Antibiotic production by the immobilized cyanobacterium,Scytonema sp. TISTR 8208, in a seaweed-type photobioreactor

A photobioreactor was constructed using either anchored polyurethane foam strips (1 × 1 × 40 cm, PU-strips) fixed on a stainless-steel ring to prevent flotation, or free-floating polyurethane foam blocks (1 × 1 × 1 cm, PU-blocks) as biomass supporting materials (BSM). The cyanobacterium,Scytonema sp. TISTR 8208, which produces an antibiotic, was immobilized onto PU-strips or -blocks. The free-floating PU-blocks could immobilize only about 70% of the total cells, while the anchored PU-strips could immobilize as much as 97%. PU-strips were chosen as the BSM and we named this type of reactor, seaweed-type bioreactor (STB). Optimal physical conditions for antibiotic production were determined in the STB. Inoculum density was 0.4 g l^–1 and cells were sparged with air containing 5% CO₂ circulated at the gas flow rate of 250 ml min^–1 and illuminated at a light intensity of 200 mol photon m^–2 s^–1. The production of antibiotic could be increased 3-fold.Author for correspondence     

Continuous antibiotic production by an immobilized cyanobacterium in a seaweed-type bioreactor

The filamentous cyanobacterium,Scytonema sp. TISTR 8208, which produces a cyclic peptide antibiotic, was cultivated for 20 d in a seaweed-type bioreactor containing anchored polyurethan foam strips. Cells immobilized onto the foam strips produced the antibiotic for only several days, and the secreted antibiotic disappeared very rapidly from the medium. Cells accumulated the antibiotic intracellularly in a growth-related manner, and secreted it in the stationary phase. Since the antibiotic has a stable physico-chemical nature, the cells seem to take it up and metabolize it. When continuous cultivation was attempted, stable production of the antibiotic was maintained in the bioreactor for 16 d at a dilution rate of 0.01 h^–1. Three times more antibiotic was produced in the continuous culture than in the batch culture by the 16th day.     

Selective production of glutamate by an immobilized marine blue-green alga,Synechococcus sp.

Summary Among 200 strains of marine bluegreen algae isolated from the coastal areas of Japan, the marine blue-green alga Synechococcus sp. NKBG 040607 excreted glutamate at the highest rate, 82.6% of total amino acids production being glutamate. Synechococcus sp. NKBG 40607 was immobilized in calcium alginate gel. Glutamate production by immobilized cells was double that of native cells. Maximal glutamate production (25 g/cm³ gel per day) of the immobilized cells was observed under a light intensity of 144 Einstein/m² per second at a cell concentration of 7.5 mg dry cells/cm³ gel. Immobilized cells of Synechococcus sp. can use nitrate as a nitrogen source. Immobilized marine Synechococcus sp. produced 0265 mg/cm³ gel of glutamate for 7 days in the presence of chloramphenicol.     

Hydrogen production from organic substrates in an aerobic nitrogen-fixing marine unicellular cyanobacterium Synechococcus sp. strain Miami BG 043511

Synechococus sp. strain Miami BG 043511 exhibits very high H(2) photoproduction from water, but the H(2) photoproduction capability is lost rapidly with the age of the batch culture. The decreases of the capability coincides with the decrease of cellular glucose (glycogen) content. However, H(2) photoproduction capability can be restored by the addition of organic substrates. Among 40 organic compounds tested, carbohydrates such as glucose, fructose, maltose, and sucrose were effective electron donors. Among organic acids tested, only pyruvate was an effective electron donor. Among alcohols tested, glycerol was a good electron donor. These results demonstrate that this unicellular cyanobacterium exhibits a wide substrate specificity for H(2) photoproduction but has a different substrate specificity compared to photosynthetic bacteria. The maximum rates of H(2) photoproduction from a 6-day-old batch culture with 25 mmol of pyruvate, glucose, maltose, sucrose, fructose, and glycerol were 1.11, 0.62, 0.50, 0.47, 0.30, and 0.39 micromoles per mg cell dry weight per hour respectively. Therefore, this cyanobacterium strain may have a potential significance in removing organic materials from the wastewater and simultaneously transforming them to H(2) gas, a pollution free energy. The activity of nitrogenase, which catalyzes hydrogen production, completely disappeared when intracellular glucose (glycogen) was used up, but it could be restored by the addition of organic substrates such as glucose and pyruvate. (c) 1994 John Wiley & Sons, Inc.     

Thermostable amylase production by immobilized thermophilic Bacillus sp.

