Streptomyces beigongshangae sp. nov., isolated from baijiu fermented grains, could transform ginsenosides of Panax notoginseng

A Gram-stain-positive actinomycete, designated REN17T, was isolated from fermented grains of Baijiu collected from Sichuan, PR China. It exhibited branched substrate mycelia and a sparse aerial mycelium. The optimal growth conditions for REN17T were determined to be 28 °C and pH 7, with a NaCl concentration of 0 % (w/v). ll-Diaminopimelic acid was the diagnostic amino acid of the cell-wall peptidoglycan and the polar lipids were composed of phosphatidylethanolamine, phosphatidylinositol, an unidentified phospholipid, two unidentified lipids and four unidentified glycolipids. The predominant menaquinone was MK-9 (H2), MK-9 (H4), MK-9 (H6) and MK-9 (H8). The major fatty acids were iso-C16 : 0. The 16S rRNA sequence of REN17T was most closely related to those of Streptomyces apricus SUN 51T (99.8 %), Streptomyces liliiviolaceus BH-SS-21T (99.6 %) and Streptomyces umbirnus JCM 4521T (98.9 %). The digital DNA-DNA hybridization, average nucleotide identity and average amino acid identify values between REN17T and its closest replated strain, of S. apricus SUN 51T, were 35.9, 88.9 and 87.3 %, respectively. Therefore, REN17T represents a novel species within the genus Streptomyces, for which the name Streptomyces beigongshangae sp. nov. is proposed. The type strain is REN17T (=GDMCC 4.193T=JCM 34712T). While exploring the function of the strain, REN17T was found to possess the ability to transform major ginsenosides of Panax notoginseng (Burk.) F.H. Chen (Araliaceae) into minor ginsenoside through HPLC separation, which was due to the presence of β-glucosidase. The recombinant β-glucosidase was constructed and purified, which could produce minor ginsenosides of Rg3 and C-K. Finally, the enzymatic properties were characterized.

Actinomycetospora termitidis sp. nov., an insect-derived actinomycete isolated from termite (Odontotermes formosanus)

Strain Odt1-22T, an insect-derived actinomycete was isolated from a termite (Odontotermes formosanus) that was collected from Chanthaburi province, Thailand. Strain Odt1-22T was aerobic, Gram-stain-positive, and produced bud-like spore chain on the substrate hypha. According to chemotaxonomic analysis, strain Odt1-22T contained meso-diaminopimelic acid in peptidoglycan and the whole-cell hydrolysates contained arabinose, galactose, glucose, and ribose. The major menaquinone was MK-8(H4). The diagnostic phospholipids were diphosphatidylglycerol, hydroxyphosphatidylethanolamine, phosphatidylethanolamine and phosphatidylglycerol. Phylogenetic analysis based on 16 S rRNA gene sequence revealed that strain Odt1-22T was identified to the genus Actinomycetospora and showed high similarity values with A. chiangmaiensis DSM 45062 T (99.24%), A. soli SF1T (99.24%) and A. corticicola 014-5 T (98.17%). The genomic size of strain Odt1-22T was 6.6 Mbp with 73.8% G + C content and 6355 coding sequences (CDSs). The genomic analysis, strain Odt1-22T and closely related species A. chiangmaiensis DSM 45062 T, A. soli SF1T and A. corticicola DSM 45772 T displayed the values of average nucleotide identity-blast (ANIb) at 83.7-84.1% and MUMmer (ANIm) at 86.6-87.0%. Moreover, the results of digital DNA-DNA hybridization values between strain Odt1-22T and related Actinomycetospora species were 45.8-50.5% that lower than the threshold value of commonly used to delineate separated species level. On the basis of phenotypic, chemotaxonomic, and genotypic data, strain Odt1-22T represented a novel species within the genus Actinomycetospora, for which the name Actinomycetospora termitidis sp. nov. is proposed. The type strain of the species is Odt1-22T (= TBRC 16192 T = NBRC 115965 T).

