Characteristics of a biopolymer flocculant produced by Bacillus sp. PY-90

A biopolymer flocculant-producing bacterium, strain PY-90, was isolated and considered to belong to Bacillus subtilis. For the production of biopolymer flocculant by strain PY-90, a medium containing 2 to 5% l-glutamic acid as a nitrogen source was suitable. The biopolymer flocculant was a homopolymer composed of glutamic acid residues and was presumed to be poly(γ-glutamic acid). In kaolin suspension, the highest flocculating activity was attained at the biopolymer flocculant concentration of 20 mg/l. The flocculating activity was increased by the addition of Ca²⁺, and the optimum concentration of which was about 2 to 8 mM. The flocculating activity was high in an acidic pH range of 3.0 to 5.0, and decreased upon heating at 100°C.     

Poly‐γ‐glutamic acid produced from Bacillus licheniformis CGMCC 2876 as a potential substitute for polyacrylamide in the sugarcane industry

As an environmentally friendly and industrially useful biopolymer, poly‐γ‐glutamic acid (γ‐PGA) from Bacillus licheniformis CGMCC 2876 was characterized by the high‐resolution mass spectrometry and ¹H NMR. A flocculating activity of 11,474.47 U mL^?1 obtained with γ‐PGA, and the effects of carbon sources, ions, and chemical properties (D‐/L‐composition and molecular weight) on the production and flocculating activity of γ‐PGA were discussed. Being a bioflocculant in the sugar refinery process, the color and turbidity of the sugarcane juice was IU 1,877.36 and IU 341.41 with 0.8 ppm of γ‐PGA, respectively, which was as good as the most widely used chemically synthesized flocculant in the sugarcane industry—polyacrylamide with 1 ppm. The γ‐PGA produced from B. licheniformis CGMCC 2876 could be a promising alternate of chemically synthesized flocculants in the sugarcane industry. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 31:1287–1294, 2015     

Characterization and flocculating properties of an extracellular biopolymer produced from a Bacillus subtilis DYU1 isolate

Biopolymer DYU500 produced from Bacillus subtilis DYU1 was found to have excellent flocculating ability. With the addition of 40 mg-DYU500/L and 50 mM CaCO₃, the optimum temperature for flocculation performance of DYU500 was 30 °C, giving the highest flocculating activity and rate of 13.5 and 97%, respectively. Analysis with Fourier transform infrared spectrophotometry (FT-IR), nuclear magnetic resonance spectrometry (NMR) and amino acid identification shows that the DYU500 biopolymer mainly possesses the structure of poly-glutamic acid (PGA). The average molecular weight of DYU500 was about (3.16–3.20) × 10⁶ Da as determined by gel permeation chromatography. The major components of biopolymer DYU500 were total sugars, uronic acids, proteins and polyamides (homopolymer of glutamic acid), accounting for a weight ratio of approximate 14.9, 2.7, 4.4 and 48.7% (w/w), respectively. The flocculating activity of DYU500 in the kaolin suspension was markedly stimulated by the addition of bivalent cations Ca²⁺ or Mg²⁺ in optimum concentration ranges of about 0.15–0.90 and 0.10–0.90 mM, respectively. The synergistic effect of cations was most effective at a weak acidic or neutral pH (6.0–7.0). The flocculating activity of DYU500 linearly decreased with an increase in incubation temperature and the activity was completely lost when heating upon 120 °C, arising from the destruction of the polyamides structure of DYU500. Moreover, mechanisms describing the flocculation process with DYU500 were proposed based on the experimental observations.     

Rheology,oxygen transfer,and molecular weight characteristics of poly(glutamic acid) fermentation by Bacillus subtilis

Poly(glutamic acid) (PGA) is a water-soluble, biodegradable biopolymer that is produced by microbial fermentation. Recent research has shown that PGA can be used in drug delivery applications for the controlled release of paclitaxel (Taxol) in cancer treatment. A fundamental understanding of the key fermentation parameters is necessary to optimize the production and molecular weight characteristics of poly(glutamic acid) by Bacillus subtilis for paclitaxel and other applications of pharmaceuticals for controlled release. Because of its high molecular weight, PGA fermentation broths exhibit non-Newtonian rheology. In this article we present experimental results on the batch fermentation kinetics of PGA production, mass transfer of oxygen, specific oxygen uptake rate, broth rheology, and molecular weight characterization of the PGA biopolymer.     

