Purification and Properties of an Enzyme Capable of Degrading the Sheath of Sphaerotilus natans

Microorganisms which can degrade and grow on the purified sheath of a sheathed bacterium Sphaerotilus natans were collected from soil and river water. Two bacterial strains were isolated from the soil and designated strains TB and TK. Both strains are rod shaped, negatively stained by gram staining, facultatively anaerobic, and formed ellipsoidal endospores. These characteristics suggested that the isolates belong to the genus Paenibacillus, according to Ash et al. (C. Ash, F. G. Priest, and M. D. Collins, Antonie Leeuwenhoek 64:253–260, 1993). Phylogenetic analysis based on the 16S rDNA supported this possibility. Purification of the sheath-degrading enzyme was carried out from the culture broth of strain TB. The molecular weight of the enzyme was calculated to be 78,000 and 50,000 by sodium dodecyl sulfate-polyacrylamide electrophoresis and gel filtration chromatography, respectively. Enzyme activity was optimized at pH 6.5 to 7.0 and 30 to 40°C. The reaction was accelerated by the addition of Mg²⁺, Ca²⁺, Fe³⁺, and iodoacetamide, whereas it was inhibited by the addition of Cu²⁺, Mn²⁺, and dithiothreitol. The enzyme acted on the polysaccharide moiety of the sheath, producing an oligosaccharide the size of which was between the sizes of maltopentaose and maltohexaose. As the reaction proceeded, the absorbance at 235 nm of the reaction mixture increased, suggesting the generation of unsaturated sugars. Incorporation of unsaturated sugars was also suggested by the thiobarbituric acid reaction. It is possible that the enzyme is not a hydrolytic enzyme but a kind of polysaccharide eliminase which acts on the basic polysaccharide.     

Detection of Novel Proline 3-Hydroxylase Activities in Streptomyces and Bacillus spp. by Regio- and Stereospecific Hydroxylation of l-Proline

During the screening of microbial proline hydroxylases, novel proline 3-hydroxylase activities, which hydroxylate free l-proline to free cis-3-hydroxy-l-proline, were detected in whole cells of Streptomyces sp. strain TH1 and Bacillus sp. strains TH2 and TH3 from 3,000 strains isolated from soil. The reaction product was purified from a reaction mixture of Streptomyces sp. strain TH1, and its chemical structure was identified as cis-3-hydroxy-l-proline by instrumental analyses. Proline 3-hydroxylase activity was also detected in Streptomyces canus ATCC 12647 which produces the 3-hydroxyproline-containing peptide antibiotic telomycin. Bacillus sp. strains TH2 and TH3 were found to accumulate cis-3-hydroxy-l-proline in culture media at 426 and 352 (mu)M, respectively. It was suggested that hydroxylation occurred in a highly regio- and stereospecific manner at position 3 of l-proline because no hydroxylation product other than cis-3-hydroxy-l-proline was observed. Proline 3-hydroxylases of these strains were first characterized on crude enzyme preparations. Since 2-oxoglutarate and ferrous ion were required for hydroxylation of l-proline, these 3-hydroxylases were thought to belong to a family of 2-oxoglutarate-related dioxygenases. The reaction was inhibited by Co(sup2+), Zn(sup2+), and Cu(sup2+). l-Ascorbic acid accelerated the reaction. The optimum pH and temperature were 7.5 and 35(deg)C, respectively.     

A novel gene encoding an enzyme that degrades a polysaccharide from the sheath of Sphaerotilus natans

A gene encoding an enzyme that is able to depolymerize the basic polysaccharide prepared from the sheath of Sphaerotilus natans was identified in a sheath-degrading bacterium, Paenibacillus koleovorans. The gene was constructed from 2217 bp coding for 738 amino acids, including the signal sequence of 34 amino acids. No closely related protein or gene was indicated by a homology search. The gene was expressed in Escherichia coli as a glutathione S-transferase fusion protein. The fusion protein depolymerized the sheath polysaccharide into an oligosaccharide, introducing an unsaturated sugar residue, suggesting that the gene codes for a polysaccharide lyase acting on a basic polysaccharide.     