Saccharopolyspora oryzae sp. nov., isolated from rhizosphere soil of the wild rice species Oryza rufipogon

A novel actinobacterium, designated as strain WRP15-2T, was isolated from rhizosphere soil of rice plant (Oryza rufipogon). The strain was Gram-stain-positive, aerobic, and non-motile. Phylogenetic analysis based on the 16S rRNA gene sequences showed that strain WRP15-2T fell into the genus Saccharopolyspora. The strain shared the highest 16S rRNA gene sequence similarity with the type strains Saccharopolyspora kobensis JCM 9109T (99.1%), Saccharopolyspora indica VRC122T (98.9%), and Saccharopolyspora antimicrobica DSM 45119T (98.7%). However, the digital DNA-DNA hybridization and average nucleotide identity values among these strains confirmed that the microorganism represented a novel member of the genus Saccharopolyspora. Chemotaxonomic data revealed that strain WRP15-2T possessed MK-9(H4) as the predominant menaquinone. It contained meso-diaminopimelic acid as the diagnostic diaminopimelic acid and arabinose, galactose, and ribose as predominant whole-cell sugars. The detected phospholipids were dominated by phosphatidylethanolamine, hydroxy-phosphatidylethanolamine, phosphatidylmethylethanolamine, hydroxy-phosphatidylmethylethanolamine, and phosphatidylcholine. The predominant cellular fatty acids were iso-C16:0, C16:0, and iso-C15:0. The G + C content of the genomic DNA was 69.5%. Based on these genotypic and phenotypic data, it is supported that strain WRP15-2T represents a novel species of the genus Saccharopolyspora, for which the name Saccharopolyspora oryzae sp. nov. is proposed. The type strain is WRP15-2T ( = TBRC 15728T = NBRC 115560T).

Streptomyces macrolidinus sp. nov., a novel soil actinobacterium with potential anticancer and antimalarial activity

A novel actinomycete, strain RY43-2^T, belonging to the genus Streptomyces, was isolated from a peat swamp forest soil collected from Rayong Province, Thailand. The strain was characterized by using a polyphasic approach. The cell-wall peptidoglycan contained ll-diaminopimelic. Ribose and glucose were detected in its whole-cell hydrolysates. The strain contained anteiso-C_15:0, iso-C_14:0 and iso-C_16:0 as the predominant fatty acids, and MK-9(H₄), MK-9(H₆) and MK-9(H₈) as the major menaquinones. The phospholipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannoside, three unidentified ninhydrin-positive phospholipids and two unidentified phospholipids. Strain RY43-2^T showed the highest 16S rRNA gene similarity to Streptomyces misionensis JCM 4497^T (98.9 %) and Streptomyces lichenis LCR6-01^T (98.9 %). The draft genome of RY43-2^T was 6.7 Mb with 6078 coding sequences with an average G+C content of 70.8 mol%. Genomic analysis revealed that the average nucleotide identity (ANI) values based on blast (ANIb) and MUMmer (ANIm) between strain RY43-2^T and S. misionensis JCM 4497^T were 80.1 and 86.1%, respectively. The ANIb and ANIm values between strain RY43-2^T and S. lichenis LCR6-01^T were 77.0 and 85.5%, respectively. The digital DNA-DNA hybridization values were 25.2 and 23.0% in comparison with the draft genomes of S. misionensis JCM 4497^T and S. lichenis LCR6-01^T, respectively. The results of taxonomic analysis suggested that strain RY43-2^T represented a novel species of the genus Streptomyces for which the name Streptomyces macrolidinus sp. nov. is proposed. The type strain is RY43-2^T (=TBRC 7286^T=NBRC 115640^T). Strain RY43-2^T exhibited antimicrobial activity against Enterococcus faecium ATCC 51559, Colletotrichum capsici BMGC 106 and Colletotrichum gloeosporioides BMGC 107 with the minimum inhibitory concentration values of 25.0, 12.5, and 6.25 µg ml^-1. It also exhibited potent antimalarial activity against Plasmodium falciparum K1 with IC₅₀ of 0.0031 µg ml^-1. In addition, it showed cytotoxicity against Vero, KB, MCF-7 and NCI-H187 with IC₅₀ values of 0.0347, 6.15, 3.36 and 0.0352 µg ml^-1, respectively.

Nocardioides luti sp. nov., belonging to the family Nocardioidaceae isolated from kaolinite, exhibiting the biosynthesis potential of alkylresorcinol

