Development and characterization of a lux-modified 2,4-dichlorophenol-degrading Burkholderia sp. RASC

lux -marked biosensors for assessing the toxicity and bioremediation potential of polluted environments may complement traditional chemical techniques. lux CDABE genes were introduced into the chromosome of the 2,4-dichlorophenol (2,4-DCP)-mineralizing bacterium, Burkholderia sp. RASC c2, by biparental mating using the Tn 4431 system. Experiments revealed that light output was constitutive and related to cell biomass concentration during exponential growth. The transposon insertion was stable and did not interrupt 2,4-DCP-degradative genes, and expression of lux CDABE did not constitute a metabolic burden to the cell. A bioluminescence response was detectable at sublethal 2,4-DCP concentrations: at < 10.26 μg ml⁻¹, bioluminescence was stimulated (e.g. 218% of control), but at concentrations > 60 μg ml⁻¹ it declined to < 1%. Investigating the effect of [14C]-2,4-DCP concentration on the evolution of ¹⁴CO₂ revealed that, for initial concentrations of 2.5–25 μg ml⁻¹, ≈55% of the added ¹⁴C was mineralized after 24 h compared with < 1% at 50 and 100 μg ml⁻¹. Inhibition of 2,4-DCP mineralization between 25 and 50 μg ml⁻¹ corresponded well to the EC₅₀ value (33.83 μg ml⁻¹) obtained from bioluminescence inhibition studies. lux -marked RASC c2 may therefore be used as a functionally (i.e. 2,4-DCP degrader) and environmentally relevant biosensor of toxicity and biodegradation inhibition.     

Response surface methodology to optimize the nutritional parameters for enhanced production of jasmonic acid by Lasiodiplodia theobromae

Aims:  To find out the cumulative effect of the nutritional parameters and to enhance the production of jasmonic acid (JA) in static fermentation by Lasiodiplodia theobromae using response surface methodology (RSM).
Method and Results:  Malt extract, sucrose, NaNO₃ and MgSO₄.7H₂O were analysed by a 30-trial central composite design using RSM for optimizing their concentrations in the medium and the effect of their mutual interaction on JA production. Sucrose and NaNO₃ were found highly significant in influencing the JA production. Malt extract and MgSO₄.7H₂O showed an effect on the JA production in interaction with other variables. When the optimum values of the parameters obtained through RSM (19·95 g l⁻¹ malt extract, 50 g l⁻¹ sucrose, 7·5 g l⁻¹ NaNO₃ and 3·51 g l⁻¹ MgSO₄.7H₂O) were applied, 32% increase in JA production (299 mg l⁻¹) was observed in comparison with 225 mg l⁻¹ of JA produced with same media components not analysed by RSM and subsequently validated the statistical model.
Conclusions:  Increase in JA production was achieved by optimizing the nutritional parameters.
Significance and Impact of the Study:  This is the first report of using RSM for optimizing a medium for JA production. It resulted in an increase in JA production without augmentation of costly additives.     

Effects of feeding and induction strategy on the production of BmR1 antigen in recombinant E. coli

Aim:  To investigate the effects of feeding and induction strategies on the production of Bm R1 recombinant antigen.
Methods and Results:  Fed-batch fermentation was studied with respect to the specific growth rate and mode of induction to assess the growth potential of the bacteria in a bioreactor and to produce high yield of Bm R1 recombinant antigen. Cells were grown at a controlled specific growth rate (μ_set) during pre-induction, followed by constant feeding postinduction. The highest biomass (24·3 g l⁻¹) was obtained during fed-batch process operated at μ_set of 0·15 h⁻¹, whereby lower μ_set (0·075 h⁻¹) gave the highest protein production (9·82 mg l⁻¹). The yield of Bm R1 was increased by 1·2-fold upon induction with 1 mmol l⁻¹ IPTG (isopropyl-β- d -thiogalactoside) compared to using 5 mmol l⁻¹ and showed a further 3·5-fold increase when the culture was induced twice at the late log phase.
Conclusions:  Combination of feeding at a lower μ_set and twice induction with 1 mmol l⁻¹ IPTG yielded the best result of all variables tested, promising an improved method for Bm R1 production .
Significance and Impact of the Study:  This method can be used to increase the production scale of the Bm R1 recombinant antigen to meet the increasing demand for Brugia Rapid^™, a commercial diagnostic test for detection of brugian filariasis.     