A Novel Gene Encoding an Enzyme That Degrades a Polysaccharide from the Sheath of Sphaerotilus natans

A gene encoding an enzyme that is able to depolymerize the basic polysaccharide prepared from the sheath of Sphaerotilus natans was identified in a sheath-degrading bacterium, Paenibacillus koleovorans. The gene was constructed from 2217 bp coding for 738 amino acids, including the signal sequence of 34 amino acids. No closely related protein or gene was indicated by a homology search. The gene was expressed in Escherichia coli as a glutathione S-transferase fusion protein. The fusion protein depolymerized the sheath polysaccharide into an oligosaccharide, introducing an unsaturated sugar residue, suggesting that the gene codes for a polysaccharide lyase acting on a basic polysaccharide.     

Purification and characterization of pectate lyase from banana (Musa acuminata) fruits

Pectate lyase (PEL) has been purified by hydrophobic, cation exchange and size exclusion column chromatographies from ripe banana fruit. The purified enzyme has specific activity of 680 +/- 50 pkat mg protein(-1). The molecular mass of the enzyme is 43 kDa by SDS-PAGE. The pI of the enzyme is 8 with optimum activity at pH 8.5. Analysis of the reaction products by paper and anion exchange chromatographies reveal that the enzyme releases several oligomers of unsaturated galacturonane from polygalacturonate. The K(m) values of the enzyme for polygalacturonate and citrus pectin (7.2% methylation) are 0.40 +/- 0.04 and 0.77 +/- 0.08 g l(-1), respectively. PEL is sensitive to inhibition by different phenolic compounds, thiols, reducing agents, iodoacetate and N-bromosuccinimide. The enzyme has a requirement for Ca(2+) ions. However, Mg(2+) and Mn(2+) can substitute equally well. Additive effect on the enzyme activity was observed when any two metal ions (out of Mg(2+), Ca(2+) and Mn(2+)) are present together. The banana PEL is a enzyme requiring Mg(2+), in addition to Ca(2+), for exhibiting maximum activity.     

Structural analysis of the fundamental polymer of the sheath constructed by Sphaerotilus natans

The sheath of Sphaerotilus natans is composed of cysteine-rich peptide and polysaccharide moieties. The polysaccharide was prepared by treating the sheath with hydrazine, and was determined to be a mucopolysaccharide containing beta-D-GlcA, beta-D-Glc, alpha-D-GalN, and beta-D-GalN. To elucidate the structure of the peptide, the sheath was labeled with a thiol-selective fluorogenic reagent, 4-(aminosulfonyl)-7-fluoro-2,1,3-benzoxadiazole. Enantiomeric determination of the S-derivatized Cys in the fluorescent sheath suggested that it contained L-Cys mainly. Fluorescent cysteinylglycine was detected in the partial acid hydrolysate of the fluorescent sheath. The sheath-degrading enzyme secreted by Paenibacillus koleovorans produced a fluorescent disaccharide-dipeptide composed of GalN, Gly, and N-acetylated Cys from the fluorescent sheath. The disaccharide and dipeptide moieties were found to be connected by an amide bond. Based on these results, the sheath was deduced to be formed by association of a mucopolysaccharide modified with N-acetyl-L-cysteinylglycine.     