A novel Gram-staining-positive, short rod-shaped, non-motile, and non-pigmented actinobacterial strain (KIGAM211^T) was isolated from kaolinite, a soft white clay mineral, collected from Sancheong in the Republic of Korea. On the basis of 16S rRNA gene sequence analysis, strain KIGAM211^T was determined to belong to the genus Nocardioides and was most closely related to N. ungokensis UKS-03^T (97.5% similarity). Cells could grow between 4 and 35 °C (optimum 30 °C), 0-3% (w/v) NaCl concentration (optimum 0%) and pH 5.5-8.5 (optimum 7.0) on R2A agar. Morphological appearance of colonies was cream-white, arranged singly or in groups. Biochemical characterization of strain KAGAM211^T indicated that it could hydrolyze casein, gelatin, Tweens 40 and tyrosine. Furthermore, the strain was positive for both oxidase and catalase activity. Strain KIGAM211^T was characterized chemotaxonomically by MK-8 (H₄) as the predominant menaquinone and phosphatidylglycerol (PG) and phosphatidylinositol (PI) as the major polar lipids. Major fatty acids were iso-C_16:0 and C_18:1 ω9c. The Ortholog average nucleotide identity (OrthoANI) and in silico DNA-DNA hybridization (isDDH) values between strain KIGAM211T and its most closely related strains of the Nocardioides genus were < 82% and < 24%, respectively, suggesting that strain KIGAM211^T represent a novel species. The whole genome size of KIGAM211^T was 4.52 Mb, comprising a total of 4,294 genes with DNA G + C content of 72.3 mol%. The genome of strain KIGAM211^T also comprises the biosynthetic gene cluster for alkylresorcinol as secondary metabolite. The results of physiological, taxonomical, phylogenetic, and whole genome analyses allowed for differentiation of strain KIGAM211^T from the recognized Nocardioides species. Therefore, strain KIGAM211^T is considered to represent a novel species, for which the name Nocardioides luti sp. nov. (type strain KIGAM211^T = KCTC 49364^T = JCM 33859^T) is proposed.

Recognition of DAP and activation of NF-κB by cytosolic sensor NOD1 in Oreochromis niloticus

As a lower vertebrate, the immune defense mechanism of fish mainly depends on the innate immune system. Nucleotide-binding oligomerization domain-like receptors (NLRs) are an important class of pattern recognition receptors in the innate immune system. In this study, NOD1 gene was cloned and characterized in Nile tilapia (Oreochromis niloticus). The ORF of Nile tilapia NOD1 gene was 2826 bp long and encoded 941 amino acid residues with a structure of CARD-NACHT-LRRs that was similar to the other counterparts in mammals and fishes. Phylogenetic and synteny analysis showed that NOD1 was conserved among different fishes and existed at least in the early stage of fish evolution. Expression pattern revealed that NOD1 mRNA was constitutively expressed in the tested tissues, while had high expression level in main immune organs and mucosal immune tissues (liver, head kidney, spleen, blood, gill, and intestine). Following Streptococcus agalactiae challenge, Nile tilapia NOD1 mRNA expression levels were altered in immune organs (liver, head kidney, spleen, blood), and the expression pattern was similar in liver, spleen and blood. Furthermore, the ligand recognition and signaling pathway of Nile tilapia NOD1 were also analyzed, it showed that NOD1 could recognize Tri-DAP intracellularly and activated NF-κB signaling pathway. In summary, our results indicated that the Nile tilapia NOD1 may play an important role in innate immune system and provided a basis for the functional study of NOD1 in teleost.

Functional Complementation Analysis (FCA): A Laboratory Exercise Designed and Implemented to Supplement the Teaching of Biochemical Pathways

Functional complementation assay (FCA) is an in vivo assay that is widely used to elucidate the function/role of genes/enzymes. This technique is very common in biochemistry, genetics and many other disciplines. A comprehensive overview of the technique to supplement the teaching of biochemical pathways pertaining to amino acids, peptidoglycan and the bacterial stringent response is reported in this manuscript. Two cDNAs from the model plant organism Arabidopsis thaliana that are involved in the metabolism of lysine (L,L-diaminopimelate aminotransferase (dapL) and tyrosine aminotransferase (tyrB) involved in the metabolism of tyrosine and phenylalanine are highlighted. In addition, the bacterial peptidoglycan anabolic pathway is highlighted through the analysis of the UDP-N-acetylmuramoyl-L-alanyl-D-glutamate-meso-2,6-diaminopimelate ligase (murE) gene from the bacterium Verrucomicrobium spinosum involved in the cross-linking of peptidoglycan. The bacterial stringent response is also reported through the analysis of the rsh (relA/spoT homolog) bifunctional gene responsible for a hyper-mucoid phenotype in the bacterium Novosphingobium sp. Four examples of FCA are presented. The video will focus on three of them, namely lysine, peptidoglycan and the stringent response.