Influence of phosphorus on biofilm formation in model drinking water distribution systems

Aims:  This study investigated the effects of phosphorus on biofilm formation via annular reactor systems in terms of biofilm cell growth, exopolysaccharide (EPS) production, biofilm structure and cell metabolic potential.
Methods and Results:  Drinking water biofilms were developed in annular reactors with supplement of carbon and different levels of phosphorus. The biofilm formation was monitored over a period of 30 days. Biofilm related parameters were examined by various methods, which included heterotrophic plate count, total carbohydrate content, confocal laser scanning microscopy and GN2 microplate assay. Our results showed that phosphorus addition can promote the biofilm cell growth (cell count increased about 1 log with addition of 30 and 300 μg l⁻¹ of phosphorus). However, the addition of 30 and 300 μg l⁻¹ of phosphorus caused 81% and 77% decrease in EPS production, respectively. The results of biofilm structure analysis showed that the addition of 30 and 300 μg l⁻¹ of phosphorus can induce thicker and less homogeneous biofilms with more biomass. Furthermore, the addition of 30 and 300 μg l⁻¹ of phosphorus dramatically increased the biofilm cell metabolic potential. The addition of 3 μg l⁻¹ of phosphorus was found to have minor effects on the parameters examined.
Conclusions:  The results indicate phosphorus addition to drinking water distribution system (DWDS) has a complicated effect on the biofilm formation.
Significance and Impact of the Study:  As the addition of phosphorus at certain levels can affect the biofilm growth in DWDS, care should be taken when phosphate-based corrosion inhibitors are used in the DWDS.     

Optimization and biochemical characterization of a bacteriocin from a newly isolated Bacillus subtilis strain 14B for biocontrol of Agrobacterium spp. strains

Aims:  The identification of a new compound active against Agrobacterium tumefaciens .
Methods and Results:  The culture conditions of a newly isolated Bacillus subtilis strain, designed 14B, were optimized, as a first step, to produce its bacteriocin (termed Bac 14B) for the biocontrol of Agrobacterium spp., the causal agents of the crown gall disease. Bac 14B was then partially purified and biochemically characterized. Bacillus subtilis 14B was observed to produce an antibacterial compound having a protinaceous nature. As estimated by sodium dodecyl sulfate-polyacrilamide gel electrophoresis (SDS-PAGE), the semi-purified bacteriocin substance was found to be a monomeric protein with a molecular weight of 21 kDa. While the latter's antimicrobial activity was completely stable during exposure to a temperature range of up to 100°C for 2 h, its initial activity was totally lost at 121°C for 20 min. The maximum bacteriocin production (4096 AU ml⁻¹) was recorded after 96 h-incubation in an optimized Luria Bertani medium supplemented with 10 g l⁻¹ glucose, 15 g l⁻¹ K₂HPO₄ and 5 g l⁻¹ MgSO₄ 7H₂O at 30°C in a shaking flask culture. Interestingly, the B. subtilis 14B culture supernatant that contained the bacteriocin under study was proved efficient in reducing both the percentage of galled plants and the number of galls in tomato.
Conclusion:  The findings revealed that B. subtilis 14B and its bacteriocin are efficient in reducing the percentage of infections in plants caused by Ag. tumefaciens .
Significance and Impact of the Study:  The results could be useful for the nurserymen who are particularly interested in the biocontrol of the crown gall disease.     

In vitro efficacy of nisin Z against Candida albicans adhesion and transition following contact with normal human gingival cells

Aim:  To investigate the nisin Z innocuity using normal human gingival fibroblast and epithelial cell cultures, and its synergistic effect with these gingival cells against Candida albicans adhesion and transition from blastospore to hyphal form.
Methods and Results:  Cells were cultured to 80% confluence and infected with C. albicans in the absence or presence of various concentrations of nisin Z. Our results indicate that only high concentrations of nisin Z promoted gingival cell detachment and differentiation. Determination of the LD₅₀ showed that the fibroblasts were able to tolerate up to 80  μ g ml⁻¹ for 24 h, dropping thereafter to 62  μ g ml⁻¹ after 72 h of contact, compared to 160  μ g ml⁻¹ after 24 h, and 80  μ g ml⁻¹ after 72 h recorded by the gingival epithelial cells which displayed a greater resistance to nisin Z. The use of nisin Z even at low concentration (25  μ g ml⁻¹) at appropriate concentrations with gingival cells significantly reduced C. albicans adhesion to gingival monolayer cultures and inhibited the yeast's transition.
Conclusion:  These findings show that when used at non-toxic levels for human cells, nisin Z can be effective against C. albicans adhesion and transition and may synergistically interact with gingival cells for an efficient resistance against C. albicans .
Significance and Impact of the Study:  This study suggests the potential usefulness of nisin Z as an antifungal agent, when used in an appropriate range.     

