Large Amounts Of Extracellular Polysaccharide Research Articles

Highly efficient production and characterization of the exopolysaccharides from a thermotolerant Bacillus sp.

One thermotolerant Bacillus strain SFLV-ZM107 which could produce large amounts of extracellular polysaccharides (EPS) at 50°C was identified as Bacillus licheniformis by 16S rDNA sequencing and physiological and biochemical experiments. The EPS was identified as levan fructan by monosaccharides determination, NMR, and FTIR. Strain SFLV-ZM107 can be grown in the range of 35-55°C and it is efficient to produce levan from 400 to 500 g l-1 of sucrose. The production of levan can reach 158 g l-1 in a 5 L tank fermentation with an initial sucrose concentration of 450 g l-1 at 50°C for 12 hours with a maximum productivity of 13.17 g l-1 h-1. To the best of our knowledge, the strains obtained in this study are the most productive and efficient, which has great prospects for industrial application.

Insight into biofilm-forming patterns: biofilm-forming conditions and dynamic changes in extracellular polymer substances.

The microbial biofilm adheres to the surface of the carrier, which protects the pollutant-degrading bacteria and resists harsh environments; thus, research on biofilm-forming patterns will help promote the application of biofilms in wastewater treatment. Herein, univariate analysis and response surface methodology (RSM) confirmed that glucose and mannose at 3-5g/L promoted biofilm formation. Notably, the microplate method demonstrated that compared to trivalent cations, divalent cations could more greatly enhance the activity (especially magnesium) of the biofilm matrix, and the period of biofilm formation in the three strains was divided into the following stages: initial attachment (0-10h), microcolony (10-24h), maturation (24-48h), and dispersion (36-72h). During maturation, large amounts of extracellular polysaccharides (EPs) and extracellular DNA (eDNA) were distributed in the extracellular and intracellular spaces, respectively, as observed by super-resolution structured illumination microscopy (SR-SIM). This study enhances the understanding of the characteristics and patterns of biofilm formation and can facilitate the application of biofilms in wastewater treatment.

Production and Composition of Extracellular Polysaccharide Synthesized by Rhizobium undicola Isolated from Aquatic Legume, Neptunia oleracea Lour.

Symbiont isolated from root nodules of Neptunia oleracea, an aquatic legume, designated as N37. It was identified as a Rhizobium undicola based on phenotypic characterization, 16S rRNA gene-based phylogenetic approach and whole genome relatedness. The R. undicola strain N37 was able to produce a large amount of extracellular polysaccharide in yeast extract mannitol medium. The growth and extracellular polysaccharide production started simultaneously and both had same stationary phases. Attempts were made to optimize the cultural requirements for maximum growth and extracellular polysaccharide production. The production increased enormously (515 µg/ml) with supplementation of preferred carbon, nitrogen and vitamin sources. Gas chromatographic analysis of extracellular polysaccharide isolated from R. undicola strain N37 revealed the presence of galactose (94.17 %) as predominant monomers together with very small amount of mannose (5.83 %). Fourier transformation infrared spectroscopy of extracellular polysaccharide indicated the presence of hydroxyl, methyl and carboxylate groups. The possible role of extracellular polysaccharide production on symbiosis was briefly discussed.

The extracellular polysaccharide produced by Rhizobium sp. isolated from the root nodules of Phaseolus mungo

The symbiont isolated from root nodules of Phaseolus mungo L., a widely grown legume in India was identified as a Rhizobium sp. a Rhizobium sp. close to R. multihospitium based on a biochemical and 16S rRNA gene-based phylogenetic approach. This Rhizobium sp. was able to produce large amounts of extracellular polysaccharides (EPS) in a yeast extract mannitol (YEM) broth medium. Both growth and EPS production started simultaneously though each had different stationary phases. EPS production increased enormously with supplementation by the preferred carbon, nitrogen and vitamin sources. Attempts were made to optimize the cultural requirements for maximum growth and maximum EPS production. The EPS produced by the symbiont contained large amount of mannose together with small amounts of arabinose and xylose. The possible role of EPS production on the Rhizobium—root nodule symbiosis is briefly discussed.

