Effect of media composition on the production of extracellular amylase from the thermophilic fungusThermomyces lanuginosus

Summary The production of extracellular amylase by the thermophilic fungusThermomyces lanuginosus was studied in shake flask cultures with different carbon sources in the growth medium. Maximum amylase production was obtained with dextran as carbon source. The greatest yield of amylolytic activity was found when low molecular weight dextrans were used as carbon source.     

Foaming and enzyme activity in fungal cultures grown on sugar beet cosette

Summary Enzyme synthesis, foaming behaviour and its effects were studied using two common cellulolytic fungi;Trichoderma reesei andSporotrichum pulverulentum in a medium containing sugar beet cosette as a cellulosic substrate. Cellulase enzyme activities in the culture broth were found to be higher than the enzyme activities in natural and experimentally forced foam layers.     

Mutants ofStreptomyces hygroscopicus deregulated in amylase and α-glucosidase formation

Summary Two mutants, M36 and M39, of turimycin-producingS. hygroscopicus JA 6599/PR1 obtained by directed selection in a chemostat displayed altered pattern of amylase and -glucosidase production as revelaed by both constitutive enzyme formation and higher enzyme levels.     

Limitations on the use of immobilized bacterial biofilms for enzymically-mediated uranyl ion accumulation

Summary A phosphatase-overproducing mutant of a Citrobacter sp. was evaluated in terms of its ability to self-immobilize as a biofilm on reticulated foam supports and to accumulate uranium when retained in a flow-through column. Parallel studies using polyacrylamide gel-immobilized cells suggested decreased substrate was available to cells of the mutant.     

Hybrids between tobacco crown gall cells and normal somatic cells of Atropa belladonna

Protoplast fusion of Nicotiana tabacum (B6S3) crown gall cells and Atropa belladonna leaf mesophyll cells was carried out. Hybrids were selected for their capacity to grow on hormone-free media and to green in light. Shoots incapable of rhizogenesis were regenerated on the same media and grafted onto normal plants of different species. 57 hybrid cell lines differing in their genetic constitution were produced. Analysis of hybrid lines involved the determination of the lysopine dehydrogenase (LpDH) activity and the molecular forms of esterase and amylase, a restriction analysis of chloroplast DNA and a cytogenetic study.Abbreviations LS-H Linsmaier and Skoog (1965) hormone-free medium - LpDH lysopine dehydrogenase     

Role of antimicrobial agents in simultaneous saccharification and fermentation of paddy malt mash to ethanol by mixed cultures of Saccharomyces cerevisiae PH03 and Zymomonas mobilis ZM4

Summary Among various antimicrobial plant extracts, chemicals and antibiotics used for simultaneous saccharification and fermentation, penicillin G prevented contamination and did not inhibit amylase activity and growth of the synergistic co-cultures Saccharomyces cerevisiae PH03 and Zymomonas mobilis ZM4 during a 7-day fermentation of paddy malt (25.0%) mash (18.0% dextrose equivalent) to ethanol at 30°C and pH 5.5. The treatment yielded 10.1% (v/v) ethanol from the mash which was significantly more than that of the boiled and fermented mash (9.3% v/v) and equal to that of the mash boiled and fermented (10 2% v/v) after added amylases treatment. Most of the other compounds (kanamycin, streptomycin, polymyxin, tetracycline) had growth inhibitory effect especially on Z.mobilis.     

Vertical Rotating Immobilized Cell Reactor of the bacteriumZymomonas mobilis for stable long-term continuous ethanol production

Summary Vertical Rotating Immobilized Cell Reactor was designed and built for glucose conversion into ethanol. Immobilized biomass units withZ. mobilis cells attached into polyurethane foam discs were fixed along a rotating shaft inside the bioreactor. The effect of rotation speed on the concentration of immobilized biomass was studied. Stability of the bioreactor over long-term operation was dependent on the concentration of the immobilized biomass. With fermentation carried out at 6 rpm a constant active immobilized cell concentration of only 34.5 g/l was maintained and used to convert up to 140 g glucose/l into more than 70 g ethanol/l with a volumetric ethanol productivity of 63 g/l/h.     

