Removal of color from kraft mill wastewaters with cultures of white-rot fungi and with immobilized mycelium of Coriolus versicolor

Screening fifteen strains of white-rot fungi for their ability to decolorize combined bleached kraft effluent showed that Coriolus versicolor in liquid culture removed over 60% of the color of the effluent within six days in the presence of sucrose. Treatment of the same effluent with this fungus, immobilized in beads of calcium alginate gel, resulted in 80% decolorization after three days in the presence of sucrose. Caustic extraction E(1) effluent was also decolorized by the immobilized fungus. Decolorization was achieved more rapidly at pH 5.0 than at pH 7.0. Recycled beads could remove color efficiently and repeatedly in the presence of air but not under anaerobic conditions.     

Morphological development of Aspergillus niger immobilized in Ca-alginate and K-carrageenan

Summary The morphological development of citric acid producing Aspergillus niger immobilized in Ca-alginate and K-carrageenan was studied. The fungus normally developed a dense mycelium layer below and on the gel bead surfaces so that substrate and oxygen in this area had direct contact with mycelia. By this way mycelia are not only immobilized by entrapment but also in a pellet-like matter.Limitation of the nitrogen source induces a more interior mycelium growth, and outgrowing of free cells was minimized. In sucrose media no effect on the particle stability was observed whereas the application of potassium acetate as substrate caused the complete dissolving of the matrices.     

Phenolics production by encapsulated Nicotiana tabacum cells

Plant cells of tobacco (Nicotiana tabacum L.) were grown for several generations in suspension cultures. Cells were immobilized in continuous bioreactors in calcium alginate (Ca Alg) beads or in poly-L-lysine (PLL) encapsulated calcium alginatehydrogels. In each case, the cells were fed continuously a modified Linsmaier-Skoog plant cell culture medium. The bioreactor effluent was analyzed for total phenolic compounds. The net specific productivity of phenolics was calculated on a daily basis for several test runs. For comparison, productivity in suspension cultures was monitored. Productivity of suspended cells declined to zero within 9 d; both immobilized and encapsulated cells remained productive for 16 d following inoculation. Specific productivity by encapsulated cells was higher than that by immobilized cells; in both types similar rates of decline in productivity occurred.     

Continous production of 1-kestose by β-fructofuranosidase immobilized onshirasu porous glass

Summary 1-Kestose was produced continously and selectively from 40% (w/v) sucrose solution at fast flow rate by a column packed with an immobilized -fructofuranosidase onshirasu porous glass.     

De-colourization of textile effluent using immobilized Geotrichum candidum: an insight into mycoremediation

Textile effluent is generally complicated to manage because of its extremely noxious and recalcitrant coloured compositions. Mycoremediation is an extensively used strategy for the competent degradation of hazardous pollutants present in textile effluent. Fungus could be immobilized in synthetic or natural matrices. The current study shows the decolourization of the textile effluent by 85·5 and 98·5% within 6 h using suspended and immobilized fungus, Geotrichum candidum with optimized parameters like inoculum size (5%), pH (4·5), and temperature (30°C). To maintain a high biomass of fungal population and enhance the retention of fungal strain in the contaminated sites, the fungi need to be immobilized. Hence, the fungus was immobilized naturally onto the selected inert support that is, coconut fibres by the means of adsorption, where they grew as active films on the fibres after being grown in the culture broth. The optimized process parameters of inoculum size, fibre quantity and agitation speed for immobilized G. candidum were 5%, 2·2 g l⁻¹ of effluent and 100 rev min⁻¹ respectively. High level of laccase (22 and 25 U l⁻¹ in suspended and immobilized fungal cells treatment respectively) was observed during the process of decolourization and it was found that decolourization was directly proportional to the laccase activity. The UV–vis, FTIR, ¹H NMR and GC-MS analyses of treated textile industrial wastewater revealed the degradation of toxic pollutants in the textile effluent and formation of lower molecular weight intermediates. The study revealed a higher efficacy of immobilized G. candidum in comparison to suspended fungal culture, employing ligninolytic enzyme laccase, which catalyzes the degradation/transformation of aromatic dyes in the textile effluent thus decolourizing it.     

A novel Acinetobacter sp. for treating highly acidic rubber latex centrifugation effluent

Summary A novel Acinetobacter sp. BTJR-10 isolated from highly acidic (pH 2.5–4.5) rubber latex centrifugation effluent with high COD (22000 mg/L) and BOD (5000 mg/L). This strain could effect 39.5% COD reduction on free cell inoculation of effluent without incorporation of additional nutrients after 8 days. Calcium alginate immobilized cells showed 16.4% and 25% COD reduction after 6 hrs. without aeration and after 1 hr. with mild aeration under batch process respectively. Whereas 44.0% COD reduction could be achieved after 6 hrs. on continuous treatment in a packed bed reactor with mild aeration. Further, even after 3 cycles 37% COD reduction was recorded with continuous treatment.     