Extracellular polysaccharide (EPS) production by a novel strain of yeast-like fungus Aureobasidium pullulans

A yeast-like fungus producing a large amount of extracellular polysaccharide was isolated from the biogas reactors at North Wyke Research, UK (latitude, 50°46′29″N; longitude, 3°55′23″W). This strain was identified as Aureobasidium pullulans based on nucleotide sequence of the D1/D2 domain of the large-subunit (LSU) rRNA gene. Extracellular polysaccharide or pullulan, produced from this new strain of A. pullulans in shake flasks and a stirred tank fermenter was investigated. A maximum polysaccharide concentration of 40.1 g l −1, and productivity of 12.5 g l −1 per day was obtained in a batch culture from stirred tank fermenter. The optimal cultivation conditions for pullulan production for this strain in 250 ml shake flask containing 100 ml of sucrose medium were observed at 28 °C and with 200 rpm. The effect of different sugars and nitrogen sources on pullulan production was investigated. It was found that more pullulan was produced when the strain was grown in the medium supplemented with NaNO 3 than when it was cultivated in the medium supplemented with C5 and C6 sugars and other nitrogen sources.

A pivotal role for theStreptococcus iniaeextracellular polysaccharide in triggering proinflammatory cytokines transcription and inducing death in rainbow trout

Streptococcus iniae is a major pathogen of fish, causing considerable economic losses in Israel, the United States and the Far East. Containment of mortalities through vaccination was recently compromised due to the emergence of novel vaccine-escape strains that are distinguished from previous strains by their ability to produce large amounts of extracellular polysaccharide (EPS) that is released to the medium. In vitro and in vivo data now indicate that the EPS is a major virulence factor, capable of triggering the proinflammatory cytokine machinery and inducing mortality of fish. Streptococcus iniae EPS might therefore be considered to be responsible for sepsis and death just as lipopolysaccharide is for Gram-negative pathogens.

Mucilaginibacter gossypii sp. nov. and Mucilaginibacter gossypiicola sp. nov., plant-growth-promoting bacteria isolated from cotton rhizosphere soils

Two isolates from rhizosphere soil of cotton, designated Gh-67(T) and Gh-48(T), which produced large amounts of extracellular polysaccharide and possessed plant-growth-promoting traits, were characterized phenotypically and genotypically. The strains were Gram-negative and cells were non-motile rods that grew optimally at 28°C and grew between pH 4 and 7. 16S rRNA gene sequence analysis of strains Gh-67(T) and Gh-48(T) placed them in the genus Mucilaginibacter, with pairwise sequence similarity between them and type strains from related genera ranging from 93.9 to 98.2 %. The major fatty acids were iso-C₁₅:₀, C₁₆:₀ and summed feature 3 (C₁₆:₁ω7c and/or iso-C₁₅:₀ 2-OH). The strains contained MK-7 as the major isoprenoid quinone. The DNA G+C contents of strains Gh-67(T) and Gh-48(T) were 46.7 and 44.2 mol%, respectively. The low DNA-DNA hybridization value (18 %) and a number of phenotypic differences between strains Gh-48(T) and Gh-67(T) indicated that they represent two separate species. Results of phenotypic, phylogenetic and genotypic analysis revealed that the strains were separated from the species of Mucilaginibacter described to date. Therefore, strains Gh-67(T) and Gh-48(T) represent novel species of Mucilaginibacter, for which we propose the names Mucilaginibacter gossypii sp. nov. (type strain Gh-67(T) =NCIMB 14470(T) =KCTC 22380(T)) and Mucilaginibacter gossypiicola sp. nov. (type strain Gh-48(T) =NCIMB 14471(T) =KCTC 22379(T)).

Emergence of Novel Streptococcus iniae Exopolysaccharide-Producing Strains following Vaccination with Nonproducing Strains

Streptococcus iniae is a major pathogen of fish, producing fatal disease among fish species living in very diverse environments. Recently, reoccurrences of disease outbreaks were recorded in rainbow trout (Oncorhynchus mykiss, Walbaum) farms where the entire fish population was routinely vaccinated. New strains are distinguished from previous strains by their ability to produce large amounts of extracellular polysaccharide that is released into the medium. Present findings indicate that the extracellular polysaccharide is a major antigenic factor, suggesting an evolutionary selection of strains capable of extracellular polysaccharide production.