Acrebol, a novel toxic peptaibol produced by an Acremonium exuviarum indoor isolate

Aims:  To identify a toxin and its producer isolated from woody material in a building where the occupants experienced serious ill health symptoms.
Methods and Results:  Hyphal extracts of an indoor fungus, identified as the cycloheximide-tolerant species Acremonium exuviarum , inhibited motility of boar spermatozoa (EC₅₀ 5 ± 2 μg of crude solids ml⁻¹) and caused cytolysis of murine neuroblastoma cells (MNA) and feline fetal lung cells (FL). The responsible substances were purified and identified as two structurally similar, heat-stable, novel, toxic peptaibols, 1726 Da and 1740 Da, respectively, with amino acid sequences of Acetyl-Phe-Iva/Val-Gln-Aib-Ile-Thr-Leu-Aib-Pro-Aib-Gln-Pro-Aib-(X-X-X)-SerOH and Acetyl-Phe-Iva/Val-Gln-Aib-Ile-Thr-Leu-Val-Pro-Aib-Gln-Pro-Aib-(X-X-X)-SerOH. Purified acrebol inhibited motility of boar sperm, depleted ATP half-content in 1 day (EC₅₀ of 0·1 μg ml⁻¹, 60 nmol l⁻¹) depolarised the mitochondria after 2 days, but did not affect the cellular content in NADH. This indicates mitochondrial toxicity. Plate-grown biomass of A. exuviarum BMB4 contained 0·1–1% (w/w) of acrebol, depending on the culture medium.
Conclusions:  Acrebol paralysed the energy generation of mammalian cells suggesting that mitochondria were its target of action.
Significance and Impact of the Study:  Acremonium exuviarum, as an indoor fungus, is potentially hazardous to health because of the toxic peptaibols that it produces.     

Effects of cadmium chloride on the development of rainbow trout Oncorhynchus mykiss early life stages

The sub-chronic (28–56 days) effects of exposure to low concentrations of cadmium (Cd; 0·05, 0·25, 0·50 and 2·50 μg l⁻¹) shortly following fertilization on embryos, larvae and juvenile rainbow trout Oncorhynchus mykiss were examined. Premature hatching occurred at lower concentrations (0·05 and 0·25 μg l⁻¹ Cd), however, delayed hatching was seen in the 2·50 μg l⁻¹ Cd group, with >90% of hatching occurring on the last day of the hatching period. Larval growth was negatively affected by Cd exposure in a concentration-dependent manner. Larvae exposed to 2·50 μg l⁻¹ Cd were 13·9 ± 0·8% shorter in total length ( L _T) and weighed 22·4 ± 3·5% (mean ± s . e .) less than controls at the end of the exposure period. Plasma sex steroid concentrations (oestradiol in juvenile females and 11-ketotestosterone in juvenile males) were elevated (four- to 10-fold over controls) in exposed fish in both males and females, following 28 days of exposure to 0·05, 0·25 and 0·50 μg l⁻¹ Cd, respectively. These results suggest that environmentally realistic concentrations (in the μg l⁻¹ range) of Cd can affect the development of O. mykiss impacting embryos, larvae and juvenile fish.     

The effects of acid and acid/aluminum exposure on circulating plasma cortisol levels and other blood parameters in the rainbow trout, Salmo gairdneri

Softwater (Ca²⁺=50, Na⁺= 50(μequiv. l⁻¹) acclimated rainbow trout were fitted with chronic arterial catheters to allow for repetitive blood sampling. After 48 h recovery they were then exposed to either control (pH 6.5, Al = 0μg l⁻¹), acid (pH 4.8, Al = 0μg l⁻¹) or acid plus aluminum (pH 4.8, A1 = 112 μg l⁻¹) conditions for 72 h. Parameters measured included blood glucose, lactate, haemoglobin, haematocrit and plasma Na⁺, Cl⁻, protein and cortisol.
Exposure to pH 4'8 alone caused no mortality, a moderate ionoregulatory disturbance and a transient elevation in plasma cortisol. All other parameters were not significantly different from controls. Addition of aluminum to this exposure caused 100% mortality with a mean survival time of only 27.0 h. There was a marked decrease in plasma ions, hyperglycemia, lactate accumulation, haemoconcentration, red cell swelling, and a sharp rise in plasma cortisol becoming greatly increased as the fish neared death. The mechanism of toxicity of acute acid/aluminum exposure, the role for cortisol under such conditions, and the validity of cortisol and glucose as indicators of stress in fish are discussed.     