微生物絮凝剂产生菌的筛选及其培养条件优化

从广西大学食用菌废弃料中分离出7株絮凝剂产生菌,以发酵液对高岭土悬浮液絮凝效果为指标衡量其絮凝活性及产絮凝剂能力,经过初筛与复筛,筛选到一株絮凝剂高产菌F00,初步确定属曲霉属(Aspergillus),并对其产生絮凝剂的条件进行优化.     

A novel flocculant biopolymer produced by Pestalotiopsis sp. KCTC 8637P

Summary A white rot fungus was isolated from rotted leaves and identified as Pestalotiopsis sp. KCTC 8637P. It produced a flocculant biopolymer. A flocculant was partially purified from the culture broth by series of precipitations with 95% ethanol and named as Pestan. The components of Pestan were consisted of glucose : glucosamine : glucuronic acid : rhamnose with a approximately molar ratio of 100:3.5:1.6:1.3.In kaolin suspension(final concentration was 4,800 mg/l), the highest flocculating activity was attained at the biopolymer flocculant concentration of 1 mg/l . The flocculating activity was observed most highest by the addition of cationic solutions, especially 8mM CaCl₂ · 2H₂O or 8mM FeCl₃. The thermal stability of Pestan was sustained up to 70 °C.     

Biopolymer flocculant produced by an Pseudomonas sp.

A biopolymer flocculant produced by Pseudomonas sp. A-99 had flocculating activity both in inorganic suspensions containing Ca2, Mg2 or Fe3 and in organic suspensions containing Fe2, Fe3 or Al3. The flocculant was an acidic protein and contained a small amount of an acidic polysaccharide consisting of galacturonic acid, glucose and galactose. Productivity of the flocculant was about 450 mg/l medium. © Rapid Science Ltd. 1998     

Biopolymer flocculant produced by an Enterobacter sp.

A new biopolymer flocculant was produced by Enterobacter sp. BY-29. Flocculating activity increased in the presence of Al , Fe or Fe . The flocculant had flocculating activity not only in inorganic suspensions of kaolin and active carbon but also in organic suspensions of cellulose and yeast. The flocculant was an acidic polysaccharide consisting of glucose, galactose, xylose and galacturonic acid, and its MW was about 2.5 ¥ 10 6 Da.     

Screening of flocculant-producing microorganisms and some characteristics of flocculants

Summary 27 strains of microorganisms including moulds, bacteria, actinomyces and yeasts, which produced substances that flocculated a kaolin clay, were screened. One strain, identified as Arthrobacter sp., secreted bioflocculant during growth. The flocculant (MF-6) was purified to electrophoretic homogeneity by precipitation with ethanol and gel chromatography. Its molecular weight was higher than 10⁶ Da. It could efficiently flocculate all suspended solids tested in aqueous solution and colored water like dye solution, and its flocculating ability was significantly enhanced by adding Ca²⁺, Mn²⁺, Mg²⁺, etc.     

Conditions for Production of Microbial Cell Flocculant by Aspergillus sojae AJ7002

Cultivation is reported on Aspergillus sojae AJ7002 which synthesized an extracellular bio-flocculant. Growth studies in shaking flasks and fermentors were conducted to obtain higher flocculant production. The highest level of polymer accumulation was attained after 48–72 hr cultivation at 30–34°C. The favorable substrates for polymer formation were casein, yeast extract, polypepton and amino acids, such as glutamic acid and alanine. The addition of saccharides to the medium was found to reduce the pH of the culture broths, and hence inhibit the accumulation of flocculant in the culture broth. The finding that the product was a single substance from the early stage of fermentation suggested that the polymer was not a product of cell autolysis. The components of the polymer which were produced by Asp. sojae did not vary even if the medium composition or culture condition changed. The addition of 2-ketogluconic acid, which is one of the constituents of the polymer increased the flocculating activity of the culture medium.     

