Promotion of indole alkaloid production in Catharanthus roseus cell cultures by rare earth elements

Production of the indole alkaloids, ajmalicine or catharanthine, in cell suspension cultures of Catharanthus roseus was enhanced by cerium (CeO₂ and CeCl₃), yttrium (Y₂O₃) and neodymium (NdCl₃). The yield of ajmalicine in these treated-cultures reached 51 mg l^–1 (CeO₂), 40 mg l^–1 (CeCl₃), 41 mg l^–1 (Y₂O₃) and 49 mg l^–1 (NdCl₃) while catharanthine production reached to 36 mg l^–1 (CeO₂) and 31 mg l^–1 (CeCl₃). A major portion of increased alkaloids was released into medium in these treatments. But Sm₂O₃, SmCl₃, La₂O₃, LaCl₃, complex of chromium (III)-titanium (IV) and NaSeO₄ treatments had little effect on alkaloid production of C. roseus cell cultures.     

Processing of leaf matter by lake-dwelling shredders at low oxygen concentrations

Organic sediments in freshwaters are regularly subject to low concentrations of oxygen. The ability of detritivores to sustain their feeding in such conditions should therefore be of importance for the decomposition process. In the present study, aquaria were used to determine processing rates of five lake-dwelling shredders at three different oxygen concentrations; normoxic (9 mg O₂ l^–1) and two levels of hypoxia (1 and 2 mg O₂ l^–1). Discs of alder leaves (Alnus glutinosa (L.)) were used as food. Four species of caddisfly larvae (Trichoptera Limnephilidae) and the isopod, Asellus aquaticus (L.) were compared in the experiments. Significant differences in processing rates per g animal biomass were found both at normoxia and 2 mg oxygen l^–1. At l mg O₂ l^–1 none of the invertebrates fed on leaf discs. The caddisfly larvae Halesus radiatus (Curtis), being one of the two most efficient shredders at normoxia, did not feed at 2 mg oxygen l^–1. The other species fed at rates 15–50 of that at normoxia. The least efficient shredder at normoxia, A. aquaticus was similar to two of the trichopterans at 2 mg O₂ l^–1. This study shows that the importance of specific shredder species may shift in case of hypoxia. Species-specific traits regarding oxygen sensitivity may also be influential for distribution patterns of shredder species both within and between lakes.     

Energy metabolism of Chironomus anthracinus (Diptera: Chironomidae) from the profundal zone of Lake Esrom,Denmark, as a function of body size,temperature and oxygen concentration

The profundal zone of Lake Esrom, Denmark has a dense population of Chironomus anthracinus, which survives 2–4 months of oxygen depletion each summer during stratification. The metabolism of 3rd and 4th instar larvae was examined in regard to variation in biomass and temperature. Respiration at air saturation was described by a curvilinear multiple regression relating oxygen consumption to individual AFDW and temperature. At 10 °C and varying oxygen regimes the O₂ consumption and CO₂ production of 4th instar larvae were almost unaltered from saturation to about 3 mg O₂ l^–1, but decreased steeply below this level. The respiratory quotient increased from 0.82 at saturation to about 3.4 at oxygen concentrations near 0.5 mg O₂ l^–1. This implied a shift from aerobic to partially anaerobic metabolism. At 0.5 mg O₂ l^–1 the total energy production equalled 20% of the rate at saturation of which more than one third was accounted for by anaerobic degradation of glycogen. This corresponded to a daily loss of 12 µg mg AFDW^–1 or approximately 5% of the body reserves. At unchanged metabolic rate the glycogen store would last three weeks, but long term oxygen deficiency causes a further suppression of the energy metabolism in C. anthracinus.     

Microbial treatment of a synthetic sour brine

Summary The ability of the chemoautotroph and facultative anaerobeThiobacillus denitrificans to deodorize and detoxify an oil-field-produced water containing sulphides was evaluated under simulated field conditions. A sulphide-tolerant strain ofT. denitrificans was used to remove inorganic sulphide from a synthetic sour brine containing 4000 mg L^–1 total dissolved solids (TDS) and 100 mg L^–1 sulphide. The sour brine was treated continuously in a rectangular plugflow reactor which approximated the scaled dimensions of an existing field detention pond. The head space of the reactor was purged with N₂ in order to capture H₂S off-gases in a zinc acetate trap. Brine was fed to the reactor continuously for 90 days at rates corresponding to residence times of 0.17–6 days. Temperature and pH ranged from 22 to 40.5°C and 7.5 to 8.8, respectively. The start-up biomass concentration was approximately 100 mg L^–1 (by dry weight). No. additionalT. denitrificans biomass was added to the reactor after start-up. At residence times of 0.3 days and greater inorganic sulphide was undetectable in the effuent. No H₂S was detected in the outlet gas or the zinc acetate trap. Approximately 80% of the sulphide feed was oxidized to sulphate and removed from the reactor in the liquid effluent. The remainder was partially oxidized to elemental sulphur which was retained in the reactor. It is suggested that oxidation of inorganic sulphides byT. denitrificans represents a viable process concept for the treatment of sour water co-produced with oil and gas.     