Influence of nutrient ratios on the in vitro extracellular polysaccharide production by marine diatoms from the Adriatic Sea

Three different species of marine diatoms, <it>Nitzschia closterium</it> (Ehr) Smith, <it>Chaetoceros</it> sp. (Ehr) and <it>Skeletonema costatum</it> (Grev) Cleve, were isolated from the Adriatic sea and studied <it>in vitro</it> for the production of extracellular carbohydrates. Variations of the nitrogen (N)/phosphorus (P)/silicon (Si) ratios in the growth medium affect the accumulation and release of carbohydrates. In the<it>N.closterium</it> cultures at high N/P ratio, the rate of extracellular polysaccharide release was higher both in rapidly growing cells (2.14 <IMG SRC="/math/mu.gif">g per 10⁶ cells day^-1 and in stationary phase (1.0 &mgr;g per 10⁶ cells day^-1) compared to <it>S.costatum</it> and <it>Chaetoceros</it> sp. Instead, at low N/P ratios, <it>S.costatum</it> and<it>Chaetoceros</it> sp. produced large amounts of extracellular polysaccharides during the logarithmic phase, compared to<it>N.closterium</it>, with values of 10 &mgr;g per 10⁶ cells day^-1 for<it>S.costatum</it> and 2.8 &mgr;g per 10⁶ cells day^-1 for<it>Chaetoceros</it> sp., respectively; in particular, only<it>S.costatum</it> was able to produce extracellular carbohydrates (1.2 &mgr;g per 10⁶ cells day^-1) during the stationary phase of growth. Under Si limitation, any of the three diatom species produce extracellular polysaccharides both in the logarithmic and stationary phase of growth. The potential ecological significance of these findings is discussed.

Production of extracellular polysaccharides by aRhizobium species from the root nodules ofMelilotus alba

The Rhizobium sp., isolated from the root nodules of the leguminous fodder herb Melilotus alba, produced large amounts of extracellular polysaccharides (EPS) (963.5 μg/ml) in a yeast extract mannitol medium. Growth and EPS production started simultaneously, but EPS production reached its maximum during the stationary phase of growth of the bacteria, at 20 hours. EPS production was increased with all of the thirteen sugars tested. Different nitrogen sources, such as nitrates, glutamic acid, casamino acid and L-asparagine, increased the EPS production although it was inhibited by glycine, nitrite and ammonium salts. Among the vitamins and metal ions, only pyridoxal phosphate and ZnSO4 promoted EPS production. Attempts were made to optimize the cultural requirements for growth and maximum EPS production. Maximum EPS production (1457.0 μg/ml) was obtained when the medium was supplemented with glucose (1%), pyridoxal phosphate (2 μ g/ml), ZnSO4 × 7 H2O (10 μg/ml) and glutamic acid (0.1%). Under these conditions, the production was increased by 254.3% compared to the control. The EPS contained arabinose, xylose and rhamnose monomers. The presence of arabinose and xylose in the EPS produced by a Rhizobium sp. was uncommon.

Biofouling in membrane systems — A review

The use of microbiocides, particularly chlorine may be advantageous to operation but can also exacerbate biofouling problems. Micro-organisms subjected to low levels of biocides often exude large amounts of extracellular polysaccharides (EPS) as a protection, and it is this EPS material that forms the biofilm. This paper examines the causes and effects of obstinate biofilms in membrane elements. In these cases problems of increased differential pressure have proven difficult to correct during routine cleaning cycles. Consequently, regrowth rates, as indicated by this differential pressure for such biofilms have been rapid. Experimental data has been taken from more than a hundred membrane autopsies from around the world. These autopsies have been undertaken when such problematic biofilms are encountered. These confirm that biofilms formed in process and membrane systems are comparable except that membrane biofilms contain greater numbers of fungi. Some operating systems have reported the cessation of chlorination with a significant reduction of biofouling. The paper considers possible causes for this. It also considers the increasing use of proprietary non-oxidising microbiocides. Conclusions are that biofouling is endemic within membrane systems, yet many systems operate satisfactorily even with a biofilm. Foulant layers can be ‘conditioned’ or ‘hardened’ by the repeated use of cleaning programmes and there is a strong case for alternating cleaners and biocides as used by the cooling water treatment industry.

Fixation and utilization of carbon dioxide by microalgal photosynthesis

New microalgae were isolated as candidates for CO 2 fixing biocatalyst. A new species of marine green alga, Chlorococcum littorale, exhibited the greatest CO 2 fixation rate among the isolates, r g CO 2 I −1 d −1 at pCO 2 0.2. A unicellular red alga, Galdieria partita, showed the growth at pH 1, pCO 2 1, 50 °C, and 50 ppm SO 2 aeration. A newly identified Prasinophyte, Prasinococcus capsulatus, produced a large amount of extracellular polysaccharide that could be utilized as useful resources.