Structural stability of Sclerotium rolfsii ATCC 201126 β-glucan with fermentation time: a chemical, infrared spectroscopic and enzymatic approach

Aims:  Sclerotium rolfsii ATCC 201126 exopolysaccharides (EPSs) recovered at 48 h (EPS I) and 72 h (EPS II) of fermentation, with differences in rheological parameters, hydrogel topography, salt tolerance, antisyneresis, emulsifying and suspending properties, were subjected to a polyphasic characterization in order to detect structural divergences.
Methods and Results:  Fermenter-scale production led to productivity ( P _r) and yield ( Y _P/C) values higher at 48 h ( P _r = 0·542 g l⁻¹ h⁻¹; Y _P/C = 0·74) than at 72 h ( P _r = 0·336 g l⁻¹ h⁻¹; Y _P/C = 0·50). Both EPSs were neutral glucose-homopolysaccharides with a β-(1,3)-glycosidic backbone and single β-(1,6)-glucopyranosyl sidechains regularly attached every three residues in the main chain, as revealed by chemical analyses. The infra-red diagnostic peak at 890 cm⁻¹ confirmed β-glycosidic linkages, while gentiobiose released by β-(1,3)-glucanases confirmed single β-1,6-glycosidic branching for both EPSs.
Conclusions:  The true modular repeating unit of S. rolfsii ATCC 201126 scleroglucan could be resolved. Structural stability was corroborated and no structural differences could be detected as to account for the variations in EPSs behaviour.
Significance and Impact of the Study:  Recovery of S. rolfsii ATCC 201126 scleroglucan at 48 h might be considered based on better fermentation kinetic parameters and no detrimental effects on EPS structural features.     

The role of light and CO2 in optimising the conditions for shoot proliferation of Actinidia deliciosa in vitro

Proliferating cultures of Actinidia deliciosa A. Chev., C. F. Liang and A. R. Ferguson cv. Tomuri (♂) were grown under photosynthetic photon flux density (PPFD) rates ranging from 30 to 250 μmol m⁻² s⁻¹ in order to determine certain physiological parameters in vitro: CO₂ evolution, photosynthesis at three CO₂ atmospheric concentrations (330, 1450 and 4500 μl l⁻¹), fresh and dry matter accumulation and proliferation rate.
A proportional response in dry weight, dry/fresh weight ratios and PPFD was found. The proliferation rate increased up to 120 μmol m⁻² s⁻¹ but decreased at higher rates. At the highest PPFD, the CO² released from cultures and accumulated in the vessels reached 200 μl l⁻¹ of; at the lowest rate the CO₂ concentration reached 10500 μl l⁻¹ after 28 days of culture. The photosynthetic rate at 1450 and 4500 μl l⁻¹ of CO₂ was nearly 4 times higher than at the lowest concentration tested.     

Intraspecific variation in the response of rice (Oryza sativa) to increased CO2– photosynthetic, biomass and reproductive characteristics

Two rice ( Oryza sativa L.) cultivars of contrasting morphologies, IR-36 and Fujiyama-5, were exposed to ambient (360 μl l⁻¹) and ambient plus 300 μl l⁻¹ CO₂ from time of emergence until ca 50% grain fill at the Duke University Phytotron, Durham, North Carolina. Exposure to increased CO₂ resulted in about a 50% increase in the photosynthetic rate for both cultivars and photosynthetic enhancement was still evident after 3 months of exposure to a high CO₂ environment. The photosynthetic response at 5% CO₂ and the response of CO₂ assimilation (A) to internal CO₂ (C_i) suggest a reallocation of biochemical resources from RuBP carboxylation to RuBP regeneration. Increases in total plant biomass at elevated CO₂ were approximately the same in both cultivars, although differences in allocation patterns were noted in root/shoot ratio. Differences in reproductive characteristics were also observed between cultivars at an elevated CO₂ environment with a significant increase in harvest index for IR-36 but not for Fujiyama-5. Changes in carbon allocation in reproduction between these two cultivars suggest that lines of rice could be identified that would maximize reproductive output in a future high CO₂ environment.     