Bacillus kyonggiensis sp. nov., isolated from soil of a lettuce field

A Gram-positive, rod-shaped, motile, endospore-forming bacterial strain, designated NB22(T), was isolated from soil of a lettuce field in Kyonggi province, South Korea, and was characterized by using a polyphasic taxonomic approach. This novel isolate grew optimally at 30-37°C and pH 8-9. It grew in the presence of 0-4% NaCl (optimum, 1-2%). Comparative 16S rRNA gene sequence analysis showed that strain NB22(T) was closely related to members of the genus Bacillus and fell within a coherent cluster comprising B. siralis 171544(T) (98.1%) and B. korlensis ZLC-26(T) (97.3%). The levels of 16S rRNA gene sequence similarity with respect to other Bacillus species with validly published names were less than 96.4%. Strain NB22(T) had a genomic DNA G+C content of 36.3 mol% and the predominant respiratory quinone was MK-7. The peptidoglycan contained meso-diaminopimelic acid. The major cellular fatty acids were iso-C(15:0), anteiso-C(15:0), C(14:0), and C(16:0). These chemotaxonomic results supported the affiliation of strain NB22(T) to the genus Bacillus, and the low DNA-DNA relatedness values and distinguishing phenotypic characteristics allowed genotypic and phenotypic differentiation of strain NB22(T) from recognized Bacillus species. On the basis of the evidence presented, strain NB22(T) is considered to represent a novel species of the genus Bacillus, for which the name Bacillus kyonggiensis sp. nov. is proposed. The type strain is NB22(T) (=KEMB 5401-267(T) =JCM 17569(T)).

Bacillus koreensis sp. nov., a spore-forming bacterium, isolated from the rhizosphere of willow roots in Korea

An endospore-forming, rod-shaped bacterium was isolated from the rhizosphere of willow roots in Korea. The bacterium, designated strain BR030T, was a strictly aerobic, motile rod. The cell wall contained type A1gamma peptidoglycan with meso-diaminopimelic acid as the diagnostic diamino acid. The major cellular fatty acids were anteiso-C(15 : 0), iso-C(15 : 0), iso-C(14 : 0) and iso-C(16 : 0). The major cellular phospholipids were phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine and unknown phospholipids (PL1, PL2). The genomic DNA G+C content was 36 mol%. Comparative 16S rRNA gene sequence analyses showed that strain BR030T formed a distinct phyletic line within the genus Bacillus and was most closely related to Bacillus flexus DSM 1320T, with 16S rRNA gene sequence similarity of 96.8 %. Sequence similarities to other type strains were lower than 96.2 %. On the basis of physiological and molecular properties, the isolate represents a novel species within the genus Bacillus, for which the name Bacillus koreensis sp. nov. is proposed. The type strain is BR030T (= KCTC 3914T = DSM 16467T).

Structural basis for peptidoglycan binding by peptidoglycan recognition proteins

Peptidoglycan (PGN) recognition proteins (PGRPs) are pattern-recognition receptors of the innate immune system that bind and, in some cases, hydrolyze bacterial PGNs. We determined the crystal structure, at 2.30-A resolution, of the C-terminal PGN-binding domain of human PGRP-Ialpha in complex with a muramyl tripeptide representing the core of lysine-type PGNs from Gram-positive bacteria. The peptide stem of the ligand is buried at the deep end of a long binding groove, with N-acetylmuramic acid situated in the middle of the groove, whose shallow end can accommodate a linked N-acetylglucosamine. Although most interactions are with the peptide, the glycan moiety also seems to be essential for specific recognition by PGRPs. Conservation of key PGN-contacting residues shows that all PGRPs employ this basic PGN-binding mode. The structure pinpoints variable residues that likely mediate discrimination between lysine- and diaminopimelic acid-type PGNs. We also propose a mechanism for PGN hydrolysis by Zn(2+)-containing PGRPs.

Actinoalloteichus cyanogriseus gen. nov., sp. nov

Phylogenetic analysis of 'Actinoalloteichus cyanogriseus' based on its 16S rDNA sequence confirmed that the organism belongs to the family Pseudonocardiaceae. It contains glutamic acid, alanine and meso-diaminopimelic acid as cell wall amino acids, and menaquinone 9 (H4). Its taxonomic characteristics differ from those of the previously described organisms of the family Pseudonocardiaceae. On the basis of these morphological, physiological, chemotaxonomic and phylogenetic analyses, a new genus, Actinoalloteichus, is proposed, along with a new species, namely Actinoalloteichus cyanogriseus sp. nov. The type strain is A. cyanogriseus IFO 14455T (= AS 4.1159T = JCM 6095T).