Kinetic mechanism determination and analysis of metal requirement of dehydroquinate synthase from Mycobacterium tuberculosis H37Rv: an essential step in the function-based rational design of anti-TB drugs

The number of new cases of tuberculosis (TB) arising each year is increasing globally. Migration, socio-economic deprivation, HIV co-infection and the emergence of drug-resistant strains of Mycobacterium tuberculosis, the main causative agent of TB in humans, have all contributed to the increasing number of TB cases worldwide. Proteins that are essential to the pathogen survival and absent in the host, such as enzymes of the shikimate pathway, are attractive targets to the development of new anti-TB drugs. Here we describe the metal requirement and kinetic mechanism determination of M. tuberculosis dehydroquinate synthase (MtDHQS). True steady-state kinetic parameters determination and ligand binding data suggested that the MtDHQS-catalyzed chemical reaction follows a rapid-equilibrium random mechanism. Treatment with EDTA abolished completely the activity of MtDHQS, and addition of Co(2+) and Zn(2+) led to, respectively, full and partial recovery of the enzyme activity. Excess Zn(2+) inhibited the MtDHQS activity, and isotitration microcalorimetry data revealed two sequential binding sites, which is consistent with the existence of a secondary inhibitory site. We also report measurements of metal concentrations by inductively coupled plasma atomic emission spectrometry. The constants of the cyclic reduction and oxidation of NAD(+) and NADH, respectively, during the reaction of MtDHQS was monitored by a stopped-flow instrument, under single-turnover experimental conditions. These results provide a better understanding of the mode of action of MtDHQS that should be useful to guide the rational (function-based) design of inhibitors of this enzyme that can be further evaluated as anti-TB drugs.     

Exopolysaccharide Colanic Acid and Its Occurrence in the Enterobacteriaceae

A study of strains from the genera Salmonella, Escherichia, and Aerobacter has shown that under appropriate conditions many strains produce an exopolysaccharide slime of identical composition, which has been identified as colanic acid on the basis of its chemical composition and its sensitivity to certain bacteriophage-induced depolymerase enzymes. Chemical analysis shows that the polysaccharide contains O-acetyl groups in addition to the sugars glucose, galactose, fucose, and glucuronic acid. Mild acid hydrolysis has led to the isolation of a β-glucosylfucose in addition to glucuronic acid containing oligosaccharides. Many strains were found to synthesize colanic acid under normal conditions of growth or under conditions favoring polysaccharide synthesis, whereas others only synthesized colanic acid when the control mechanism was derepressed by p-fluorophenylalanine.     

Expression of the Streptococcus pneumoniae type 3 synthase in Escherichia coli. Assembly of type 3 polysaccharide on a lipid primer.

Synthesis of the type 3 capsular polysaccharide of Streptococcus pneumoniae is catalyzed by the membrane-localized type 3 synthase, which utilizes UDP-Glc and UDP-GlcUA to form high molecular mass [3-beta-d-GlcUA-(1-->4)-beta-d-Glc-(1-->](n). Expression of the synthase in Escherichia coli resulted in synthesis of a 40-kDa protein that was reactive with antibody directed against the C terminus of the synthase and was the same size as the native enzyme. Membranes isolated from E. coli contained active synthase, as demonstrated by the ability to incorporate Glc and GlcUA into a high molecular mass polymer that could be degraded by type 3 polysaccharide-specific depolymerase. As in S. pneumoniae, the membrane-bound synthase from E. coli catalyzed a rapid release of enzyme-bound polysaccharide when incubated with either UDP-Glc or UDP-GlcUA alone. The recombinant enzyme expressed in E. coli was capable of releasing all of the polysaccharide from the enzyme, although the chains remained associated with the membrane. The recombinant enzyme was also able to reinitiate polysaccharide synthesis following polymer release by utilizing a lipid primer present in the membranes. At low concentrations of UDP-Glc and UDP-GlcUA (1 microm in the presence of Mg(2+) and 0.2 microm in Mn(2+)), novel glycolipids composed of repeating disaccharides with linkages consistent with type 3 polysaccharide were synthesized. As the concentration of the UDP-sugars was increased, there was a marked transition from glycolipid to polymer formation. At UDP-sugar concentrations of either 5 microm (with Mg(2+)) or 1.5 microm (with Mn(2+)), 80% of the incorporated sugar was in polymer form, and the size of the polymer increased dramatically as the concentration of UDP-sugars was increased. These results suggest a cooperative interaction between the UDP-precursor-binding site(s) and the nascent polysaccharide-binding site, resulting in a non-processive addition of sugars at the lower UDP-sugar concentrations and a processive reaction as the substrate concentrations increase.     

