Impact of non-selective fungicides on the growth and production of ochratoxin A by Aspergillus ochraceus and A. carbonarius in barley-based medium

The aim of this study was to assess the influence of the non-selective fungicides mancozeb, copper oxychloride, and sulfur on the growth and capability for producing ochratoxin A (OTA) of ochratoxigenic isolates of Aspergillus carbonarius and A. ochraceus in barley-based medium. Lag phases and growth rates were determined for each fungicide at different doses, at 15°C and 25°C and at 0.97?a_w . Mancozeb at 40?mg?l^?1 inhibited fungal growth and provided lag phases >24 days at 10–20?mg?l^?1 and 15°C. OTA was observed only at 25°C and doses <10?mg?l^?1. At 15°C, copper oxychloride proved inhibitory at 800?mg?l^?1, while at 25°C growth was not delayed and only high doses decreased OTA levels. Sulfur was inhibitory or provided large lag phases at 5–8?g?l^?1 (at 15°C) while at 25°C growth took place even at 8?g?l^?1, although OTA levels were low or undetectable. The antifungal activity decreased in the order mancozeb?>?copper oxychloride?>?sulfur, and was lower at 25°C than at 15°C. OTA accumulation was affected by the type of fungicide, dose, temperature and time. The efficacy of these fungicides on the growth of A. carbonarius and A. ochraceus and OTA production in barley-based medium is assessed for the first time.     

Effect of gamma irradiation and sodium hydroxide treatment on the debittering of olive (Olea europaea) fruits

The effect of gamma irradiation and sodium hydroxide (NaOH) treatment on the debittering of olive (Olea europaea, var Surrany) fruits was investigated. Fruits were treated with 1, 2 or 3 kGy of gamma irradiation at a dose rate of 669 Gy h^?1. Irradiated and unirradiated fruits were processed with NaOH solution (11 g l^?1) for 3 or 6 h and washed once per day for 3 days. The fruits were then immersed in brine (56 g l^?1 sodium chloride) and stored for 12 months at room temperature. Dissolved organic and inorganic solids, Na⁺, K⁺ and Ca²⁺ contents, pH and electrical conductivity values were determined in the debittering solutions (lye, rinse and washing waters) and brines. Gamma irradiation significantly (p < 0.05) increased the dissolved organic and inorganic solids and the Na⁺ and K⁺ concentrations in the debittering solutions when the fruits were treated with NaOH for 3 h. On the other hand, gamma irradiation had no significant effect on these parameters, except for an increase in K⁺ concentration, when using NaOH solution for 6 h. Gamma irradiation with NaOH treatment for 3 h decreased the concentration of Ca²⁺ in the debittering solutions, whereas irradiation and treatment with NaOH solution for 6 h increased its concentration. © 2003 Society of Chemical Industry     

Rapid determination of nitrites in food using a diffuse UV-visible reflectance method

A simple, low-cost, sensitive and selective method for the determination of trace quantities of nitrite in foods such as cheese and cured meat using diffuse ultraviolet-visible reflectance was developed. It is based on the reaction of nitrite with sulphadiazine and α-naphthol, which produces a coloured product in basic medium. The reaction is carried out directly in the measuring cell. For cheese the limit of detection (LOD), expressed as NaNO₂, was estimated to be about 2.0?×?10^?2?mg?l^?1 (2.9?×?10^?7?mol?l^?1) in the final measuring solution and 0.17?mg?kg^?1 in cheese (2.5?×?10^?6?mol?kg^?1). The relative standard deviation (RSD) varied from 5% to 8% depending on the sample. For meat the LOD was estimated to be about 2.0?×?10^?2?mg?l^?1 (2.9?×?10^?7?mol?l^?1) in the final measuring solution and 0.13?mg?kg^?1 in meat (1.9?×?10^?6?mol?kg^?1). The RSD varied from 3% to 6% depending on the sample. The results of the proposed method were also compared with those obtained with the official method using the statistical Student's t-test and F-test procedures.     