ε-Caprolactam-degradation by Alcaligenes faecalis for bioremediation of wastewater of a nylon-6 production plant

Alcaligenes faecalis G utilized 95–97% of 5–15 g -caprolactam l^–1 in 24–48 h over a pH range of 6–8.5 and at 23–40 °C, without complex nutrient requirement. In the absence of KH₂PO₄ and K₂HPO₄/MgSO₄ in the medium, only 7.6% and 0.2% of 10 g caprolactam l^–1 was utilized, respectively. The chemical oxygen demand (COD) of the wastewater of nylon-6 plant was mainly due to its caprolactam content. A. faecalis G decreased the caprolactam content and COD of the wastewater by 80–90% of the original in spite of the wastewater having higher caprolactam content (3600 mg l^–1) and COD (7700 mg l^–1) than those of any of the previous reports.     

Cell death unlikely contributes to taxol production in fungal elicitor-induced cell suspension cultures of Taxus chinensis

Cell suspension cultures ofTaxus chinensis, with 20, 40 and 100 mg fungal elicitor l^–1 from Aspergillus niger, underwent rapid cell death after 24 h, which was about 2, 3.7 and 5-fold of that of the control. At the same time, Taxol production was increased, respectively, to about 5, 8 and 3-fold of that of the control. Inhibition of phenolics biosynthesis resulted in a 150% increase in cell death but a 54% decrease in Taxol production compared with 40 mg elicitor l^–1 alone. O₂-free N₂ inhibited cell death but had little effect on Taxol production as induced by 40 mg fungal elicitor l^–1.     

Sequential liquid-liquid extraction of d-amino acid oxidase from Trigonopsis variabilis

A method for isolation of d-amino acid oxidase (DAAO) from disrupted Trigonopsis variabilis cells has been developed. In an aqueous two-phase system consisting of PEG6000 (220 g l^–1), potassium phosphate (110 g l^–1, K₂HPO₄ + KH₂PO₄ = 10.1:1, mol mol^–1) and dl-methionine (11 g l^–1), the major portion of cellular proteins (87%) was partitioned into the salt phase. By sequential extraction, 48% of DAAO was recovered in PEG phase, giving a yield of 211 U mg protein^–1.     

Candida guilliermondii grows on rare pentoses – implications for production of pure xylitol

Feeding sucrose at 20 g l^–1 on day 16 gave maximum paclitaxel production at 10 mg l^–1 when Taxus chinensis in 5 l bioreactors. Paclitaxel accumulation was doubled by the cultivation of cells initially with dissolved O₂ tension at 60% for 20 days followed by being at 20% for another 12 days in the bioreactor. Combination of these two strategies gave maximum paclitaxel production of 19 mg l^–1 after 32 days.     

Efficient GA3-assisted plant regeneration from cell suspensions of three grape genotypes via somatic embryogenesis

Petioles from in vitro grown plants of interspecific grapevine hybrids cvs `Bianca', `Podarok Magaracha' and `Intervitis Magaracha' were cultured on solid NN medium supplemented with 2,4-D and BA at various concentrations. The callus developed was cultured in liquid NN medium supplemented with 0.5 mg l<sup>–1</sup> BA to induce formation of somatic embryos. Somatic embryos of globular and heart-stage developed in suspensions of `Podarok Magaracha' and `Intervitis Magaracha'. In contrast, `Bianca' did not undergo embryogenesis beyond globular stage. This made it necessary to perform subculture of the suspensions to HTE liquid medium supplemented with 0.2 mg l^–1 BA for the development of globular embryos into heart stage. Heart-stage embryos developed into torpedo-stage after subculturing suspensions of all three cultivars to liquid HTE medium supplemented with 0.1 mg l^–1 IAA and 30 mg l^–1 sodium hummate. Torpedo-stage embryo suspensions were subcultured in liquid HTE medium supplemented with 0.5 mg l^–1 BA, 0.5 mg l^–1 GA₃ and 0.5 mg l^–1 GA₃ + 0.2 mg l^–1 BA. After 12 days of incubation, plantlets were cultured on solid M2MS medium: without growth regulators and with 0.5 mg l^–1 BA. Plantlets that developed in liquid HTE media with 0.5 mg l^–1 GA₃ or 0.5 mg l^–1 GA₃ + 0.2 mg l^–1 BA produced 82–90% shoots on solid M2MS medium with 0.5 mg l^–1 BA after 50 days of culture.     