脱枝酶产生菌的分离鉴定及酶学性质研究

目的：从中国高校工业微生物资源与信息中心（CICIM-CU）细菌库中分离具有产脱枝酶酶活的细菌并鉴定,进行酶学性质的研究。方法：通过碘显色平板法筛选产酶菌株,利用16S rDNA确定其属种。对每一株产脱枝酶的细菌进行初步的酶学性质研究。结果：从4005株细菌中筛选出45株产脱枝酶的细菌,建立了产脱枝酶细菌的细菌库。酶学性质表明CICIM B272、CICIMB1-30两株菌产生的脱枝酶,酶反应的最适温度分别为70℃6、0℃,最适pH分别为6.0、5.5,来源于上述两种不同属种的脱枝酶在30-70℃反应条件下,酶在pH 4.5-8.5范围内活性稳定,Li＋、Na＋、K＋、Mg2＋、Mn2＋对两者酶活均有显著的激活作用,而Cu2＋、Fe3＋及EDTA对两者均有显著的抑制作用,Mn2＋、Ca2＋分别对两者的热稳定性具有很好的提升作用。以支链淀粉为底物的动力学常数Km分别为352.883mg/mL、4.5814mg/mL,Vmax分别为30.03mg/min.mL、0.4575mg/min.mL。结论：不同属种的脱枝酶酶学性质差别显著。     

Chemical mechanism and specificity of the C5-mannuronan epimerase reaction

C5-mannuronan epimerase catalyzes the formation of alpha-L-guluronate residues from beta-D-mannuronate residues in the synthesis of the linear polysaccharide alginate. The reaction requires the abstraction of a proton from C5 of the residue undergoing epimerization followed by re-protonation on the opposite face. Rapid-mixing chemical quench experiments were conducted to determine the nature of the intermediate formed upon proton abstraction in the reaction catalyzed by the enzyme from Pseudomonas aeruginosa. Colorimetric and HPLC analysis of quenched samples indicated that shortened oligosaccharides containing an unsaturated sugar residue form as transient intermediates in the epimerization reaction. This suggests that the carbanion is stabilized by glycal formation, concomitant with cleavage of the glycosidic bond between the residue undergoing epimerization and the adjacent residue. The time dependence of glycal formation suggested that slow steps flank the chemical steps in the catalytic cycle. Solvent isotope effects on V and V/K were unity, consistent with a catalytic cycle in which chemistry is not rate-limiting. The specificity of the epimerase with regard to neighboring residues was examined, and it was determined that the enzyme showed no bias for mannuronate residues adjacent to guluronates versus those adjacent to mannuronates. Proton abstraction and sugar epimerization were irreversible. Existing guluronate residues already present in the polysaccharide were not converted to mannuronates, nor was incorporation of solvent deuterium into existing mannuronates observed.     