Agar, agarose and alginate immobilized cells of thermophilic Bacillus sp. WN11 produced 7.0, 6.2, and 10.5 U/ml of thermostable amylase in shake flasks, respectively. Alginate entrapped cells released high level of amylase (10.5 U/ml) than freely suspended cells (8.0 U/ml). Amylase production was stable in five successive batches with productivity of 9-12 U/ml for alginate, 5.5-8.8 U/ml for agar, and 4.8-8.0 for agarose immobilized cells.     

Lyngbyaureidamides A and B,two anabaenopeptins from the cultured freshwater cyanobacterium Lyngbya sp. (SAG 36.91)

Two anabaenopeptin-type peptides, lyngbyaureidamides A and B, together with two previously reported peptides lyngbyazothrins C and D, were isolated from the cultured freshwater cyanobacterium Lyngbya sp. (SAG 36.91). Their structures were determined by spectroscopic and chemical methods. Lyngbyazothrins C and D were also able to inhibit the 20S proteasome with IC₅₀ values of 7.1 μM and 19.2 μM, respectively, while lyngbyaureidamides A and B were not active at 50 μM.     

Nitrogen fixation by the benthic freshwater cyanobacterium Lyngbya wollei

The ability of the benthic cyanobacterium Lyngbya wollei to fix nitrogen was studied using field samples and axenic cultures. L. wollei was collected and isolated from Lake Okeechobee, Florida, where it forms extensive mats. Rates of acetylene reduction up to 39.1 nmol mg dry wt⁻¹ h⁻¹ were observed for field samples. The maximum observed rate of acetylene reduction in axenic laboratory cultures was 200 nmol mg dry wt⁻¹ h⁻¹. Aerobic conditions limited nitrogen fixation activity, but dark/light cycles promoted the development of activity. Reduced oxygen levels appeared to be required for the development of significant levels of nitrogenase activity. The level of irradiance also had a significant impact on the level of activity. The potential significance of nitrogen fixation to Lyngbya production is discussed.     

Hydrogen production from biodiesel byproduct by immobilized Enterobacter aerogenes

The recent rapid growth of the biodiesel industry has generated a significant amount of glycerol as a byproduct. As a result, the price of glycerol is currently relatively low, making it an attractive starting material for the production of chemicals with higher values. Crude glycerol can be directly converted through microbial fermentation into various chemicals such as hydrogen. In this study, we optimized immobilization of a facultative hydrogen producing microorganism, Enterobacter aerogenes, with the goal of developing biocatalysts that was appropriate for the continuous hydrogen production from glycerol. Several carriers were tested and agar was found to be the most effective. In addition, it was clearly shown that variables such as the carrier content and cell loading should be controlled for the immobilization of biocatalysts with high hydrogen productivity, stability, and reusability. After optimization of these variables, we were able to obtain reusable biocatalysts that could directly convert the byproduct stream from biodiesel processes into hydrogen in continuous processes.     

Kinetics of p-cresol degradation by an immobilized Pseudomonas sp.

A p-cresol (PCR)-degrading Pseudomonas sp. was isolated from creosote-contaminated soil and shown to degrade PCR by conversion to protocatechuate via p-hydroxybenzaldehyde (PBA) and p-hydroxybenzoate (PHB). Cells of the Pseudomonas sp. were immobilized in calcium alginate beads and in polyurethane foam. The relationship between the PCR concentration and the PCR transformation rate was investigated in batch and continuous culture bioreactors. The biodegradation kinetics of PBA and PHB also were investigated. In batch culture reactors, the maximum PCR degradation rate (Vmax) for the alginate-immobilized Pseudomonas sp. cells was 1.5 mg of PCR g of bead-1 h-1 while the saturation constant (Ks) was 0.22 mM. For PHB degradation, the Vmax was 0.62 mg of PHB g of bead-1 h-1 while the Ks was 0.31 mM. For polyurethane-immobilized Pseudomonas sp. cells, the Vmax of PCR degradation was 0.80 mg of PCR g of foam-1 h-1 while the Ks was 0.28 mM. For PHB degradation, the Vmax was 0.21 mg of PHB g of foam-1 h-1 and the Ks was 0.22 mM. In a continuous column alginate bead reactor, the Vmax for PCR transformation was 2.6 mg g of bead-1 h-1 while the Ks was 0.20 mM. The Vmax and Ks for PBA transformation in the presence of PCR were 0.93 mg g of bead-1 h-1 and 0.063 mM, respectively. When PHB alone was added to a reactor, the Vmax was 1.48 mg g of bead-1 h-1 and the Ks was 0.32 mM.(ABSTRACT TRUNCATED AT 250 WORDS)     

Factors influencing growth and toxin production by cultures of the freshwater cyanobacterium Lyngbya wollei Farlow ex Gomont