Extracellular maltotetraose-forming amylase ofPseudomonas sp. IMD 353

Summary Pseudomonas sp. IMD 353 produced an extracellular consititutive maltotetraose-forming amylase in a medium containing glucose (or fructose), yeatex and mineral salts. Km values on starch, amylopectin and short chain amylose were 4.0, 2.8 and 3.0 mg/ml, repectively. Sulphydryl reducing agents activated the enzyme considerably, as did Co²⁺ and Mn²⁺.     

Growth of immobilised plant cells in reticulate polyurethane foam matrices

Summary An inoculum of initially freely suspended cell aggregates ofCapsicum frutescens was immobilised in porous polyurethane foam matrices. Subsequent growth and substrate consumption of these immobilised cells in batch culture were measured and compared with those of suspension cultures. The results showed that the maximum specific growth rate of freely suspended cells was slightly higher than that of immobilised cells but the overall growth patterns and final cell yields were similar.     

Ethanol production from sucrose by immobilizedZymomonas mobilis cells in polyurethane foam

Summary The possibility of using polyurethane foam as a support for the immobilization ofZymomonas mobilis cells to carry out sucrose conversion to ethanol was investigated. Sucrose hydrolysis efficiencies of 90% and higher, volumetric reactor productivity of 20 gL^–1h^–1 and final ethanol concentration of 6.3% (v/v) at a dilution rate of 0.4 h^–1 show the good performance of polyurethane foams for whole cell immobilization.     

Improved diosgenin production in Dioscorea deltoidea cell cultures by immobilization in polyurethane foam

Dioscorea deltoidea Wall (Dioscoreaceae) cell cultures were entrapped by passive invasion into reticulate polyurethane foam cubes. Immobilization of cells grown in medium containing 3% sucrose reduced the lag phase in growth and thereby reduced the time required to reach maximum diosgenin concentration by 36% compared to cells in suspension culture. Immobilization also increased the total diosgenin produced by 40%. Increased efficiency in diosgenin production was greatest in 3% sucrose; higher concentrations inhibited diosgenin production.     

High ethanol yields using Aspergillus oryzae koji and corn media

Summary High ethanol and stillage solids have been achieved using whole corn mashes. Ethanol yields of 14% (v/v) (89.5% of theory) and stillage levels of approximately 23% (w/v) were obtained in 74–90 hours using mild acid pretreatment with Aspergillus oryzae wheat bran koji saccharification. High ethanol yields were also obtained with bacterial amylase, instead of the acid treatment, when the sterilization step was omitted. The implications of ethanol fermentation process modifications are explored.     

A comparison of growth yields obtained fromSchwanniomyces castellii and an alcohol dehydrogenase mutant

Summary The growth yields and the rates of production of -amylase and amyloglucosidase have been compared for the wild strain ofSchwanniomyces castellii and an alcohol dehydrogenase mutant. The loss of fermentative ability in the mutant strain leads to limited but significant increases in biomass yields, and in amylase production.     

Biotransformation of (−)-codeinone to (−)-codeine byPapaver somniferum cells immobilized in reticulate polyurethane foam

Papaver somniferum cells immobilized in reticulate-polyurethane foam biotransformed (–)-codeinone to (–)-codeine. A biotransformation ratio of 79% was found in immobilized cells whereas a ratio of 57% was found in suspended cells. Of the total amount of codeine formed only 12.2% was detected inside the cells, most of the product (87.3%) being released into the medium. When immobilized cells were cultivated in the absence of nitrate, only 40% of the cells remained alive and the biotransformation of codeinone was strongly reduced. When orthophosphate was omitted from the growth medium a bioconversion ratio of 86% was achieved.     

A method for the rapid production of fine plant cell suspension cultures

A method has been devised which allows the rapid production of fine suspension cultures of small aggregate size from suspension cultures of large average aggregate size, such as those of Capsicum frutescens. The method, which uses a Waring blender for aseptic homogenisation of cultures, has also been shown to be effective in rapidly producing suspension cultures from callus cultures. The suspension cultures so produced are particularly useful for immobilisation, such as in porous polyurethane foam matrices.     