Properties of a β-(1→4)-glucan hydrolase from Aspergillus niger

1. A beta-(1-->4)-glucan hydrolase prepared from Aspergillus niger, as described by Clarke & Stone (1965a), showed a pH optimum in the range 4.5-6 and K(m) 0.25% when acting on a cellulose dextrin sulphate substrate. 2. The hydrolase rapidly decreased the specific viscosity of carboxymethylcellulose with a small increase in the production of reducing sugars. The identity of the products of hydrolysis of cellotetraose, cellopentaose and their reduced analogues indicate a preferential cleavage of non-terminal glucosidic linkages. The enzyme may be described as beta-(1-->4)-glucan 4-glucanohydrolase (EC 3.2.1.4). 3. In addition to carboxymethylcellulose, cellulose dextrins, cellopentaose and cellotetraose the enzyme fraction hydrolysed lichenin, oat and barley glucans, ivory-nut mannan and a glucomannan from Konjak flour. No hydrolysis of wheat-straw beta-(1-->4)-xylan, Lupinus albus beta-(1-->4)-galactan, pneumococcal type III polysaccharide, chitin, hyaluronic acid, laminarin, pachydextrins, carboxymethylpachyman or beta-(1-->3)-oligoglucosides was detected. 4. The hydrolase showed no transglycosylase activity from cellodextrin or cellopentaose substrates to glucose or methanol acceptors. 5. The hydrolysis of cellodextrins was inhibited completely by 1.0mm-Hg(2+), 0.7mm-phenylmercuric nitrate and 1.0mm-iodine.     

胶原蛋白酶产生菌的筛选及酶的分离纯化

从堆积骨骼的土样中筛选出高产胶原蛋白酶的MBL13菌株,经鉴定为蜡样芽孢杆菌Bacillus cereus。对其所产的胶原蛋白酶BCC进行分离纯化,并进行酶学性质的研究。从菌株的发酵液中纯化出分子量约为38.0kDaBCC酶。酶反应的最适温度为40℃,最适pH为8.0。在50℃以下稳定,60℃保温1h酶活仅保留10%;在pH7.0～8.5活性较稳定;金属离子Ca2+、Zn2+、Mg2+对酶有激活作用,金属离子Cu2+对酶有显著的抑制作用。EDTA和EGTA能抑制该酶,表明BCC酶为一种金属蛋白酶。酶的底物特异性表明该酶为骨胶原蛋白酶,且对Ⅰ型骨胶原蛋白水解能力极显著高于Ⅱ型胶原蛋白和Ⅲ型胶原蛋白。将纯化的BCC酶应用于骨胶原蛋白的水解可以得到不同链长的多肽,其水解能力高于标准品胶原酶Ⅰ型。本研究为工业酶提供了新的菌株和新型胶原蛋白酶,为胶原蛋白酶的开发提供了重要的理论依据。     

Attempted isolation of a heparin proteoglycan from bovine liver capsule

(1) Polysaccharides were isolated from bovine liver capsule by extraction with 2m-potassium chloride followed by precipitation from 0.8m-potassium chloride with cetylpyridinium chloride. Chondroitin sulphate was eliminated by digestion with hyaluronidase. The yield of heparin was approx. 40% of that obtained after extraction of the papain-digested tissue. (2) The macromolecular properties of the hyaluronidase-digested polysaccharide were studied by gel chromatography on Sephadex G-200 of the intact, as well as of the alkali-degraded, material. The results suggested the presence of single heparin chains in addition to a dermatan sulphate proteoglycan. (3) A purified heparin preparation was analysed for amino acids and neutral sugars. Xylose, galactose and serine were found in amounts corresponding to 0.1, 0.2, and 0.4 residue/polysaccharide chain (mol.wt. 7400), respectively. It is suggested that the isolated material had been degraded by a polysaccharidase with endo-enzyme properties.     

Interactions between the unicellular red alga Rhodella reticulata (Rhodophyta) and contaminated bacteria