Pathogenesis-related protein b1' in plants and in cell suspension cultures of Nicotiana glutinosa Nicotiana debneyi and an amphidiploid cross (N. glutinosa×N. debneyi)

The expression of PR-protein b₁' in plants and cell suspension cultures of Nicotiana glutinosa L., Nicotiana debneyi Domin, and an amphidiploid cross of these two species, a hybrid, has been investigated. An enzyme linked immunosorbent assay has been employed to determine the concentration of PR-protein b₁' in extracts. The PR-Protein b₁' was constitutively produced in intact plants of the hybrid (around 25 μg g⁻¹ leaf tissue), while only trace amounts of the protein (< 50 ng g⁻¹ leaf tissue) were found in plants of the two parents. In suspension culture, the concentrations of PR-protein b₁' were 8, 0.4 and less than 0.1 mg l⁻¹ medium for the hybrid. N. debneyi and N. glutinosa , respectively. Only trace amounts of the protein were found in extracts from cells. Seven days after infection by tobacco mosaic virus (TMV) the concentration of PR-protein b₁' in leaves of N. glutinosa was 22.5 μg g⁻¹ leaf tissue. In N. debneyi and the hybrid a relatively limited induction of PR-protein b₁' by TMV was observed. The influence of various phenoxyacetic acids on the expression of PR-protein b₁' in the 3 cell cultures has been investigated. Cultures of N. glutinosa responded to treatments with 2,4-D and 2,4,5-T while cultures of N. debneyi and the hybrid were essentially unaffected. In the former case a concentration of 5–10 mg l⁻¹ 2,4,5-T was optimal and cells were most responsive to the treatment 4 days after subcultivation. The concentration of PR-protein b₁' in elicited cell cultures of N. glutinosa was 2 to 4 mg l⁻¹ medium.     

A potent anti-oxidant property: fluorescent recombinant α-phycocyanin of Spirulina

Aims:  To express and product a fluorescent antioxidant holo-α-phycocyanin (PC) of Spirulina platensis ( Sp ) with His-tag (rHHPC; recombinant holo-α-phycocyaninof Spirulina platensis with His-tag) in 5-l bench scale.
Methods and Results:  A vector harbouring two cassettes was constructed: cpcA along with cpcE - cpcF in one cassette; ho1 - pcyA in the other cassette. Lyases CpcE/F of Synechocystis sp. PCC6803 ( S6 ) could catalyse the 82 site Cys in apo-α-PC of Sp linking with bilin chromophores, and rHHPC was biosynthesized in Escherichia coli BL21. The constant feeding mode was adopted, and transformant reached the biomass of rHHPC up to 0·55 g l⁻¹ broth in 5-litre bench scale. rHHPC was purified by Ni²⁺ affinity column conveniently. The absorbance and the fluorescence emission spectra of rHHPC had λ_max at 621 and 650 nm, respectively. The IC₅₀ values of rHHPC were 277·5 ± 25·8 μ g ml⁻¹ against hydroxyl radicals and 20·8 ± 2·2  μ g ml⁻¹ against peroxyl radicals.
Conclusions:  Combinational biosynthesis of rHHPC was feasible, and the constant feeding mode was adopted to produce good yields of rHHPC. Fluorescent rHHPC with several unique qualitative and quantitative features was effective on scavenging hydroxyl and peroxyl radicals.
Significance and impact of the study:  A potent antioxidant rHHPC was co-expressed, produced and characterized for nutritional and pharmacological values, which would help to develop phycobiliproteins' applications in their fluorescent and biological activities.     

Fed-batch culture of Candida guilliermondii FTI 20037 for xylitol production from sugar cane bagasse hydrolysate

A fed-batch culture system was used to study xylitol production by Candida guilliermondii FTI 20037 in a synthetic and a sugar cane bagasse hydrolysate medium. The values achieved for xylitol yield and volumetric productivity were, respectively, 0 · 84 g g⁻¹ and 0 · 64 g l⁻¹ h⁻¹ using the synthetic medium and 0 · 78 g g⁻¹ and 0 · 62 g l⁻¹ h⁻¹ using the hydrolysate medium.     