Development of a responsive methanol sensor and its application in Pichia pastoris fermentation

A methanol sensor was developed with response time less than 2 min. It was unaffected by the dissolved O₂ concentration, agitation speed or pH value. When the sensor was used to monitor the methanol concentration on-line during hirudin production by recombinant Pichia pastoris, the cell dry weight was up to 155 g l^–1, and hirudin was 1.4 g l^–1.     

Mixotrophic growth ofChlorella sorokiniana in outdoor enclosed photobioreactor

Chlorella sorokiniana was cultured in heterotrophic or mixotrophic mode in outdoor enclosed tubular photobioreactor. The culture temperature was maintained at 32–35 °C. At night, theChlorella culture grew heterotrophically, and 0.1 M glucose was completely consumed. The biomass growth yield of glucose was 0.35 ± 0.001 g-biomass g-glucose^–1. During the day, the algal culture grew mixotrophically and the biomass growth yield was 0.49 g-biomass g-glucose^–1 in low density culture (initial biomass concentration, X_o = 2 g l^–1), 0.56 g-biomass g-glucose^–1 in medium density culture (X_o = 4 g l^–1) and 0.46 g-biomass g-glucose^–1 in high density culture (X_o = 7 g l^–1). The daily area productivity of the culture, with X_o = 4 g l^–1 corresponded to 127 g-biomass m^–2 d^–1 during the day and 79 g-biomass m^–2 d^–1 during the night. In all the cultures, the dissolved O₂ concentration increased in the morning, reached the maximum value at noon, and then decreased in the afternoon. The dissolved CO₂ concentration remained at 3 mBar in the morning and increased in the afternoon. Glycolate was not found to accumulate in culture medium.     

Metabolism of 1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene by Alcaligenes denitrificans

Metabolism of 1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene (DDE), a persistent metabolite of 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT), by an Alcaligenes denitrificans was optimal under `non-shaking' conditions, was accelerated by adding 1 g glucose l^–1, and inhibited by 1 g sodium acetate l^–1 or 1 g sodium succinate l^–1. Addition of biphenyl, in the vapor form, to the reaction mixture did not enhance DDE metabolism. During the reaction, accumulation of conventional metabolites, 1-chloro-2,2-bis(4-chlorophenyl)ethylene (DDMU) and 4-chlorobenzoate, was not observed.     

The Bioutilization of Thiodiglycol (a Detoxication Product of Mustard Gas): Isolation of Degrading Strains and Investigation of Degradation Conditions

The Alcaligenes xylosoxydans subsp.denitrificans strain TD1 capable of degrading thiodiglycol (TDG), a product of mustard gas hydrolysis, was isolated from soil contaminated with breakdown products of this chemical warfare agent. The selected stable variant of TD1 (strain TD2) can grow on TDG with a lag phase of 4–8 h and a specific growth rate of 0.04–0.045 h^–1. Optimal conditions for the biodegradation of TDG (pH, the concentration of TDG in the medium, and specific substrate loading) were determined. TDG was found to be degraded with the formation of diglycolsulfoxide and thiodiglycolic acid as intermediate products. The data obtained can be used to develop approaches to the bioremediation of mustard gas–contaminated soils.     

Reducing by-product formation in L-lactic acid fermentation by Rhizopus oryzae

During L-lactic acid fermentation by Rhizopus oryzae, increasing the phosphate level in the fermentation medium from 0.1 g l^–1 to 0.6 g l^–1 KH₂PO₄ reduced the maximal concentration of L-lactic acid and fumaric acid from 85 g l^–1 to 71 g l^–1 and from 1.36 g l^–1 to 0.18 g l^–1, respectively; and it decreased the fermentation time from 72 h to 52 h. Phosphate at 0.40 g l^–1 KH₂PO₄ was suitable for both minimizing fumaric acid accumulation and benefiting L-lactic acid production.     

Evaluation of the environmental conditions for the continuous production of lignin peroxidase by Phanerochaete Chrysosporium in fixed-bed bioreactors

A new system to produce lignin peroxidase (LiP) continuously by Phanerochaete chrysosporium is described. A fixed-bed bioreactor with a pulsing device was used as the optimal bioreactor configuration. Addition of veratryl alcohol (1 mM), tryptophan (1 mM), no Mn²⁺ addition, low glucose addition rate (60–70 mg l^–1 h) and an atmosphere of O₂ gave maximum LiP activities of 700 U l^–1, which are higher than those previously reported.     