AIMS: To define the role of the bacterial strains LR1 and LR3 in the Rhodella cell destruction caused by Cytophaga sp.LR2. METHODS AND RESULTS: The bacteria were obtained from algal culture with destruction. They were isolated in pure culture and tested for biochemical activities using Polymicrotest. The ability of bacteria to degrade and utilize the algal polysaccharide was investigated. The bacteria were grown in a media containing Rhodella polysaccharide as a sole carbon source. The level of the reducing sugars in the culture media was determined. Scanning electron microscopy (SEM) was used to define the location of bacteria in extensively and intensively cultivated Rhodella reticulata previously infected by Cytophaga sp. LR2. CONCLUSIONS: The lysis of Rhodella reticulata cells is due to the joint action of the three bacterial strains with the former pathogen Cytophaga sp. LR2 playing the main role. The accumulation of the polysaccharide and the excreted metabolites of the strains LR1 and LR3 stimulated the development of Cytophaga sp. LR2. The adaptation of the strain to particular conditions of alga cultivation and the utilization of polysaccharide as a sole carbon source supported its stable growth in alga suspension and destruction of Rhodella cells. SIGNIFICANCE AND IMPACT OF THE STUDY: The predominance of Cytophaga sp. LR2 over the two other contaminants and the lysis of Rhodella reticulata cells resulted from the ability of the bacterium to attach to the algal polysaccharide sheath. The formation of slime and extrusions facilitated the phenomenon of bacterial adhesion to the algal surface as well as the formation of colonial alga - bacterial spherules. The sedimentation of these aggregates decreased the ability of the algal strain to photosynthesize, led to the lysis of the cells and finally caused the death of Rhodella.     

IMMOBILIZATION OF CARBONIC ANHYDRASE ENZYME PURIFIED FROM Bacillus subtilis VSG-4 AND ITS APPLICATION AS CO(2) SEQUESTERER

The purification, immobilization, and characterization of carbonic anhydrase (CA) secreted by Bacillus subtilis VSG-4 isolated from tropical soil have been investigated in this work. Carbonic anhydrase was purified using ammonium sulfate precipitation, Sephadex-G-75 column chromatography, and DEAE-cellulose chromatography, achieving a 24.6-fold purification. The apparent molecular mass of purified CA obtained by SDS-PAGE was found to be 37 kD. The purified CA was entrapped within a chitosan-alginate polyelectrolyte complex (C-A PEC) hydrogel for potential use as an immobilized enzyme. The optimum pH and temperature for both free and immobilized enzymes were 8.2 and 37°C, respectively. The immobilized enzyme had a much higher storage stability than the free enzyme. Certain metal ions, namely, Co(2+), Cu(2+), and Fe(3+), increased the enzyme activity, whereas CA activity was inhibited by Pb(2+), Hg(2+), ethylenediamine tetraacetic acid (EDTA), 5,5'-dithiobis-(2-nitrobenzoic acid (DTNB), and acetazolamide. Free and immobilized CAs were tested further for the targeted application of the carbonation reaction to convert CO(2) to CaCO(3). The maximum CO(2) sequestration potential was achieved with immobilized CA (480?mg CaCO(3)/mg protein). These properties suggest that immobilized VSG-4 carbonic anhydrase has the potential to be used for biomimetic CO(2) sequestration.     

Origin of Polysaccharide Depolymerase Associated with Bacteriophage Infection

Analyses, by construction of phage growth curves, indicated that the polysaccharide depolymerase was synthesized by Pseudomonas aeruginosa strains B and BI after infection with phage 2. The kinetics of biosynthesis of the depolymerase were found to parallel closely the rate of formation of phage-directed virions, and alterations in the experimental conditions of infection were reflected by alterations in the production of enzyme. Infection with other Pseudomonas phages, 84 and 1197, did not result in the synthesis of depolymerase. The enzyme was not detectable in uninfected cultures, and no evidence was obtained for the existence of inhibitors or activators of enzyme activity in extracts of uninfected or infected cells. The results of experiments employing chloramphenicol or an auxotorphic mutant (BI arg(-)) suggested that protein synthesis de novo was essential for production of the enzyme. Various mutants of phage 2 (pdp(1), pdp(2)), which alter the synthesis of the polysaccharide depolymerase, have been isolated. These experimental results strongly support the role of the phage genome in the synthesis of this enzyme.     