Production of an exopolysaccharide bioflocculant by Sorangium cellulosum

AIMS: To isolate a new exopolysaccharide bioflocculant produced by the myxobacterium Sorangium cellulosum NUST06, and to characterize its chemical composition and expolysaccharide production relative to carbon source. METHODS AND RESULTS: Exopolysaccharide levels and biomass production by S. cellulosum NUST06 were analysed relative to carbon source. Glucose in the medium at a level of 3 g l(-1) completely inhibited cell growth and exopolysaccharide production, but low concentrations of glucose (1-2 g l(-1)) could stimulate cell utilization of starch. The chemical composition and flocculating activity of the NUST06 exopolysaccharide was investigated. The flocculant comprised 38.3% proteins and 58.5% carbohydrates, of which glucose, mannose and glucuronic acid were present at 51.3%, 39.2% and 10.5%, respectively. The flocculating activity of the NUST06 flocculant depended strongly on cations. CONCLUSIONS: It is feasible to produce an exopolysaccharide bioflocculant by the strain NUST06 in a mineral salts medium using starch as a carbon source. SIGNIFICANCE AND IMPACT OF THE STUDY: This strain may be advantageous for commercial bioflocculant production and may enrich existing knowledge of myxobacteria.     

Kinetics of molecular weight reduction of poly(glutamic acid) by in situ depolymerization in cell-free broth of Bacillus subtilis

Poly(glutamic acid) (PGA) is a water soluble, biodegradable biopolymer that is produced by microbial fermentation. Recent research has shown that poly(glutamic acid) can be used in drug delivery applications for the controlled release of paclitaxel (Taxol) in cancer treatment. The molecular weight of microbial poly(glutamic acid) is generally larger than what is required for drug delivery. As such, molecular weight reduction is a necessary step in producing poly(glutamic acid) for this application. Poly(glutamic acid) produced by Bacillus subtilis IFO 3335 was subjected to in situ depolymerization in the cell-free fermentation broth. Molecular weight reduction was measured, and an empirical kinetic model was used to correlate the experimental data. The kinetic rate constant, k, was found to be 6.92 × 10⁻⁶ h⁻¹ at pH 7.0 and 37 °C, which were the optimum depolymerization conditions.     

Biosynthesis of poly(γ-glutamic acid) from l-glutamic acid,citric acid,and ammonium sulfate in Bacillus subtilis IFO3335

Poly(-glutamic acid) (PGA) production in Bacillus subtilis IFO3335 was studied. When l-glutamic acid, citric acid, and ammonium sulfate were used as carbon and nitrogen sources, a large amount of PGA without a by-product such as a polysaccharide was produced. The time courses of cell growth, PGA, glutamic acid, and citric acid concentrations during cultivation were investigated. It was found that glutamic acid added to the medium was apparently not assimilated. It can be presumed that the glutamic acid unit in PGA is mainly produced from citric acid and ammonium sulfate. The PGA productivity was investigated at various concentrations of ammonium sulfate in the media, which caused the depression of cell growth, high productivity of PGA, and the production of PGA with a high relative molecular mass. The yield of PGA determined by gel permeation chromatography (GPC) reached approximately 20 g/l. This yield was the highest value for PGA production by B. subtilis IFO3335, suggesting that B. subtilis IFO3335 was a bacterium that could produce PGA effectively. Time courses relative to the molecular mass of PGA at various concentrations of ammonium sulfate were investigated. It was suggested that B. subtilis IFO3335 excreted a PGA degradation enzyme with the progress of cultivation and that PGA was degraded by this enzyme. Correspondence to: M. Kunioka     

Flocculation properties of xanthan produced by Xanthomonas campestris

Summary Xanthan had a flocculating activity in a kaolin suspension and high flocculating activity was obtained in the suspension (pH 7.0) adding Al³⁺, Fe³⁺ or Fe²⁺. Xanthan had high flocculating activity not only in other inorganic suspensions such as active carbon and acid clay but also in organic suspensions of cellulose and yeast. From these flocculation properties, xanthan is anticipated to be utilized in wide areas as a new biodegradable, harmless biopolymer flocculant.     