Net CO2 exchange of Pinus taeda shoots exposed to variable ozone levels and rain chemistries in field and laboratory settings

Net CO₂ exchange rates (CERs) were measured in seedlings of two loblotly pine ( Pinus taeda L.) families following 6- or 13-week exposures to ozone (charcoalfiltered or ambient air + O₃) and acid rain treatments (pH 3.3, 4.5 and 5.2). Ozone exposures (14 or 170 nl l⁻¹) were made in open-top chambers, and in continously stirred tank reactors (14, 160 or 320 nl l⁻¹) located in the field and laboratory, respectively. The CERs of whole shoots were measured in an open infrared gas analysis system at 6 levels of photosynthetic photon flux density (0, 33, 60, 410, 800 and 1660 μmol m⁻² s⁻¹). Treatment effects were not consistent between field- and laboratory-exposed seedlings. Ozone-treated field seedlings exhibited statistically significant reductions in light-saturated CER of 12.5 and 25% when measured at 6 and 13 weeks, respectively. Laboratory seedlings exhibited mixed responses to O₃, with one family showing reduced CER only after 6 weeks of O₃ exposure and the other only after 13 weeks (O₃ >160 nl l⁻¹ for both). After 13 weeks of exposure, pH 3.3, and 4.5 rain treatments enhanced light-saturated CER by an average of 52% over that observed in seedlings exposed to the pH 5.2 treatment. Enhanced CERs due to acid rain were of the same magnitude (3–5 μmol CO₂g⁻¹ s⁻¹) as ozone-induced CER reductions. No differences in dark respiration were detected between treatments. Although ozone and acid rain treatments altered seedling CER, the differences were not translated into altered final plant dry weights over the 13-week exposure period.     

Itaconic acid production by Aspergillus terreus on raw starchy materials

Starchy materials such as corn starch, soft wheat flour, potato flour, cassava flour, sorghum starch, sweet potato and industrial potato flours, either acid or enzymatically hydrolysed, were used as substrates for itaconic acid production by Aspergillus terreus NRRL 1960. Both production and yield were highest on corn starch (18·4 g l⁻¹ and 34·0%, respectively). The degree of hydrolysis had a great influence on acid production which was highest when corn starch was saccharified at 85 DE (dextrose equivalent). In a 3 litre benchtop fermenter, itaconic acid production and productivity were 19·8 g l⁻¹ and 0·13 g l⁻¹ h⁻¹, respectively.     

Effects of waterborne complexing agents on silver uptake and depuration in rainbow trout

Rainbow trout Oncorhynchus mykiss ( c . 60 g) were exposed for 1 week to 0·1 μM silver as AgNO₃ in ion poor water (Ca c . 150 μM, pH c . 8, water temperature 13° C) with or without waterborne organic matter (27 mg C l⁻¹ as Aldrich humic acid), thiosulphate (5 μM Na₂S₂O₃) or chloride (4 mM KCl). Organic matter decreased Ag accumulation by the gills initially, but did not decrease Ag accumulation by plasma or liver. Thiosulphate decreased the amount of Ag accumulated by the gills for the entire 1 week exposure but had no effect on Ag concentrations in the plasma, liver or bile. Chloride had no effect on Ag uptake in any of the tissues examined. All three complexing agents reduced the decreases in plasma Na and Cl concentrations caused by Ag. To study the effects of waterborne complexing agents on Ag depuration, rainbow trout were exposed to 0·1 μM AgNO₃ for 1 week then placed for 8 days in Ag‐free, ion poor water with or without waterborne organic matter (55 mg C l⁻¹) or thiosulphate (5 μM). These complexing agents did not alter depuration of Ag from the gills, plasma, liver or bile. Thus, once Ag has entered a fish, subsequent elimination of internal Ag is not affected by external complexing agents.     

The content of prostaglandins and their precursors in Mortierella and Cunninghamella species

Five strains of filamentous fungi belonging to the genera Mortierella and Cunninghamella were examined for the content of dihomo-γ-linolenic, arachidonic, eicosapentaenoic acids and prostaglandins (type E₂ and F _2α). Prostaglandins were detected using an ELISA method in mycelia of all tested strains (range 50–4800 ng g⁻¹ of PGE₂ and 6–30 ng g⁻¹ of PG F _2α). Several micro-organisms also produced prostaglandins in the culture medium (2·2–137·6 μg l⁻¹ for PGE₂ and 0·4–7·8 μg l⁻¹ for PG F _2α).     

Bactericidal activity of catechin-copper (II) complexes on Escherichia coli ATCC11775 in the absence of hydrogen peroxide

Washed Escherichia coli ATCC11775 cells were killed by (–)-epigallocatechin (EGC) in the presence of a non- lethal concentration of Cu²⁺ (1 μmol l⁻¹) without additional H₂O₂, but not by (–)-epicatechin (EC). EGC alone (< 0·1 mmol l⁻¹) did not reduce the viability of the cells. The survival curve obtained in the presence of EGC and Cu²⁺ was similar to that obtained in the presence of (–)-adrenaline (EN) and Cu²⁺.