J. Corman

Bio: J. Corman is an academic researcher from United States Department of Agriculture. The author has contributed to research in topics: Serratia marcescens & Serratia. The author has an hindex of 6, co-authored 9 publications receiving 340 citations.

The effect of certain cultural factors on production of dextransucrase by Leuconostoc mesenteroides.

Abstract: Present knowledge on the characteristics of dextransucrase and its mode of action is based primarily on the important investigations of Hehre (1941, 1946, 1951) and Hehre and Sugg (1942). Hitherto, a serious impediment to studies of this interesting enzyme has been the difficulty of procuring dextransucrase. Development of further knowledge about it would be greatly facilitated by the availability of culture liquors rich in dextransucrase. The rapid formation of dextransucrase in high yields has been reported in a preliminary note (Koepsell and Tsuchiya, 1952). The present report deals in greater detail with our observations on factors affecting production of dextransucrase from Leuconostoc mesenteroides, strain NRRL B-512.2 However, culture liquors high in activity have been obtained from a large number of the organisms tested. The dextran produced by strain NRRL B-512 in the conventional whole culture procedure contains about 95 per cent a-1,6-glucopyranosidic linkage. Although the non-1,6 linkages have been assumed to be of the a-1,4 type, definite proof on this point is lacking (Jeanes and Wilham, 1950). L. mesenteroides, strain NRRL B-512, or its substrains, is the organism principally used in investigations of clinical dextran in the United States. Although the term \"dextransucrase\" is used in the singular for convenience, the possibility that more than one enzyme may be involved in the synthesis of dextran is recognized.

Preservation of microorganisms by freeze-drying. I. Cell supernatant, Naylor-Smith solution, and salts of various acids as stabilizers for Serratia marcescens.

Abstract: Inasmuch as all living things usually require a high content of water either internally or externally, or both, it is remarkable that microorganisms, especially spore forms, can sometimes withstand an extreme desiccating environment. Any success achieved by chemical or physical means in modifying viability, that is in hastening or preventing death of the desiccated cell, has implications in many different fields. The various techniques exploited during the last 45 years in the preservation of bacteria by drying have been reviewed in an interesting and very useful manner by Fry (1954). Although he commends Naylor and Smith (1946) on the logical development of their stabilizing medium for the freezedrying of Serratia marcescens, he points out that its general applicability would have to be tested with more sensitive organisms. The present study of preservation by drying is also limited to S. marcescens but a considerable variety of new substances has been tried besides the Naylor-Smith components. Some of our results should find application in the preservation of other organisms freeze-dried under similar conditions. Experiments with sensitive strains of yeast and bacteria will be reported in a later paper.

Growth Promotion of Plants Inoculated with Phosphate-Solubilizing Fungi

Abstract: Phosphorus is an important plant nutrient which is in short supply in many agricultural soils Because much of the soluble phosphate (P) applied to soils as fertilizer is “fixed” by the soil and rendered less available to plants, the long-term application of P fertilizers has resulted in an accumulation of total soil P, most of which is poorly soluble Many soil fungi, predominantly of the genera Aspergillus and Penicillium , have been shown to possess the ability to solubilize sparingly soluble phosphates in vitro by secreting inorganic or organic acids Growth promotion and increased uptake of P by plants inoculated with P-solubilizing fungi have also been reported by many investigators

Structure-Function Relationships of Glucansucrase and Fructansucrase Enzymes from Lactic Acid Bacteria