河川水から分離された細菌が産生する菌体外多糖類に関する研究

In order to find new thickening agents or emulsifiers which possess uselful characteristics forfood industries, we attempted screening of microorganisms from soli and water. As a result, we found one bacterial strain which produced a large amount of extracellular polysaccharide from Sumida River in Tokyo. The strain was identified as Klebsiella pneumoniae in conformity to Bergey's Manual of Systematic Bacteriology (1984). The polysaccharide (BS-1) produced by this strain showed higher viscosity than known thickening agents such as xanthan gum, carrageenan and tragacanth gum. The viscosity of 1% (w/v) BS-1 at 20°C reached 7000cps under the shear rate of 1/S. Besides, BS-1 possessed a good property as an emulsifier. When we made emulsions of O/W=3/7 using several emulsifiers involving BS-1 and observed after 3 days of storage at room temperature, it was found that BS-1 stabilized the emulsion at the concentration of as low as 0.1% (w/v), and that the emulsion kept its creamy smoothness.

Colonial heterogeneity of Thiobacillus versutus.

In acetate-limited chemostat cultures started with single-colony cultures of Thiobacillus versutus, a mutant appeared after approximately 85 volume changes. The inhomogeneity of the culture was detected by the development of two different types of colonies on agar plates. When a pure culture of the mutant was grown in a chemostat, parent colonies appeared after almost the same period of time. Electron micrographs of the mutant grown on butyrate showed the presence of fibrils surrounding the cells. The cells of the parent strain were bald when grown under the same conditions. The growth kinetics of the parent and the mutant were investigated in batch cultures with a variety of substrates and were found to be identical. Major differences between the two strains were observed during growth on mannitol; the mutant attained a lower yield and excreted large amounts of extracellular polysaccharides.

Lipopolysaccharide-Defective Mutants of the Wilt Pathogen Pseudomonas solanacearum

Lipopolysaccharide (LPS)-defective mutants of Pseudomonas solanacearum were used to test the hypothesis that differences in LPS structure are associated with the ability or inability of different strains to induce a hypersensitive response (HR) in tobacco. To obtain these mutants, LPS-specific bacteriophage of P. solanacearum were isolated and used to select phage-resistant mutants of the virulent, non-HR-inducing strain K60. The LPS of 24 of these mutants was purified and compared with that of K60 and its HR-inducing variant, B1. Upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis, LPS from K60 and other smooth strains separated into many evenly spaced bands that migrated slowly, whereas LPS from B1 and most phage-resistant strains separated into one to three bands that migrated rapidly. Carbohydrate analysis showed that the LPS of the phage-resistant strains lacked O-antigen sugars (rhamnose, xylose, and N-acetylglucosamine) and could be grouped into (i) those that had all core sugars (rhamnose, glucose, heptose, and 2-keto-3-deoxyoctonate), (ii) those that had no core rhamnose, and (iii) those that lacked all core sugars except for 2-keto-3-deoxyoctonate. The LPS composition of 10 of the rough, phage-resistant mutants was similar to that of the HR-inducing strain, B1, yet none of them induced the HR. Only 2 of 13 mutant strains tested caused wilting of tobacco, and these had rough LPS but produced large amounts of extracellular polysaccharide, unlike most LPS-defective mutants. The evidence did not support the hypothesis that the initial interaction between rough LPS and tobacco cell walls is the determining factor in HR initiation.

Polymer-Producing Species of Arthrobacter

Gasdorf, Helen J. (Northern Regional Research Laboratory, Peoria, Ill.), R. G. Benedict, M. C. Cadmus, R. F. Anderson, and R. W. Jackson. Polymer-producing species of Arthrobacter. J. Bacteriol. 90:147-150.1965.-Two slime-producing microorganisms, designated as NRRL B-1973 and NRRL B-1797, were isolated from a Guatemalan soil sample. Their morphological and physiological characteristics permit their assignment to the genus Arthrobacter. Both cultures produce a large amount of extracellular polysaccharide, the maximal amount being 1.4 g per 3 g of glucose. The carbohydrate constituents of B-1973 polysaccharide are galactose, glucose, and mannuronic acid; those of B-1797 are galactose, glucose, and glucuronic acid. The organisms are morphologically and physiologically alike. The differences between these two cultures and previously described species of Arthrobacter appear sufficient to designate a new species. The name Arthrobacter viscosus sp. n. is proposed.