Purification and characterization of an epsilon-poly-L-lysine-degrading enzyme from an epsilon-poly-L-lysine-producing strain of Streptomyces albulus

An epsilon-poly-L-lysine-degrading enzyme of an epsilon-poly-L-lysine-producing strain of Streptomyces albulus was purified and characterized. The enzyme was tightly bound to the cell membrane. After solubilization with NaSCN, the enzyme was purified to homogeneity by phenyl-Sepharose CL-4B column chromatography. The subunit molecular mass of the purified enzyme was 54 kDa. Enzyme activity was inhibited by o-phenanthroline, and could be restored in the presence of 1 mM Mg(2+), Ca(2+), Fe(3+) or Zn(2+). The mode of epsilon-poly-L-lysine degradation was of the exo-type, and the enzyme released N-terminal L-lysines one by one. The enzyme acted on various peptides possessing L-lysine residues at the N-terminus and was classified as an aminopeptidase. Epsilon-Poly-L-lysine-degrading activity was found in the membrane fraction of some other Streptomyces strains as well as that of Streptomyces albulus. Streptomyces virginiae IFO 12827 and Streptomyces norsei IFO 15452 exhibited high epsilon-poly-L-lysine-degrading activity, and both strains could produce epsilon-poly-L-lysine, indicating a correlation between the distribution of membrane-bound epsilon-poly-L-lysine-degrading enzyme and epsilon-poly-L-lysine-producing activity.     

Ultrastructure and chemical composition of the sheath of Leptothrix discophora SP-6.

Light microscopy and transmission electron microscopy of thin sections and metal-shadowed specimens showed that the sheath of Leptothrix discophora SP-6 (ATCC 51168) is a tube-like extracellular polymeric structure consisting of a condensed fabric of 6.5-nm-diameter fibrils underlying a more diffuse outer capsular layer. In thin sections, outer membrane bridges seen to contact the inner sheath layer suggested that the sheath fabric was attached to the outer layer of the gram-negative cell wall. The capsular polymers showed an affinity for cationic colloidal iron and polycationic ferritin, indicating that they carry a negative charge. Cell-free sheaths were isolated by treatment with a mixture of lysozyme, EDTA, and N-lauroylsarcosine (Sarkosyl) or sodium dodecyl sulfate (SDS). Both Sarkosyl- and SDS-isolated sheaths were indistinguishable in microscopic appearance. However, the Mn-oxidizing activity of Sarkosyl-isolated sheaths was more stable than that of SDS-isolated sheaths. The Sarkosyl-isolated sheaths also contained more 2-keto-3-deoxyoctanoic acid and more outer membrane protein than SDS-isolated sheaths. The oven-dried mass of detergent-isolated sheaths represented approximately 9% of the total oven-dried biomass of SP-6 cultures; the oven-dried sheaths contained 38% C, 6.9% N, 6% H, and 2.1% S and approximately 34 to 35% carbohydrate (polysaccharide), 23 to 25% protein, 8% lipid, and 4% inorganic ash. Gas-liquid chromatography showed that the polysaccharide was an approximately 1:1 mixture of uronic acids (glucuronic, galacturonic, and mannuronic acids and at least one other unidentified uronic acid) and an amino sugar (galactosamine). Neutral sugars were not detected. Amino acid analysis showed that sheath proteins were enriched in cysteine (6 mol%). The cysteine residues in the sheath proteins probably provide sulfhydryls for disulfide bonds that play an important role in maintaining the structural integrity of the sheath (D. Emerson and W.C. Ghiorse, J. Bacteriol. 175:7819-7827, 1993).     

Degradation of unsaturated polysaccharide derived from acidic polysaccharide of Fusarium sp. M7-1 by a bacterium isolated from soil

A soil bacterium, strain no. 19, capable of using unsaturated polysaccharide derived from acidic polysaccharide of Fusarium sp. M7-1 as a sole source of carbon was isolated. The bacterium degraded about 70% of the total sugar content. Results from analysis of the degraded polysaccharide showed that the bacterium degraded the β(1→6) galactofuranoside linkage as well as the unsaturated glucuronic acid residues linked to the galactofuranoside residues via the α(1→2) linkage.