Abstract: Lactic acid bacteria (LAB) employ sucrase-type enzymes to convert sucrose into homopolysaccharides consisting of either glucosyl units (glucans) or fructosyl units (fructans). The enzymes involved are labeled glucansucrases (GS) and fructansucrases (FS), respectively. The available molecular, biochemical, and structural information on sucrase genes and enzymes from various LAB and their fructan and a-glucan products is reviewed. The GS and FS enzymes are both glycoside hydrolase enzymes that act on the same substrate (sucrose) and catalyze (retaining) transglycosylation reactions that result in polysacchande formation, but they possess completely different protein structures. GS enzymes (family GH70) are large multidomain proteins that occur exclusively in LAB. Their catalytic domain displays clear secondary-structure similarity with α-amylase enzymes (family GH13), with a predicted permuted (β/α)8 barrel structure for which detailed structural and mechanistic information is available. Emphasis now is on identification of residues and regions important for GS enzyme activity and product specificity (synthesis of α-glucans differing in glycosidic linkage type, degree and type of branching, glucan molecular mass, and solubility). FS enzymes (family GH68) occur in both gram-negative and gram-positive bacteria and synthesize β-fructan polymers with either β-(2→6) (inulin) or β-(2→1) (levan) glycosidic bonds. Recently, the first high-resolution three-dimensional structures have become available for FS (levansucrase) proteins, revealing a rare five-bladed β-propeller structure with a deep, negatively charged central pocket. Although these structures have provided detailed mechanistic insights, the structural features in FS enzymes dictating the synthesis of either β-(2→6) or β-(2→1) linkages, degree and type of branching, and fructan molecular mass remain to be identified. Copyright © 2006, American Society for Microbiology. All Rights Reserved.

Physicochemical Factors in Growth

Abstract: Some physicochemical factors affecting microbial growth are controlled by the constituents of the culture medium (hydrogen ion activity, water activity, osmotic pressure, and viscosity). Others are controlled by the external environment (temperature, oxygen, light, hydrostatic pressure, and magnetic-field strength). This chapter addresses practical aspects of application and control of physicochemical factors. Continuous pH control may be achieved by the automatic addition of acid or base. The effects of hydrostatic pressure on the physiology and metabolism of bacteria are discussed. A number of Pseudomonas and Bacillus species also exhibit a microaerophilic phenotype when growing in low-substrate media. The oxidation-reduction (redox) potential (Eh ) provides a useful scale for measuring the degree of anaerobiosis. Some motile bacteria that possess magnetite- or greigite containing magnetosomes, e.g., Magnetospirillum (formerly Aquaspirillum) magnetotacticum, align with the Earth geomagnetic field, which has strength of about 1 G. As a consequence, they show a biased swimming behavior, and both north-seeking and south-seeking forms are known. This behavior has been termed magnetotaxis and is thought, in part, to help these bacteria (many of which are microaerophilic) orient toward aquatic sediments where dissolved-oxygen concentrations are lower than in surface waters.

Leuconostoc dextransucrase and dextran: production, properties and applications

Abstract: This review covers the production, properties and applications of the biopolysaccharide dextran; this biopolymer can be produced via fermentation either with Leuconostoc mesenteroides strains and other lactic acid bacteria or with certain Gluconobacter oxydans strains. The former strains convert sucrose into dextran with the dextransucrase enzyme whereas the latter convert maltodextrins into dextran with the dextran dextrinase enzyme. Emphasis is mainly focused on Leuconostoc strains as producer organisms of dextransucrase and dextran types. In addition to industrial fermentation processes producing the enzymes and/or the dextrans, biocatalysis principles are also being developed, whereby enzyme preparations convert sucrose or maltodextrins, respectively, into (oligo)dextrans. The chemical and physical properties of different dextrans are discussed in detail, together with the characteristics and molecular mode of action of dextransucrase. Subsequently, useful applications of dextran and some problems associated with undesirable formation of dextran are outlined. Copyright © 2005 Society of Chemical Industry

Production of citric and oxalic acids and solubilization of calcium phosphate by penicillium bilaii

Abstract: An isolate of Penicillium bilaii previously reported to solubilize mineral phosphates and enhance plant uptake of phosphate was studied. Using agar media with calcium phosphate and the pH indicator alizarin red S, the influence of the medium composition on phosphate solubility and medium acidification was recorded. The major acidic metabolites produced by P. bilaii in a sucrose nitrate liquid medium were found to be oxalic acid and citric acid. Citric acid production was promoted under nitrogen-limited conditions, while oxalic acid production was promoted under carbon-limited conditions. Citric acid was produced in both growth and stationary phases, but oxalic acid production occurred only in stationary phase. When submerged cultures which normally produce acid were induced to sporulate, the culture medium shifted toward alkaline rather than acid reaction with growth.