in reducing the amount of this greenhouse gas released to the Earth's atmosphere (Ref.1). A key step in peptidoglycan layer assembly and deposition in the cell wall of M. capsulatus is the subsequent enzymic cross-linking of one peptidoglycan strand to an adjacent one in cell wall growth. D-Alanine is a central molecule in this peptidoglycan assembly and cross-linking (Ref.2). L-Alanine is also a product of several other metabolic[..]

Listeria monocytogenes(L. monocytogenes) is a Gram-positive facultative intracellular bacterial pathogen that elicits a strong cellular immune response following infection and therefore has potential use as a vaccine vector. However, while infections by L. monocytogenes are fairly rare and can readily be controlled by a number of antibiotics, the organism can nevertheless cause meningitis and death, particularly in immunocompromised or pregnant patients. L. monocytogenes EGD-e (Serovar 1/2a) is a derivative of strain EGD (Ref.1). As in most Gram-positive bacteria, the cell wall of L. monocytogenes is composed of a thick peptidoglycan containing two types of anionic polymers: (i) the TAs (Teichoic Acids), which are covalently linked to the peptidoglycan; and (ii) the[..]

Lactic acid bacteria are a heterogeneous group of microorganisms that convert carbohydrates into lactic acid. They comprise both pathogens (such as Streptococcus pneumoniae or Streptococcus pyogenes) and useful bacteria (such as Streptococcus thermophilus and Lactococcus lactis (L. lactis), which were used for millennia in milk fermentation). In nature, L. lactis occupies a niche related to plant or animal surfaces and the animal gastrointestinal tract. It is believed to be dormant on the plant surfaces and to multiply in the gastrointestinal tract after being swallowed by a ruminant. In contrast, "domesticated" species of L. lactis, used by dairy industry as starters in cheese fermentation, live in a different niche, which is defined by technological[..]

Bordetella pertussis, Bordetella parapertussis and Bordetella bronchiseptica are closely related Gram-negative Beta-proteobacteria that colonizes the respiratory tracts of mammals. B. bronchiseptica causes chronic respiratory infections in a wide range of animals. D-Alanine is a necessary precursor in the biosynthesis of cell wall in this bacterium (Ref.1).The naturally occurring L-Alanine isomer is racemized to its D-form through the action of a class of enzymes called alr (alanine racemase).using Pyridoxal 5'-Phosphate (Vitamin-B6) as a cofactor (Ref.2). L-Alanine is also a product of several other metabolic pathways like Cyanoamino Acid Metabolism, Selenoamino Acid Metabolism, Alanine and Aspartate, and D-Arginine and D-Ornithine Metabolism. D-Alanine metabolism[..]

The genus Bordetella in the family Alcaligenaceae, comprises five species(Bordetella pertussis, Bordetella parapertussis and Bordetella bronchiseptica, Bordetella hinzii and Bordetella avium ), four of which cause infections of the upper respiratory tract in different host organisms. They are closely related Gram-negative Beta-proteobacteria Bordetella pertussis is an obligate human pathogen and is the etiological agent of whooping cough (pertussis), an acute respiratory infection more serious among infants. Annually, more than 50 million cases of pertussis, including 600,000 deaths are reported worldwide. Bordetella parapertussis, causes a mild pertussis-like disease in humans and is very closely related to B. pertussis. An animal pathogen of the Bordetella species is[..]

Bacillus species and other microbes with pH optima for growth higher than pH 9 are defined as alkaliphiles. A large number of alkaliphilic Bacillus strains producing useful enzymes, have been isolated from various environments. Bacillus halodurans(B. halodurans) is an alkaliphilic Bacillus species that grows optimally above pH 9.5. It is the second Bacillus species whose entire genomic sequence has been completely defined. B. halodurans is similar to B. subtilis in terms of genome size, G+C content, and physiological properties, except for its alkaliphilic phenotype (Ref.1).The cell wall of these Gram-positive bacteria is a unique biopolymer, containing both D- and L-Amino acids. Its basic structure is a carbohydrate backbone of alternating units of N-Acetyl[..]

Bacilli are an extremely diverse group of bacteria that include both the causative agent of anthrax (Bacillus anthracis) as well as several species that synthesize important antibiotics. Bacilli are rod-shaped, Gram-positive, sporulating, aerobes or facultative anaerobes. Bacilli exhibit an array of physiologic abilities that allow them to live in a wide range of habitats, including many extreme habitats such as desert sands, hot springs, and Arctic soils. Species in the genus Bacillus can be thermophilic, psychrophilic, acidophilic, alkaliphilic, halotolerant, or halophilic and are capable of growing at pH values, temperatures, and salt concentrations where few other organisms can survive. Due to the metabolic diversity in the genus Bacillus, Bacilli are able to[..]

Bacilli are an extremely diverse group of bacteria that include both the causative agent of anthrax (Bacillus anthracis) as well as several species that synthesize important antibiotics. Bacilli are rod-shaped, Gram-positive, sporulating, aerobes or facultative anaerobes. Bacilli exhibit an array of physiologic abilities that allow them to live in a wide range of habitats, including many extreme habitats such as desert sands, hot springs, and Arctic soils. Species in the genus Bacillus can be thermophilic, psychrophilic, acidophilic, alkaliphilic, halotolerant, or halophilic and are capable of growing at pH values, temperatures, and salt concentrations where few other organisms can survive (Ref.1, 2 & 4). Due to the metabolic diversity in the genus Bacillus,[..]

Bacilli are rod-shaped, Gram-positive, sporulating, aerobes or facultative anaerobes. Bacilli exhibit an array of physiologic abilities that allow them to live in a wide range of habitats, including many extreme habitats such as desert sands, hot springs, and Arctic soils. Species in the genus Bacillus can be thermophilic, psychrophilic, acidophilic, alkaliphilic, halotolerant, or halophilic and are capable of growing at pH values, temperatures, and salt concentrations where few other organisms can survive (Ref.1, 2 and 4). Due to the metabolic diversity in the genus Bacillus, Bacilli are able to colonize a variety of habitats ranging from soil to insects, to humans. The three species of the Group-1 Bacilli, B. anthracis, B. cereus, and B. thuringiensis, are[..]

Bordetella pertussis, Bordetella parapertussis and Bordetella bronchiseptica are closely related Gram-negative Beta-proteobacteria that colonizes the respiratory tracts of mammals. B. pertussis is a strict human pathogen of recent evolutionary origin and is the primary etiologic agent of whooping cough. D-Alanine is a necessary precursor in the biosynthesis of cell wall in this bacterium (Ref.1). The naturally occurring L-Alanine isomer is racemized to its D-form through the action of a class of enzymes called AlRs (Alanine Racemase). This enzyme is ubiquitous among prokaryotes and with very few exceptions are absent in eukaryotes (Ref.2). It catalyzes the racemization of L-Alanine and D-Alanine, using Pyridoxal 5'-Phosphate as a cofactor and is involved in[..]