Glucose and glycerol repression of α-amylase in Streptomyces kanamyceticus and isolation of deregulated mutants

Summary Glucose and glycerol at concentrations of 2 % negatively affected amylase synthesis in plate and submerged Streptomyces kanamyceticus cultures. This microorganism was insensitive to growth inhibition by glucose analogs and deregulated mutants were identified by a clearing zone around colonies grown on starch and glycerol or glucose, and selected. Three kinds of mutants were obtained: one insensitive to glucose (Mutant 41), another insensitive to glycerol repression (Mutant E) and the last (Mutant 29) an amylase-hyperproducing mutant, albeit regulated by glucose or glycerol like the wild type. The levels of glucokinase, an enzyme involved in catabolite regulation of Enterobacteria, were determined and results showed no differences between the parental strain and the mutants.     

High activity xylanase from thermotolerantStreptomyces T7: Cultural conditions and enzyme properties

Summary A thermotolerantStreptomyces T₇ produced 70–72 U/ml of extracellular xylanase activity when grown at 50°C in submerged culture, in à medium containing 5% wheat bran as a carbon source. Among the various sugars tested, maltose showed the highest activity of 8 U/ml. Pure xylan was less effective as an inducer as compared to wheat bran. Ammonium sulphate at a concentration of 0.7% was found to be optimum for maximum yield of the enzyme. The optimum period and pH for maximum production were 72th and 7.0, respectively. The culture filtrate was devoid of amylase, cellulase and B-xylosidase activity. The xylanase was exceptionally stable and did not show any loss in activity after storage at 50°C at pH 5.0 for 6 days.     

Instability of lactose and citrate metabolism of Leuconostoc strains

Summary The instability of Lac⁺ and Cit⁺ phenotypes was investigated inLeuconostoc mesenteroides subsp.cremoris ATCC 19245 and in four strains ofLeuconostoc mesenteroides subsp.dextranicum. The two phenotypes were linked respectively to a 14 Mdal and a 34 Mdal plasmid in Leuconostoc mesenteroides subsp.cremoris ATCC 19245. InLeuconostoc mesenteroides subsp.dextranicum the character Lac⁺ was linked to a 28 Mdal plasmid, while the Cit⁺ phenotype was stable.     

Non-polluting wood and pulp delignification: Biomimetic ligninase system

Summary We report the delignification ofPinus radiata D Don,Eucalyptus globulus andEucalyptus grandis woods (formic acid treated and untreated) by 2 h treatment with a hemin/hydrogen peroxide system. The untreated chips and sawdust ofE. globulus were 30% and 50% delignified respectively. No significant effects were found forP. radiata sawdust;P. radiata treated chips (organosolv pulp) did not show any further delignification upon hemin/peroxide action, 25% delignification was achieved in untreated chips. In the case ofE. grandis untreated wood the delignification was better in sawdust than in chips, but in smaller percentage than in the otherEucalyptus species. This relation is maintained in substrates, treated with formic acid or untreated. The delignification of chips in both species ofEucalyptus was improved when they were pre-treated with formic acid. The loss of lignin in theE. grandis andE. globulus sawdust (pre-treated with formic acid) was 79% and 75% respectively.     

Partial characterization of anEscherichia coll strain harboring a xylanase encoding plasmid

Summary The plasmid pRH271, harboring a xylanase gene cioned fromBacilius subtilis, has been transferred into a mutant ofE. coli SK2284 which allowed the release of part of the xylanase in the culture supernatant. Kinetic parameters of this recombinantE. coll strain were determined in microscale batch culture with and without the selective pressure of antibiotics. No significant difference in µ_max was observed for the nontransformedE. coli strain when compared to the recombinant strain. However, K₅ values for glucose were two times higher in the case of the recombinant strain. Preliminary study of xylanase production in a large batch farmenter was also described.