Volatile flavour compounds in suspension culture of Agastache rugosa Kuntze (Korean mint)

For the production of volatile flavour compounds from Agastache rugosa Kuntze (Korean mint) suspension culture, callus was obtained from the leaves of A rugosa. Cell growth of A rugosa suspension culture was improved when cells were cultivated in Murashige and Skoog medium supplemented with 50 g l^?1 sucrose and 1 mg l^?1 2,4‐dichlorophenoxyacetic acid. Volatiles were isolated from a 15‐day‐old suspension culture by liquid–liquid continuous extraction and identified by gas chromatography/mass spectrometry. 3‐Hydroxy‐2‐butanone was the most abundant compound, followed by 2,4,5‐trimethyl‐3‐oxazoline, 1,2,4‐trimethylbenzene and 1,3‐butanediol. However, the volatile profile of the suspension culture was totally different from that of the intact plant. Fourteen aroma‐active compounds were detected by aroma extract dilution analysis. The most potent aroma‐active compounds representing characteristic aroma of A rugosa suspension culture were 2,3‐butanedione (buttery/cheese), (E,Z)‐2,6‐nonadienal (cucumber/melon) and (E,Z)‐2,6‐nonadien‐1‐ol (cucumber/sweet). Some alcohols and unknown compounds are thought to contribute to the wine‐like aroma characteristics of A rugosa suspension culture. Through a time course study, A rugosa suspension culture was revealed to have an inverse relationship between cell growth and flavour production. © 2001 Society of Chemical Industry     

In vitro antioxidant and antiproliferative activity of three rosemary (Rosmarinus officinalis L.) extract formulations

Antioxidant and antiproliferative activities of three rosemary extract formulations (VivOX 20, VivOX 40 and Inolens 50) with different contents of carnosic acid, carnosol and methylcarnosol were tested in vitro. Electron spin resonance measurements revealed that Inolens 50 extract that contained highest amount of carnosic acid was the most potent scavenger of hydroxyl (concentration of extract where 50% of its maximal scavenging activity is observed, that is, EC₅₀, 109.54 μg mL^?1), superoxide anion (EC₅₀ = 7.94 μg mL^?1) and 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) (EC₅₀ = 27.4 μg mL^?1)‐free radicals. Comparison of the radar charts of standard antioxidants and rosemary extracts showed similarity between antioxidant characteristics of Inolens 50 and chlorogenic and caffeic acids. Tested rosemary extracts exhibited significant (P ≤ 0.01) antiproliferative effect in cervix epitheloid carcinoma (HeLa), breast adenocarcinoma (MCF7) and colon adenocarcinoma (HT‐29) cell lines. In both MCF7 and HeLa cell lines, the extracts yielded very low IC₅₀ values (concentration of extract needed to inhibit cell growth by 50%), the most pronounced being for Inolens 50 in MCF7 (IC₅₀ = 9.95 μg mL^?1) and VivOX 20 in HeLa cell line (IC₅₀ = 10.02 μg mL^?1). The obtained results may provide support for the use of tested rosemary extracts as nutraceuticals and phytopharmaceuticals.     

The yeast flora of ensiled whole-crop maize

The yeast flora in samples of 13 different whole-crop maize silages was shown to be predominated by Candida krusei, C. lambica, Saccharomyces dairensis, S. exiguus, C. holmii or C. milleri. All these strains fermented glucose but, except for the latter three species, not sucrose, α-trehalose or raffinose. Under conditions resembling those in silage, i.e. at pH 4.0 in the presence of a complex nitrogen source, all strains assimilated lactic and acetic acids. This result suggests that the predominant yeasts in silage should not be distinguished into lactate utilisers and lactate non-utilisers. All strains, except those of Saccharomyces dairensis, tolerated acetic acid (5 g litre^?1) and grew at pH 4.0 in a mineral salts medium containing lactic acid (10 g litre^?1), acetic acid (5 g litre^?1) and yeast extract (1 g litre^?1). Growth in this medium was completely inhibited by the cationic detergent Arquad C33W (20 mg litre^?1), propionic acid (5 g litre^?1), benzoic acid (5 g litre^?1) or salicylic acid (10 g litre^?1).     