Ribonucleic acid in a "membrane" fraction of Escherichia coli and its relation to cell-wall synthesis

Suit, Joan C. (The University of Texas M. D. Anderson Hospital and Tumor Institute, Houston). Ribonucleic acid in a "membrane" fraction of Escherichia coli and its relation to cell-wall synthesis. J. Bacteriol. 84:1061-1070. 1962.-A small amount of ribonucleic acid (RNA) was found in a "membrane" fraction prepared from osmotically sensitized Escherichia coli. It exhibited an elevated metabolic activity in that it attained the highest specific activity of any RNA in subcellular fractions of logarithmic-phase cells or spheroplasts prepared from logarithmic-phase cells which had been allowed to incorporate P(32) briefly. The metabolic activity of this RNA, in terms of P(32) incorporation, was found to be independent of cell-wall synthesis in the diaminopimelic acid (DAP)-less mutant, E. coli W 173-25, but was inhibited by penicillin in both this strain and in E. coli B. The latter effect is considered to be a result of other complex inhibitions of cellular metabolism by the antibiotic. The development of sensitivity to osmotic shock, capability of recovery, and synthesis of macromolecules in penicillin-treated and DAP-starved cultures, under these conditions, is described.

Production of L-threonine by auxotrophic mutants of Escherichia coli

Two auxotrophic mutants of Escherichia coli have been shown to accumulate significant amounts of l-threonine in the culture medium. One mutant, 13071, is deficient in alpha,epsilon-diaminopimelic acid (DAP), and the other, 13070, is deficient in both DAP and methionine. Accumulation of l-threonine by 13071 in a synthetic medium with mannitol as the carbon source at 37 C incubation temperature was greatly influenced by initial DAP concentration. At an optimal level of DAP a yield of 1.5 g/liter l-threonine was obtained in 28 hr. l-Threonine accumulation by 13070 with sorbitol as the carbon source at 28 C incubation temperature was dependent upon the initial concentration of both DAP and methionine. At optimal levels of the two deficient amino acids, a yield of 2.0 g/liter l-threonine was obtained in 44 to 48 hr. By adding to the medium suitable quantities of beet molasses or sucrose supplemented with corn steep liquor the yield could be raised to almost 4 g/liter.l-Threonine of extremely high purity was isolated from fermentation broth from both mutants. The product was not contaminated with any detectable amounts of d-threonine or allothreonine.

RAPID DIFFERENTIATION BETWEEN NOCARDIA AND STREPTOMYCES BY PAPER CHROMATOGRAPHY OF WHOLE-CELL HYDROLYSATES

Whole-cell hydrolysates were prepared from 58 strains of nocardiae and streptomycetes. Strains morphologically intermediate between the two genera and morphological variants of the same strains were included. Paper chromatograms made from the whole-cell hydrolysates clearly demonstrated meso-diaminopimelic acid as a major constituent of cultures of Nocardia spp., and LL-diaminopimelic acid as a major constituent of cultures of Streptomyces spp. In cultures of ten strains of N. madurae and of three of N. pelletieri, meso-diaminopimelic acid predominated, thereby supporting the assignment of these species to the genus Nocardia.

CHEMICAL COMPOSITION OF CELL-WALL PREPARATIONS FROM STRAINS OF VARIOUS FORM-GENERA OF AEROBIC ACTINOMYCETES

Cell-wall preparations were made from more than 140 strains of aerobic actinomycetes representing most of the form-genera that have been proposed. All cell-wall preparations contained as major constituents glucosamine, muramic acid, alanine, and glutamic acid. In addition, cell-wall preparations from various types of streptomycetes and strains of Microëllobosporia contained glycine and ll-alpha,epsilon-diaminopimelic acid; those from strains of most Actinoplanaceae and micromonosporae contained glycine and meso-alpha-epsilon-diaminopimelic acid; those from strains of Thermoactinomyces, Microbispora, Dermatophilus, and nocardiae of the madurae-pelletieri group contained meso-alpha,epsilon-diaminopimelic acid; and those from strains of Thermomonospora, Micropolyspora, and most nocardiae contained meso-alpha,epsilon-diaminopimelic acid, arabinose, and galactose. All the strains used were also studied morphologically.

Substrate specificity of Escherichia coli LD-carboxypeptidase on biosynthetically modified muropeptides

Escherichia coli murein can be biosynthetically modified. Amino acids at positions 3 and 4 (m-diaminopimelic acid and D-alanine, respectively) on the peptide moieties can be changed under appropriate growth conditions. The activity of E. coli LD-carboxypeptidase on biosynthetically modified substrates has been studied in vitro. The enzyme hydrolysed all tested disaccharide-tetrapeptide monomeric muropeptides modified at position 4. Monomers with m-lanthionine, but not with L-ornithine, instead of m-diaminopimelic acid at position 3 were accepted. However, neither cross-linked muropeptides nor macromolecular murein were substrates for the reaction. Our observations argue against a direct effect of LD-carboxypeptidase on macromolecular murein metabolism.