Collections of Lyngbya wollei were taken from Guntersville Reservoir, Alabama, over a period of three years. Healthy filaments were isolated and transferred to agar plates of Z-8 and LM6E media. Unialgal isolates were cultured for the study of growth and paralytic shellfish poison (PSP) production. Filaments were extracted and the toxins were detected using high performance liquid chromatography (HPLC) with post column oxidation followed by fluorescence detection. HPLC profiles show that laboratory cultures of L. wollei produced decarbamoyl gonyautoxin 2 and 3, plus several other PSP like toxins whose structures are under investigation. At 26 °C and a light intensity of 11 or 22 μmol m-2 s-1 optimum production of both biomass and toxins occurred. A decrease or increase in temperature or light flux caused a reduction in dry weight or toxicity. Compared to control levels, lower PO4-P and NO3-N and higher calcium levels gave rise to higher biomass and toxicity. Lower calcium, calcium- or PO4-P deficient medium and high NO3-N or PO4-P caused a large decrease in dry weight and toxicity. This revised version was published online in August 2006 with corrections to the Cover Date.     

Two-stage system for hydrogen production by immobilized cyanobacterium Gloeocapsa alpicola CALU 743

Previous studies showed that cell suspensions of unicellular nondiazotrophic cyanobacterium G. alpicola grown under nitrate-limiting conditions intensively produces H2 via fermentation of endogenous glycogen with hydrogen yield more then 90% of theoretical maximum (3.8 mol H2 per mol glucose). H2 production is realized by a Hox hydrogenase on the stages of NAD(P)H generation. Exploiting this property, the two-stage cyclic system for sustained hydrogen production was developed using a photobioreactor (PhBR) with G. alpicola immobilized on glass fiber TR-0.3. Immobilization of the cells on the matrix occurred during growth directly in PhBR operated in continuous mode; the density of culture immobilized achieved 37 g Chl alpha cm(-2). The first stage of the cycle was the photosynthetic incubations of G. alpicola in the flow of the culture medium, which contained limiting concentrations of nitrate for efficient glycogen accumulation and activation of hydrogenase. The second stage was the fermentation of glycogen, with H2 production realized in darkness with continuous Ar sparging and without medium flow. Standardization of optimal parameters for both stages provided a stable cyclic regime of the system: photosynthesis (24 hours)-fermentation (24 hours). The total amount of H2 evolved in one cycle was 957.6 mL L(-1)(matrix), and the overage rate of H2 production during the cycle (48 hours) was about 20 mL h(-1) L(-1)(matrix). Ten consequent cycles was carried out in this regime with reproducible H2 production, although PhBR with the same sample of immobilized culture was operated over a period of more then three months.     

Sustained ammonia production by immobilized filaments of the nitrogen-fixing cyanobacterium Anabaena 27893

Summary Whole filaments of the N₂-fixing cyanobacterium Anabaena ATCC 27893 have been immobilized by entrapment in calcium alginate gel beads. In a continuous flow fluidized bed reactor sustained photosynthesis, N₂-fixation, and ammonia production have been achieved over a 130 hour period, the longest tested.     

Characterization of an extracellular flocculating substance produced by a planktonic cyanobacterium, Anabaena sp.

Two planktonic cyanobacteria, Anabaena sp. N1444 and Anabaena sp. PC-1, and a green eukaryotic alga, Scene-desmus sp., produced extracellular flocculants. The flocculant of Anabaena PC-1, when purified, was found to be a macromolecular polysaccharide consisting of neutral sugars, uronic acids, and proteins, but not keto acids, hexosamines nor fatty acids. The flocculant bound a cationic dye, Alcian Blue, indicating it to be polyanionic. The flocculating activity was high under acidic conditions, slightly enhanced by the addition of salts and metals, and increased to about 40% upon heating at 100 °C for 7 min. The flocculant could flocculated various inorganic and organic compounds in solution. © Rapid Science Ltd. 1998     

Hydrogen production from glucose by immobilized growing cells ofClostridium butyricum

Summary Clostridium butyricum was immobilized in a porous carrier (acetylcellulose filter) with agar. Addition of peptone to the reaction mixture increased the hydrogen productivity from glucose. The number of cells in the agaracetylcellulose increased during incubation in the medium containing glucose and peptone, and the immobilized growing cells converted 45% of the glucose to hydrogen. Riboflavin enhanced the hydrogen productivity and the lactate produced by the native cells decreased remarkably. Therefore, the immobilized whole cells incubated with riboflavin were employed for repeated hydrogen production in the medium containing glucose and peptone. The hydrogen productivity of the immobilized cells increased markedly after repeated use, and the immobilized cells produced hydrogen in stoichiometric amounts from glucose.     

