Gamma-ray thermoluminescence measurements: a record of fallout deposition in Hiroshima?

In certain Hiroshima neighborhoods, radiation measurements using thermoluminescence dosimetry (TLD) exceed what can be explained by the initial gamma-ray doses and uncertainties from the Dosimetry System 2002 (DS02). This problem was not previously recognized as being isolated to certain parts of that city. The ratio between TLD measurements and DS02 dose calculations for gamma rays appear to grow larger than unity up to more than three with increasing ground range, but closer examination shows the excess TLD dose (0.1, 0.2, or possibly up to 0.8 Gray) is correlated with certain neighborhoods and could be due to radioactive fallout. At Nagasaki, the TLD measurements do not show this same excess, probably because there were no TLD measurements taken more than 800 m downwind (eastward) from the Nagasaki hypocenter, so that any small excess TLD dose was masked by larger initial gamma-ray doses of 25–80 Gray in the few downwind samples. The DS02 Report had noted many measurements lower than the DS02 calculation for several Nagasaki TLD samples, independent of ground range. This was explained as being the result of previously unaccounted urban shielding which was observed from Nagasaki pre-bomb aerial photos. However, the Hiroshima excess TLD dose issue was not resolved. If the excess TLD doses at Hiroshima are an indication of fallout, it may be possible to use additional TLD studies to make better estimates of the locations and radiation doses to survivors from the fallout after the bombings at both cities.     

Microbial transformation of α-pinene

Summary A bacterium capable of utilizing -pinene as a sole carbon and energy source was isolated from soil. This strain, named strain S201-1, which was identified as Pseudomonas maltophilia on the basis of its taxonomical properties, accumulated limonene, borneol, camphor, perillic acid, and 2-(4-methyl-3-cyclohexenylidene) propionic acid from -pinene in the culture broth. It was demonstrated that -pinene, -pinene, borneol, camphor, and a number of p-menthane derivatives were oxidized by this strain. Relations between the protonation of -pinene and the formation of the products by the microbe are discussed.     

Microbial Fossils in the 2.63 Ga Jeerinah Formation,Western Australia—Evidence of Microbial Oxidation

A diamond drill core from the upper part of the Jeerinah Formation (～2.63 Ga), underlying the Hamersley Group, deposited at a time when the oxygen concentrations in the marine environment were extremely low, was examined for microbial fossils. The paper presents organo-mineral structures in the form of twisted stalks produced by bacteria being present in the laminated black carbonaceous shale sediments. These twisted stalks are organo-mineral structures produced by microaerophilic Fe(II)-oxidizing-type bacteria such as Gallionella and/or Mariprofundus that are active at very low-oxygen concentrations, thus providing evidence for oxygen being present in the marine environment at 2.63 Ga.     

Microbial Degradation of α-Picolinic Acid, 2-Pyridinecarboxylic Acid

The biological effects of raw winged bean seeds were investigated with feeding experiments on rats, and the effects of lectin (phytohemagglutinin) present in the seeds are discussed. Administration of a 30% raw winged bean diet caused strong growth depression in young rats, and led to death within 10 ~ 20 days, inducing severe damage to the small intestine of the rats. Significant morphological changes of the intestinal mucosa were observed with a microscopic investigation. As the lethal effect was eliminated by autoclaving but not removed with supplementation of 0.5% l-methionine to the raw winged bean diet, the lectin was assumed to be closely related to the deleterious effects of raw winged bean. In vitro and in vivo digestion tests of the lectin revealed that the winged bean lectin had resistance to peptic, pancreatic and membrane digestions. The hemagglutinating activity was also detected in the intestinal mucosa and faeces from rats ingesting the raw winged bean or its purified lectin. The binding action of lection to mucosal epitheliums of the gastrointestinal tract is suggested to be the initial step of the deleterious effects induced by the winged bean lectin.     