Compositional analysis of peptidoglycan by high-performance anion-exchange chromatography

A high-performance anion-exchange chromatography method with pulsed-amperometric detection has been developed for the simultaneous analysis of both amino acids and amino sugars and applied to the compositional analysis of peptidoglycan hydrolysates. Chromatography of the acid hydrolysis products was performed on a CarboPac PA-1 anion-exchange column, with pulsed-amperometric detection. Complete resolution of the two amino sugars (glucosamine and muramic acid) and eight of the nine amino acids (Ala, diaminobutyric acid, diaminopimelic acid, Glu, Gly, homoserine, Lys, Orn, and Ser) known to occur in various peptidoglycans was achieved within 70 min. Only homoserine and glycine (retention times 26.8 and 26.9 min, respectively) were not resolved by this procedure, but the simultaneous occurrence of these two amino acids in peptidoglycan is extremely rare. Reproducibility of the separations was shown to be very high and detection limits exceeded 10 pmol for glucosamine. This convenient and simple analysis was applied to the quantitation of many crude peptidoglycan samples isolated from the species of the Proteeae (Proteus, Providencia, and Morganella) for the determination of the extent of peptidoglycan O-acetylation.

Stability of a host-vector system based on complementation of an essential gene in Escherichia coli

Antibiotic selection is the most common selection system for plasmid-containing bacteria. This technique, nevertheless, can be a source of problems during the expression of heterologous genes in Escherichia coli. We have developed an alternative selection system based on the complementation of a chromosomal auxotrophic (dapD2) mutation by the corresponding wild type gene carried on a plasmid. We show that the system effectively selects for the presence of plasmid on solid and liquid medium. In addition, we have observed a loss of viability associated with high levels of gene expression and accumulation of a heterologous protein, but the selective power and improved intrinsic stability of the dap+ plasmid, compared to a beta-lactamase (bla) based vector, excludes overgrowth of the culture by plasmidless cells.

The use of multiple mass spectral line pairs for enhanced precision in isotope enrichment studies of 15N-labeled amino acids

A method for enhancing the precision in the calculation of isotope enrichment for 15N-labeled amino acids is presented. The method utilizes multiple line pairs for the calculation of isotope enrichment. Using multiple line pairs allows the evaluation of calibration curves for nonlinear behavior and permits differentiation among sites containing more than one labeled nitrogen. The increase in precision is related to the number of isotopically shifted line pairs used in calculating the isotopic enrichment and varies with the amino acid of interest.

Structural modification of Escherichia coli peptidoglycan induced by bicyclomycin

We have studied the modification of Escherichia coli peptidoglycan induced by bicyclomycin. For this purpose liquid chromatography for peptidoglycan analysis has been used. The main alteration found was an increase of diaminopimelyl-diaminopimelyl bridge containing subunits. Our results show that bicyclomycin impairs the normal breakage of that interpeptidic bond, whose cleavage is needed for the normal remodeling of peptidoglycan and cell growth. Based on the analysis of the possible structure of diaminopimelyl-diaminopimelyl bond and bicyclomycin, we propose a hypothesis on the mechanism of action of bicyclomycin.

Bacteriolytic factor in the salivary glands of Aedes aegypti

Salivary gland homogenates from adult Aedes aegypti lyse Micrococcus lysodeikticus cells. The bacteriolytic factor is present in a cell type common to both male and female mosquitoes, as well as in the crop of sugar-feeding mosquitoes. The bacteriolytic factor releases digestion products from sacculi of Escherichia coli that are different from those of hen egg white lysozyme.

[Characterisation of a new endopeptidase from sporulating Bacillus sphaericus which is specific for the gamma-D-glutamyl-L-lysine and gamma-D-glutamyl-(L)meso-diaminopimelate linkages of peptidoglycan substrates (author's transl)]

A new peptidase which splits substrates related to the peptidic chains of peptidoglycans was found in the cell cytoplasm of sporulating Bacillus sphaericus. This is a gamma-D-glutamyl-L-diaminoacid endopeptidase (endopeptidase II). It was shown to have substrate requirements different from those of the previously described gamma-D-glutamyl-(L)meso-diaminopimelate endopeptidase (endopeptidase I). The substrates for endopeptidase II are peptides of the general type: formula: (see text). Unsubstituted N-terminal L-alanine was a strict requirement for endopeptidase II activity. Specific activities were variable with the nature and the substitution of the diaminoacid C-terminal groups. The role of endopeptidase II in the biosynthesis of the spore cortex is discussed.