Monitoring and control of enzymic sucrose hydrolysis using on-line biosensors

Summary Previously reported flow microcalorimeter devices for enzymic reaction heat measurement, enzyme thermistors, have here been extended with systems for on-line sample treatment. Glucose analysis was performed by intermittent flow injections of 50 l samples through such an enzyme thermistor device containing immobilized glucose oxidase and catalase. Sucroce analysis was performed by allowing diluted samples to continuously pass through an additional enzyme thermistor containing immobilized invertase. The reaction heats were recorded as temperature changes in the order of 10–50 m°C for concentrations of 0.05–0.30 M glucose or sucrose present in the original non-diluted samples.The performance of this system was investigated by its ability to follow concentration changes obtained from a gradient mixer. The system was applied to monitoring and controlling the hydrolysis of sucrose to glucose and fructose in a plug-flow reactor with immobilized invertase. The reactor was continuously fed by a flow of scurose of up to 0.3 M (100 g/l). Glucose and remaining sucrose were monitored in the effluent of the column. By using flow rate controlled feed pumps for sucrose and diluent the influent concentration of sucrose was varied while the overall flow rate remained constant.On-line control of the effluent concentration of lucose and sucrose was achieved by a proportional and integral regulator implemented on a microcomuter. Preset concentration of glucose in the effluent could be maintained over an extended period of time espite changes in the overall capacity of the invertase reactor. Long delay times in the sensor system and the enzyme column made it necessary to carefully tune the control parameters. Changes of set-point value and temperature disturbances were used to verify accuracy of controlling performance.     

Studies on decolourization, degradation and detoxification of chlorinated lignin compounds in kraft bleaching effluents by Ceriporiopsis subvermispora

Ceriporiopsis subvermispora CZ-3, a wood degrading white rot fungus, was able to decolourize and degrade the first extraction stage effluent from kraft pulp bleaching at lower co-substrate concentration than the basidiomycetes previously investigated. With glucose at 1 g l⁻¹, this fungus removed up to 90% colour, 45% COD, 62% lignin, 32% AOX, and 36% EOX in 48 h at temperatures of 30–35°C and pH 4.0–4.5. In the absence of glucose, the fungus removed up to 62% of the colour. Significant reduction in chlorinated aromatic compounds was observed and toxicity to zebra fish was completely eliminated. The fungal mycelium could be immobilized in polyurethane foam and used repeatedly to treat batches of effluent. The molecular weight of chlorolignins was substantially reduced.     

Bioremediation of pulp and paper mill effluent by a novel fungal consortium isolated from polluted soil

Two basidiomycetous fungi (Merulius aureus syn. Phlebia sp. and an unidentified genus) and a deuteromycetous fungus (Fusarium sambucinum Fuckel MTCC 3788) were isolated from soils affected with effluents of a pulp and paper mill over several years. These isolates were immobilized on nylon mesh and the consortium was used for bioremediation of pulp and paper mill effluent in a continuously aerated bench-top bioreactor. The treatment resulted in the reduction of color, lignin and COD of the effluent in the order of 78.6%, 79.0% and 89.4% in 4 days. A major part of reductions in these parameters occurred within first 24h of the treatment, which was also characterized by a steep decline in the pH of the effluent. During this period, total dissolved solids, electrical conductivity and salinity of the effluent also registered marked decline. It is pertinent to note that this is the first report of bioremediation of pulp and paper mill effluent by an immobilized fungal consortium.     

Diacetyl production by immobilized citrate-positiveLactococcus lactis subsp.lactis 3022 in the fibrous Ca-alginate gel

Summary Diacetyl production by (Citr^*)Lactococcus lactis subsp.lactis 3022 was found to be an oxygen-dependent reaction. The diacetyl production by the cells immobilized in conventional Ca-alginate gel beads (Diameter: 3 mm) was lower than that of the cells immobilized in Ca-alginate gel fibers (Diameter: 0.2 mm), probably because oxygen transfer to the immobilized cells is better in gel fibers than in gel beads.     

Sucrose syrup from carob pod

Summary The ripe carob pod (pericarp) is rich in water-soluble sugars, mainly sucrose (63% on total sugars). Sucrose crystallization from aqueous carob extract is prevented by its reducing sugar content. The selective consumption of these sugars by mixed culture ofRhizopus oligosporus andSaccharomyces rouxii gives a sucrose syrup suitable for several uses e.g. sucrose extraction.     

Polysaccharide production by sponge-immobilized cells of the fungus Aureobasidium pullulans

T.P. WEST AND B.R.-H. STROHFUS. 1996. Cells of the fungus Aureobasidium pullulans ATCC 42023 were immobilized in sponge cubes and examined for their ability to elaborate the polysaccharide pullulan in relation to carbon source. It was found that fungal cells grown on corn syrup, sucrose or glucose as a carbon source could be immobilized in sponge cubes and that comparable cell weights and viable cell concentrations were immobilized. Independent of the carbon source tested, the immobilized fungal cells could be used at least three times for the production of polysaccharide. The immobilized A. pullulans cells elaborated the highest polysaccharide levels in the culture medium after 5–7 d of growth at 30°C.     