Purification and Chemical Analysis of Microbial Cell Flocculant Produced by Aspergillus sojae AJ7002

A bio-flocculant was isolated from the culture broth of Asp. sojae AJ 7002. It was partially purified by acetone or ethanol precipitation, by ion-exchange and gel chromatography, and by dialysis. The isolated polymer possessed chemical characteristics of a poly-hexosamine and a protein. Glucosamine and galactosamine were not acetylated. The flocculant contained 2-ketogluconic acid, but sulfur or phosphorus was not detected. This flocculant was thermo-stable and its activity varied with pH. It was suggested that the hexosamine moiety in the polymer played a major role in bio-flocculation, assisted by protein portion in enlargement of the molecular weight of the flocculant, and by 2-ketogluconic acid in endowing it with amphoteric character.     

Production of a Bioflocculant by Rhodococcus erythropolis S-1 Grown on Alcohols

Rhodococcus erythropolis strain S-1, which was isolated from soil, produces a bioflocculant. We have found that alcohols are useful carbon sources for its flocculant production. Ethanol was best for flocculant production and culture time. The bioflocculant produced on ethanol medium flocculated a wide range of suspended soils, alkaline and acid.     

Microbial flocculant from Arcuadendron sp. TS-49

Summary A flocculant was purified from the culture broth of Archuadendron sp. TS-49 by a series of precipitations with acetone, 60% ammonium sulfate-butanol, salting-out by dialysis, and cetylpyridinium chloride. The flocculating activity was observed most highly at pH 3.0 and markedly enhanced by the addition of salts, especially in the case of FeCl₃ or FeSO₄. This bioflocculant efficiently flocculated all tested solids, including various microorganisms and organic/ inorganic materials. Qualitative analyses of the bioflocculant showed that it might contain hexosamine, uronic acid, neutral sugar, and protein.     

Harvest of Scenedesmus sp. with bioflocculant and reuse of culture medium for subsequent high-density cultures

The optimal flocculating conditions for harvesting high-density cultures of Scenedesmus sp. were investigated using inorganic coagulants and the bioflocculant produced by Paenibacillus polymyxa AM49. The flocculated medium as nutrients for subsequent algal cultivation was also tested. Consecutive treatment with 8.5 mM CaCl(2) and 0.2 mM FeCl(3) as coagulants and 1% bioflocculant from the culture broth of P. polymyxa AM49 showed the highest flocculating activity of up to 95% for high density algal cultures. The medium flocculated with the coagulants and bioflocculant showed less than 8% decrease in the growth yield in the subsequent algal cultivation. Furthermore, a 20% or 50% fresh BG11 medium supplement allowed the flocculated medium to maintain a high growth yield in subsequent algal cultivation. These results suggest that the flocculation method presented here is efficient and bio-friendly, and allows the reuse of the flocculated medium, thereby contributing to the economic cultivation and harvest of microalgae.     

巨大芽孢杆菌青霉素酰化酶在枯草杆菌中的表达及其分离纯化

青霉素酰化酶（ＰＧＡ）在医药工业起着重要的作用,它能够水解青霉素Ｇ产生６－氨基青霉烷酸（６－ＡＰＡ）和苯乙酸,６－ＡＰＡ是半合成青霉素的关键中间体．该酶广泛存在于各种微生物中如真菌和细菌中．国际上对Ｅ．ｃｏｌｉ、Ａｒｔｈｒｏｂａｃｔｅｒｖｉｓｃｏｓｕ...     

The flocculation of bacteria using cationic synthetic flocculants and chitosan

Summary Bacteria are flocculated with high molecular weight cationic synthetic flocculants and chitosan. High charge density polymers are the most effective of the synthetic flocculants. Only chitosan is effective in flocculating the E. coli and B. subtilis cultures in complex broth. The difference in effectiveness between the synthetic flocculants and chitosan for flocculating E. coli, B. subtilis and Z. mobilis may be attributed to hydrogen bonding between the polysaccharide flocculant and cell surface polymers in addition to electrostatic interactions, and, in complex media, complexation of synthetic polymers with anionic polyelectrolytes.