Microbial 1β-Hydroxylation of Digitoxigenin

l-Deoxy-l-l-proIino-d-fructose was isolated from flue-cured tobacco leaves in crystalline form. The structure was confirmed by comparison with synthetic compound.     

Microbial acid-stable α-amylases: Characteristics,genetic engineering and applications

Among the wide variety of amylolytic enzymes synthesized by microorganisms, α-amylases are the most widely used biocatalysts in starch saccharification, baking industries and textile desizing. These enzymes randomly cleave the α-1,4-glycosidic linkages in starch, generating maltose and malto-oligosaccharides. The commercially available α-amylases have certain limitations, such as limited activity at low pH and Ca²⁺-dependence, and therefore, the search for novel acid-stable and thermostable amylases from extremophilic microorganisms and the engineering of the already available enzymes have been the major areas of research in this field over the years. Several attempts have been made to find suitable microbial sources of acid-stable and thermostable α-amylases. Acid-stable α-amylases have been reported in fungi, bacteria and archaea. α-Amylases that are active at elevated temperatures have been reported in bacteria as well as in archaea. α-Amylases that possess both characteristics, to the extent required for their various applications are very scarce. The developments that have been made in molecular biology, directed evolution and structural conformation studies of α-amylases for improving their properties to suit various industrial applications are discussed in this review.     

Microbial production of poly-γ-glutamic acid

Poly-γ-glutamic acid (γ-PGA) is a natural, biodegradable and water-soluble biopolymer of glutamic acid. This review is focused on nonrecombinant microbial production of γ-PGA via fermentation processes. In view of its commercial importance, the emphasis is on l-glutamic acid independent producers (i.e. microorganisms that do not require feeding with the relatively expensive amino acid l-glutamic acid to produce γ-PGA), but glutamic acid dependent production is discussed for comparison. Strategies for improving production, reducing costs and using renewable feedstocks are discussed.     

Microbial genomics: tropical treasure?

A Brazilian consortium has unveiled the genomic DNA sequence of the purple-pigmented bacterium Chromobacterium violaceum, a dominant component of the tropical soil microbiota. The sequence provides insight into the abundant potential of this organism for biotechnological and pharmaceutical applications.     

Microbial conversion of steroids III: 11α-hydroxylation by fungal mycelium

Summary A mutant of Aspergillus ochraceus has been developed, which converts progesterone (substrate concentration 40 g/l) to 11-hydroxyprogesterone in high yields (90%). The formation of 6, 11-dihydroxy compound is minimal at high substrate concentrations. The bioconversion rate is also much higher. The various parameters for optimal conversion have been standardised.     

Microbial metabolism of monoterpenes — recent developments

Monoterpenes are important renewable resources for the perfume and flavour industry but the pathways and enzymology of their degradation by microorganisms are not well documented. Until recently the acyclic monoterpene alcohols, (+)-camphor and the isomers of limonene were the only compounds for which significant sections of catabolic pathways and associated enzymology had been reported. In this paper recent developments in our understanding of the enzymology of ring cleavage by microorganisms capable of growth with 1,8-cineole and -pinene are described. 1,8-Cineole has the carbocyclic skeleton of a monocyclic monoterpene with the added complication of an internal ether linkage. Ring hydroxylation strategy and biological Baeyer-Villiger oxygenation lead to an efficient method for cleaving the ether linkage. -Pinene is an unsaturated bicyclic monoterpene hydrocarbon. At least two catabolic pathways exist. Information concerning one of them, in which -pinene may be initially converted into limonene, is rudimentary. The other involves attack at the double bond resulting in formation of -pinene epoxide. Ring cleavage is then catalysed by a novel lyase that requires no additional components and breaks both carbocyclic rings in a concerted manner.     