Kinetics of repeated batch production of ethanol by immobilized growing yeast cells

Summary Kinetic and yield parameters for growth and ethanol production from sucrose (100 g/l) bySaccharomyces cerevisia entrapped in K-carrageenan and calcium alginate were identical to those of free cells. Cell leakage was minimum with calcium alginate gel. For the sixth batch, 4.51 g/lh ethanol productivity (94% conversion of sucrose) was obtained; 60.5 g/l of ethanol was obtained from 200 g/l sucrose with 83.2% conversion, indicating inhibition effects.     

Cellulase production byTalaromyces emersonii CBS 814.70 co-immobilized with cellulose in calcium alginate

Summary The thermophilic fungusTalaromyces emersonii CBS 814.70 was co-immobilized with cellulose in calcium alginate beads. Cellulose production by this system was compared with a conventional process. The immobilized system continued to produce enzyme in a batch-fed reactor system while the non-immobilized had ceased production; levels of enzyme produced by the immobilized system were almost twice the maximum produced by the non-immobilized system.     

Immobilization ofβ-fructofuranosidase fromAureobasidium sp. ATCC 20524 on porous silica

Summary -Fructofuranosidase P-1 fromAureobasidium sp. ATCC 20524, which produces a fructo-oligosaccharide (1-kestose) from sucrose, was immobilized covalently onto alkylamine porous silica with glutaraldehyde at high efficiency (44.4%). Optimum pore diameter of porous silica for immobilization of the enzyme was 91.7 nm. The enzymatic profiles of immobilized enzyme were almost identical to the native one except its stabilities to temperature and metal ions were improved. 1-Kestose was produced continuously and selectively from 40% (w/v) sucrose at fast flow rates by a column packed with the immobilized enzyme for up to 26 days, and the effluent concentration of 1-kestose remained in the range 113–135 mg ml^–1.     

Immobilization of hydrogenases for biophotolytic hydrogen production; stability and kinetics

Summary Hydrogenases from Clostridium pasteurianum and Desulfovibrio desulfuricans were immobilized on solid supports with retention of 50% activity. The immobilized enzymes were more stable than the free enzymes and were active in the biophotolytic hydrogen production from water.     

Ethanol production by Zymomonas mobilis CP4 from sugar cane chips

Summary The fermentation of large sugar cane chips (1.0–1.5 in) to ethanol by Zymomonas mobilis CP4 (Z. mobilis) was studied in two glass fermentors operating with culture circulation for agitation (the EX-FERM type): a. A laboratory scale(2.5 liter) cylindrical vessel; b. A bench scale (8 liter) wide vessel. Z. mobilis cultures consumed 89–96% of the cane sucrose, converting it to ethanol by 90–97% of the theoretical yield in the laboratory scale fermentor and by 83–90% in the bench scale fermentor culture. Comparative Saccharomyces spp. cultures in laboratory fermentor consumed 96–98% of the cane sucrose, with ethanol conversion of only 75–79% of the theoretical yield.These preliminary results indicated that sucrose in agricultural size sugar cane chips was ethanol fermentable as compared to small size sugar cane chips or to sugar cane juice. Z. mobilis CP4 cultures converted sucrose more efficiently to ethanol than Saccharomyces spp. as shown in the laboratory scale fermentor studies.The ethanol yields in a wide bench scale fermentor cultures were slightly lower than in a laboratory fermentor.     

Preparation of lactose free milk by fermentation using immobilizedSaccharomyces fragilis

Summary Saccharomyces fragilis cells (40% w/v) were immobilized in 2% Ca-alginate and were used in a batch process for the removal of lactose from milk by fermentation. Immobilized cells (10 g) could completely desugarate 100 mL of milk in 3.5 h. The immobilized preparation was used repeatedly in 15 batches without decrease in the activity.     

The isomaltulose synthesising enzyme ofSerratia plymuthica

Summary An intracellular enzyme was located inSerratia plymuthica which produced isomaltulose from sucrose. The enzyme was purified giving a preparation with a specific activity of 1,285. It has pH and temperature optima of 6.0 and 30°C, respectively. The enzyme was stable retaining 100% activity after 2 weeks at 30°C. It had an isoelectric point at pH 9.0, a Mr of 79,500 and the Km for sucrose was 65.3mM. The enzyme converted 40% (w/v) sucrose to isomaltulose with an efficiency of 87%.     

Inhibition of psychrotrophic bacteria in raw milk by immobilized lactic acid bacteria

Summary Cells ofLactococcus lactis orLactobacillus helveticus were immobilized in calcium-alginate beads, added to raw milk, and incubated 48 h at 7°C. The addition of 2.7×10⁷ immobilizedLc.lactis or 13×10⁷ immobilizedLb. helveticus cells per mL reduced the development of the psychrotrophic bacteria of raw milk by approximately 50%. The pH of the raw milk dropped 0.10 to 0.22 units under these conditions. Periodic agitation of the seeded raw milk increased the inhibitory activity of the immobilized lactic acid bacteria (LAB). Free LAB cells in the system were only of 0.5% of total LAB. The use of immobilized LAB to inhibit psychrotrophic bacteria might be extended to raw milks destined to the manufacture of non-fermented dairy products.