Hydrogen production by immobilized cells in the nozzle loop bioreactor

Summary The continuous production of hydrogen in a Nozzle Loop Bioreactor was investigated using immobilized Rhodospirillum rubum KS-301 with glucose as the growth-limiting substrate. The maximum hydrogen production rate in the experimental range was 91mL/h at dilution rate 0.4h^-1, initial glucose concentration 5.4g/L, and circulation rate 70h^-1 .     

Continuous production of bacitracin by immobilized living whole cells of Bacillus sp.

Whole cells of Bacillus sp., a bacitracin-producing bacteria, were immobilized in polyacrylamide gel. The continuous production of bacitracin by an immobilized whole-cell-containing air-bubbled reactor was examined with 0.5% peptone solution. The bacitracin productivity (28 units/ml/hr) obtained with this system was higher than that with a batch system. The effluent bacitracin concentration increased with increasing aeration rate and reached a steady-state maximum above the aeration rate of 3.0 liter/min. A high bacitracin productivity was retained for at least eight days when the gel was washed with sterilized saline at a flow rate of 250 ml/hr for 2 hr once a day. The half-life of the immobilized whole-cell system was about 10 days. Bacitracin productivity by the immobilized whole-cell reactor was higher than that by a conventional continuous fermentation process at high dilution rates.     

Palatinose production by free and Ca-alginate gel immobilized cells of Erwinia sp.

Palatinose is a non-cariogenic disaccharide obtained from the enzymatic conversion of sucrose, used in food industries as a sugar substitute. Free and Ca-alginate immobilized cells of Erwinia sp. D12 were used to produce palatinose from sucrose. Palatinose production was studied in a repeated-batch process using different immobilized biocatalysts: whole cells, disrupted cells and glucosyltransferase. Successive batches were treated with the immobilized biocatalyst, but a decrease in palatinose production was observed. A continuous process using a packed-bed reactor was investigated, and found to produce 55–66% of palatinose during 17 days using immobilized cells treated with glutaraldehyde and a substrate flow speed of 0.56 ml min⁻¹. However, immobilized cells in a packed-bed reactor failed to maintain the palatinose production for a prolonged period. The free cells showed a high conversion rate using batch fermentation, obtaining a palatinose yield of 77%. The cells remained viable for 16 cycles with high palatinose yields (65–77%). Free Erwinia sp. D12 cells supported high production levels in repeated-batch operations, and the results showed the potential for repeated reuse.     

Growth,photosynthesis, nitrogen fixation and carbohydrate production by a unicellular cyanobacterium,Synechococcus sp. (Cyanophyta)

A polymer-producing strain of unicellular cyanobacteria, Synechococcus sp., was isolated from a coastal lagoon in Florida. This strain, designated BG0011, excreted a highly viscous polysaccharide. Maximum observed growth rates for BG0011 were 2.5 div. day^-2. BG0011 also exhibited nitrogen fixation (nitrogenase) activity under aerobic conditions and grew at near maximum rates in medium lacking reduced nitrogen. Growth and carbohydrate production were enhanced by carbon dioxide enrichment. Rheological study of the extracellular polysaccharide revealed a viscosity versus shear rate curve similar in shape to that of xanthan gum. Maximum observed rate of carbohydrate production was 1 g dry weight liter^-1 month^-1.     

Culture of the marine cyanobacterium, Lyngbya majuscula (Oscillatoriaceae), for bioprocess intensified production of cyclic and linear lipopeptides.

Cyanobacteria are an ancient and diverse group of photosynthetic microorganisms, which inhabit many different and extreme environments. This indicates a high degree of biological adaptation, which has enabled these organisms to thrive and compete effectively in nature. The filamentous cyanobacterium, Lyngbya majuscula, produces several promising antifungal and cytotoxic agents, including laxaphycin A and B and curacin A. Samples of L. majuscula collected from Moorea Island, Tahiti (French Polynesia) and from the Culture Collection of Algae and Protozoa (CCAP 1446/4) were studied and adapted to large scale laboratory culture (5 l). This constitutes a 100-fold scale-up for the culture of this particular strain of L. majuscula. The effect of culture vessel configurations, growth conditions and media compositions on growth of L. majuscula was examined. Using optimised culture conditions, two strains of L. majuscula are currently being evaluated for their production of secondary metabolites. Results will be compared with those obtained from four environmental extracts. Comparisons were made by thin layer chromatography (TLC), high performance liquid chromatography (HPLC) and fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS). It was shown that varying the culture conditions under which L. majuscula was grown had the greatest effect on secondary metabolite production, thus providing potential for future bioprocess intensified production.