Meso-alpha,epsilon-diaminopimelate D-dehydrogenase: distribution and the reaction product

A high activity of meso-alpha-epsilon-diaminopimelate dehydrogenase was found in extracts of Bacillus sphaericus, Brevibacterium sp., Corynebacterium glutamicum, and Proteus vulgaris among bacteria tested. B. sphaericus IFO 3525, in which the enzyme is most abundant, was chosen to study the enzyme reaction. The enzyme was not induced by the addition of meso-alpha-epsilon-diaminopimelate to the growth medium. The reaction product was isolated and identified as alpha-amino-epsilon-ketopimelate by a comparison of the properties of its 2,4-dinitrophenylhydrazone with those of an authentic sample in silica gel thin-layer chromatography, absorption, infrared and proton nuclear magnetic resonance spectrometry, and elemental analyses. The alpha-amino-epsilon-ketopimelate formed enzymatically was decarboxylated by H2O2 to yield L-alpha-aminoadipate. This suggests that the amino group with D-configuration in the substrate is oxidatively deaminated; the enzyme is a D-amino acid dehydrogenase. L-alpha-Amino-epsilon-ketopimelate undergoes spontaneous dehydration to the cyclic delta1-piperideine-2,6-dicarboxylate. The enzyme reaction is reversible, and meso-alpha-epsilon-diaminopimelate was formed in the reductive amination of L-alpha-epsilon-ketopimelate.

[Chemotaxonomic markers of several coryneform bacteria and the "Rhodochrous" group]

Chemotaxonomic characters (the monosaccharide composition and diaminopimelic acid (DAP) of cell hydrolysates, the type of lipid LCN-A) were studied with bacteria of the "rhodochrous" complex and the Arthrobacter genus isolated from natural substrates as well as with collection strains of the genera Arthrobacter, Brevibacterium and Corynebacterium. If arabinose, galactose and meso-DAP were present in cell hydrolysates of these bacteria, they always contained lipid LCN-A. Bacteria of the "rhodochrous" complex can be differentiated from Corynebacterium sensu stricto by location of lipid LCN-A spots on chromatograms, and from the genera Brevibacterium (B. linens) and Arthrobacter, by the presence of arabinose, meso-DAP and lipid LCN-A in the cells. The representatives of two latter genera do not contain arabinose and lipid LCN-A in their cells.

[Characterization and separation of exocellular gamma-D-glutamyl-(L)meso-diaminopimelate endopeptidase and LD-carboxypeptidase from Bacillus sphaericus 9602]

Two exocellular enzymes have been characterized in the culture media of sporulating Bacillus sphaericus 9602 : a gamma-D-glutamyl-(L) meso-diaminopimelate endopeptidase and a L-lysyl-D-alanine carboxypeptidase. These two enzymes and the corresponding membrane-bound peptidases found in Bacillus sphaericus and Bacillus subtilis strains have similar activities. Their separation is described. Both enzymes were precipitated between 25 and 65 per cent (NH4)2SO4 saturation and a first chromatography was carried out on a column of DEAE-cellulose. The separation was performed by chromatography on hydroxyapatite, each enzyme was finally filtered through Ultrogel AcA 34. After separation, the endopeptidase activity and the carboxypeptidase activity increased respectively 93 and 11 fold. Both enzymes have a molecular weight near 200 000. By gel electrophoresis at pH 8.5, they were shown to have different mobilities : the carboxypeptidase is more anionic than the endopeptidase.

[Enzymatic preparation of peptides of the general type: L-Ala-D-Glu-L-mesodiaminopimelyl (L)-D (140) Ala by transfer reactions between non radioactive corresponding peptides and D-alanine (140)]

Membrane bound LD-transpeptidase of Streptococcus faecalis ATCC 9790 was used to catalyse transpeptidation reactions between non radioactive peptide donors of the general type: L-Ala-D-Glu (L)meso-A2pm(L)-D-Ala and D-(14C) alanine acceptor. The presence of one or two amide residues on the carboxyl groups of glutamic acid and meso-diaminopimelic acid increases the transfer reactions and subsequently the yield in radioactive peptides L-Ala-D-Glu (L)meso-A2pm(L)-D-(14C) Ala.