Microbial Formation of D-Pantothenic Acid-α-glucoside

The formation of D-pantothenic acid-α-glucoside (PaA-α-G) was found from D-pantothenic acid (PaA) and maltose in incubation mixtures of microorganisms, especially Saccharomyces yeasts and Sporobolomyces coralliformis IFO 1032. The reaction conditions were investigated for formation of PaA-α-G by resting cells of Spor. coralliformis. The formation of the compound increased with PaA concentration (3~20 mg/ml). The yield was maximum at 5~10 mg/ml of PaA. Cetyl trimethyl ammonium bromide (0.1 %) promoted the formation of PaA-α-G. Sucrose was the optimal α-glucosyl donor. When 30 mg/ml of sucrose was fed to the reaction mixture (initial sucrose, 100 mg/ml; and PaA, 10 mg/ml) at 12-hr intervals, 5.74 mg/ml (3.30 mg/ml as PaA) of PaA-α-G was formed in 48-hr incubation at 28°C with shaking. PaA-α-G was also formed by yeast α-glucosidase, mold maltase and the cell-free extract of Spor. coralliformis. The compound showed approximately 9~10% and 0.1~0.3% (molar ratio) of activity of PaA for Saccharomyces carlsbergensis ATCC 9080 and Lactobacillus plantarum ATCC 8014, respectively. The compound had the same microbiological activity as authentic 4′-O-(α-D-glucopyranosyl)-D-pantothenic acid.     

Archaeal Microbial Diversity of Hypersaline Lake Acıgöl,Denizli, Turkey

Archaeal diversity in Lake Ac?göl, a closed-basin, alkaline, hypersaline lake located at the northern edge of western Tourides in southwest Anatolia, was investigated using culture-independent methods. Microbial mat samples were collected from six different points. Archaeal 16S rRNA gene libraries were generated using domain specific oligonucleotide primers, and 16S rRNA gene sequences of clone libraries were analyzed phylogenetically. Denaturing gradient gel electrophoresis of 16S rRNA genes showed a variance in diversity with spatial differences. Archaeal diversity of Ac?göl is dominated by the members of family Halobacteriaceae which requires both high salt concentration and high pH for growth. Sequence analysis of archaeal 16s rRNA genes indicates the presence of the phylotypes affiliated with the genera Halorubrum, Halosimplex, Halorhabdus, Haloterrigena and Natronococcus in the analyzed samples.     

One-pot Microbial Synthesis of 2′-deoxyribonucleoside from Glucose, Acetaldehyde, and a Nucleobase

A one-pot enzymatic synthesis of 2′-deoxyribonucleoside from glucose, acetaldehyde, and a nucleobase was established. Glycolysis by baker’s yeast (Saccharomyces cerevisiae) generated ATP which was used to produce d-glyceraldehyde 3-phosphate production from glucose via fructose 1,6-diphosphate. The d-glyceraldehyde 3-phosphate produced was transformed to 2′-deoxyribonucleoside via 2-deoxyribose 5-phosphate and then 2-deoxyribose 1-phosphate in the presence of acetaldehyde and a nucleobase by deoxyriboaldolase, phosphopentomutase expressed in Escherichia coli, and a commercial nucleoside phosphorylase. About 33 mM 2′-deoxyinosine was produced from 600 mM glucose, 333 mM acetaldehyde and 100 mM adenine in 24 h. 2′-Deoxyinosine was produced from adenine due to the adenosine deaminase activity of E. coli transformants.     

Microbial diversity of soils on the banks of the Solimões and Negro rivers, state of Amazonas, Brazil

Analysis of bacterial diversity in soils along the banks of the Solimões and Negro rivers, state of Amazonas, Brazil, was by partial sequencing of the genes codifying the rDNA16S region. Diversity of operational taxonomic units (OTU) and of the divergent sequences obtained were applied in comparative analysis of microbiological diversity in the two environments, based on richness estimators and OTU diversity indices. The higher OTU diversity in the Solimões was based on the higher number of parameters that evoke this. The interaction between the nucleotide sequences of bacteria inhabiting the two riverine environments indicated that the two microrganism communities are similar in composition.