Development of dependence on aerial respiration in Polypterus senegalus (Cuvier)

The respiratory behaviour and partitioning of O₂ uptake between air and water were investigated in Polypterus genegalus using continuous-flow and two-phase respirometers and lung gas replacement techniques P. senegalus rarely resorts to aerial respiration under normal conditions. Partitioning of O₂ consumption depends on the activity and age of fish and the availability of aquatic oxygen. Immature fish (12–22 g) cannot utilize aerial O₂ but older fish exhibit age-dependent reliance on aerial respiration in hypoxic and hypercarbic waters. Pulmonary respiration accounts for 50% of the total requirement at aquatic O₂ concentrations of about 3.5 mg · l^–1 (or CO₂ of about 5%) and fish rely exclusively on aerial respiration at O₂ concentrations of less than 2.5 mg · l^–1. Branchial respiration is initially stimulated by hypercarbia (CO₂: 0.5–0.8%) but increased hypercarbia (CO₂ – 1%) greatly depresses (by over 90%) brancial respiration and initiates (CO₂: 0.5%) and sustains pulmonary respiration.     

Culture conditions of tannase production by Lactobacillus plantarum

Lactobacillus plantarum produced an extracellular tannase after 24 h growth on minimal medium of amino acids containing 2 g tannic acid l^–1. Enzyme production (6 U ml^–1) was optimal at 37 °C and pH 6 with 2 g glucose l^–1 and 7 g tannic acid l^–1 in absence of O₂.     

Production of poly(3-hydroxybutyrate) from whey by cell recycle fed-batch culture of recombinant Escherichia coli

A new fermentation strategy using cell recycle membrane system was developed for the efficient production of poly(3-hydroxybutyrate) (PHB) from whey by recombinant Escherichia coli strain CGSC 4401 harboring the Alcaligenes latus polyhydroxyalkanoate (PHA) biosynthesis genes. By cell recycle, fed-batch cultivation employing an external membrane module, the working volume of fermentation could be constantly maintained at 2.3 l. The final cell concentration, PHB concentration and PHB content of 194 g l^–1, 168 g l^–1 and 87%, respectively, were obtained in 36.5 h by the pH-stat cell recycle fed-batch culture using whey solution concentrated to contain 280 g lactose l^–1 as a feeding solution, resulting in a high productivity of 4.6 g PHB l^–1 h^–1.     

Food consumption of Sarotherodon mossambicus (Trewaves) exposed to sublethal concentration of diammonium phosphate

S. mossambicus was exposed to toxic and sublethal concentrations of the fertilizer diammonium phosphate (0.2 to 1.0 g l^–1). Mortality, food utilization and growth were studied. At a concentration of 0.6 g l^–1 DAP, 100% mortality was observed within 96 h; no mortality occurred at 0.5 g l^–1; LC50 was 0.55 g l^–1. Rearing the fish in increasing sublethal concentrations of DAP, it was found that the feeding rate decreased from 25.4 mg g^–1 fish^–1 d^–1 (fish reared in DAP-free water) to 10.1 mg g^–1 d^–1 at the highest sublethal concentration (0.5 g l^–1). Growth rate was drastically reduced. At high sublethal concentrations of DAP, the fish lost reserve energy, in addition to the energy obtained from food intake for survival, as a result of increased swimming activity and opercular beats.     

Glucose repression of xylitol production in Candida tropicalis mixed-sugar fermentations

Glucose repressed xylose utilization inCandida tropicalis pre-grown on xylose until glucose reached approximately 0–5 g l^–1. In fermentations consisting of xylose (93 g l^–1) and glucose (47 g l^–1), xylitol was produced with a yield of 0.65 g g^–1 and a specific rate of 0.09 g g^–1 h^–1, and high concentrations of ethanol were also produced (25 g l^–1). If the initial glucose was decreased to 8 g l^–1, the xylitol yield (0.79 g g^–1) and specific rate (0.24 g g^–1 h^–1) increased with little ethanol formation (<5 g l^–1). To minimize glucose repression, batch fermentations were performed using an aerobic, glucose growth phase followed by xylitol production. Xylitol was produced under O₂ limited and anaerobic conditions, but the specific production rate was higher under O₂ limited conditions (0.1–0.4 vs. 0.03 g g^–1 h^–1). On-line analysis of the respiratory quotient defined the time of xylose reductase induction.