Isolation and purification of D-alanyl-meso-2, 6-diaminopimelic acid endopeptidase of Streptomyces L-3 enzyme using soluble substrates of known chemical structure from Lactobacillus plantarum cell wall digests

D-alanyl-meso-2, 6-diaminopimelic acid (D-Alanyl-meso-A2pm) endopeptidase was isolated and purified from a crude Streptomyces L-3 enzyme preparation by ion exchange chromatography and isoelectric focusing in a density gradient. During its purification, its hydrolytic activity was assayed on cell walls of Lactobacillus plantarum ATCC 8014 and soluble glycopeptides and peptides, of known chemical structures, prepared enzymatically from these cell walls. A fraction with an isoelectric point of pH 7.9 cleaved the bond between the carboxyl group of the D-alanine residue at the C-terminal in one peptide subunit and one of the two amino groups of the A2pm residue in the neighboring peptide subunit. Unlike the crude enzyme, the endopeptidase in this fraction showed no N-acetylmuramyl-L-alanine amidase, A2pm carboxyamide amidase or proteinase(s) activity and it was immunologically homogeneous.

Electron microscope studies of conditional spore cortexless mutants of Bacillus sphaericus

Spore cortex of conditional cortexless mutants of Bacillus sphaericus 9602 was not detectable by electron microscopy unless the medium was supplemented with meso-alpha,epsilon-diaminopimelic acid during sporulation. Other spore structures appeared normal. Spore shape was quite irregular in the absence of meso-alpha,epsilon-diaminopimelic acid.

Peptidoglycan synthesis in L-phase variants of Bacillus licheniformis and Bacillus subtilis

Stable L-phase variants isolated from Bacillus licheniformis and Bacillus subtilis, when grown in osmotically stabilized media, do not synthesize peptidoglycan but have been found to accumulate the nucleotide precursors of this polymer. The enzymes involved in the synthesis of these precursors and the later membrane-bound stages of peptidoglycan synthesis have been investigated, and the L-phase variants have been shown to contain lesions, which provide a rational explanation for the absence of peptidoglycan and for the nature of the precursor accumulated. The majority of the L-phase variants contained a single enzymic defect, but two strains were isolated with double lesions. Five out of seven strains examined accumulated uridine 5'-diphosphate (UDP)-MurAc-L-ala-D-glu and were unable to synthesize diaminopimelic acid as a consequence of a defect in aspartate-beta-semialdehyde dehydrogenase activity. Two strains were deficient in UDP-MurAc: L-alanine ligase and accumulated UDP-MurAc. One strain accumulated the complete nucleotide precursor UDP-MurAc-L-ala-D-glu-mA2pm-D-ala-D-ala and was deficient in phospho-N-acetylmuramyl pentapeptide translocase. A second strain also had this lesion, together with defective aspartate-beta-semialdehyde dehydrogenase activity. The other enzymes of peptidoglycan synthesis were present in the L-phase variants, with activities similar to those found in the parent bacilli grown under identical conditions. Membrane preparations from certain of the L-phase variants were also capable of synthesizing the secondary polymers poly(glycerol phosphate) teichoic acid and teichuronic acid and also a polymer of N-acetylglucosamine.

REVERSION OF L FORMS AND SPHEROPLASTS OF PROTEUS MIRABILIS

Altenbern, Robert A. (U.S. Army Chemical Corps, Fort Detrick, Frederick, Md.). Reversion of L forms and spheroplasts of Proteus mirabilis . J. Bacteriol. 85: 269–272. 1963.—Spheroplasts or 3-B type L forms of Proteus mirabilis formed by growth in the presence of penicillin are able to revert to the bacillary form, as judged by regain of resistance to osmotic shock. Reversion takes place in the absence of exogenous nutrients, although at a lesser rate than that observed in a nitrogen-rich medium. Either chloramphenicol or 6-azauracil can completely inhibit reversion of spheroplasts in a penicillin-free medium. By direct measurement, there was no detectable change in total protein content throughout the period of reversion of a spheroplast suspension. Assay for acid-insoluble diaminopimelic acid (DAP) revealed that a large part of the DAP of the cell wall of normal cells was lost when the cells were converted to spheroplasts by exposure to penicillin. Upon transfer to penicillin-free medium, there was a rapid increase in acid-insoluble DAP in the wall of the reverting spheroplast. When spheroplasts were transferred to penicillin-free medium containing chloramphenicol, the acid-insoluble DAP in the wall of the spheroplast continued to decrease. The significance of these results in regard to sites of activity of the antibiotics involved is discussed.