Mineral contents of some aromatic plants,their growth soils and infusions

BACKGROUND: In this study, 18 kinds of medicinal plants were collected together with their soils from different regions of Turkey and their macro‐ and micro‐element and heavy metal contents were determined by inductively coupled plasma atomic emission spectrometry (ICP‐AES). In soils, pH, electrical conductivity, carbonate (lime), organic matter, texture, P, K, Ca, Mg, Fe, Cu, Mn, Zn and B were analysed. In plants and extracts, P, K, Ca, Mg, Fe, Cu, Mn, Zn, B, Na, Al, Li, Pb, Ni, Cd, Co and Cr contents were determined. Also, correlations between soil and plant and between plant and extract were established. RESULTS: Element concentrations ranged between 0.11 and 5160 µg g^?1 in soil samples, between 0.14 and 54400 µg g^?1 in plant samples and between 0.039 and 22033 µg g^?1 in extract samples. While sage was rich in Fe (981.3 µg g^?1), basil was abundant in P (9.8 mg g^?1), K (54.4 mg g^?1), Ca (22.6 mg g^?1), Mg (3.1 mg g^?1) and Zn (46.05 µg g^?1) and mint was rich in Li (23.50 µg g^?1). Moreover, while high levels of P (4100.9 µg g^?1), K (22033 µg g^?1) and Mg (529.15 µg g^?1) were found in basil extract, Ca (5979.3 µg g^?1) was present at high concentration in marjoram leaf extract. Also, Fe (4.25 µg g^?1) and Zn (17.51 µg g^?1) were detected at high levels in lime flower and mint extracts respectively. CONCLUSION: It was concluded that aromatic plants are important sources of nutrients and essential elements. Copyright © 2007 Society of Chemical Industry     

A new strategy for improved glutathione production from Saccharomyces cerevisiae: use of cysteine‐ and glycine‐rich chicken feather protein hydrolysate as a new cheap substrate

BACKGROUND: Glutathione (GSH) is composed of the amino acids glutamic acid, cysteine and glycine. This study investigated the usability of chicken feather protein hydrolysate (chicken feather peptone, CFP) as a substrate for GSH production from Saccharomyces cerevisiae. RESULTS: CFP was found to be rich in ash (36.7 g per 100 g), protein (61.1 g per 100 g) and minerals (S, P, K, Ca, Fe, Na and Mg). It also had high contents of cysteine and glycine. CFP augmented biomass and GSH production by 53 and 115% respectively compared with the control medium. The highest biomass (17.4 g l^?1) and GSH (271 mg L^?1) concentrations were attained in CFP medium. The second highest biomass (16.8 g l^?1) and GSH (255 mg L^?1) concentrations were obtained in fish peptone medium. It was assumed that the high mineral, cysteine and glycine contents of CFP were related to cell growth and GSH synthesis in S. cerevisiae. CONCLUSION: This is the first report on the effect of cysteine‐ and glycine‐rich protein hydrolysates on GSH production from S. cerevisiae. In this regard, CFP was tested for the first time as a GSH production substrate. As an additional contribution, a new hydrolysis process was developed for the preparation of protein hydrolysates. © 2012 Society of Chemical Industry     

Inhibition of Listeria monocytogenes by Nisin Combined with Grape Seed Extract or Green Tea Extract in Soy Protein Film Coated on Turkey Frankfurters

The objective of this study was to evaluate the inhibitory effect of grape seed extract (GSE), green tea extract (GTE), nisin and their combinations (nisin with either GSE or GTE) against Listeria monocytogenes. The inhibitory effect of these natural compounds was evaluated in phosphate buffer solution (PBS) medium containing approximately 10⁹ colony‐forming units (CFU/mL) of L. monocytogenes. The effectiveness of these compounds in a meat model system was evaluated by surface inoculation (approximately 10⁶ CFU/g) of L. monocytogenes onto turkey frankfurters. The inoculated frankfurters were dipped into soy protein film‐forming solutions with and without the addition of antimicrobial agents (GSE 1% or GTE 1% or nisin 10000 IU or combinations). Samples were stored at either 4 °C or 10 °C. The inhibitory effects of edible coatings were evaluated on a weekly basis for 28 d. The greatest inhibitory effect was observed in the PBS medium containing GSE (1%) and nisin (10000 IU/mL), which caused a 9‐log cycle reduction of L. monocytogenes population after 3 h incubation at 37 °C. In the meat system, the L. monocytogenes population (7.1 CFU/g) was decreased by more than 2 log cycle after 28 d at 4 °C and 10 °C, in the samples containing nisin (10000 IU) combined with either GSE (1%) or GTE (1%). This research has demonstrated that the use of an edible film coating containing both nisin and natural extracts is a promising means of controlling the growth and recontamination of L. monocytogenes on ready‐to‐eat meat products.     

Effect of residual fertility and direct fertilisation on kernel,protein and oil yield of peanut (Arachis hypogaea L) grown in rice fallows

Kernel (2814–3467 kg ha^?1), protein (555–759 kg ha^?1) and oil (124–1556 kg ha^?1) yields of peanut (Arachis hypogaea L) varied significantly due to the residual effect of organic manures and inorganic fertilisers together. It was also observed that direct application of recommended fertilisers (25 N, 72 P₂O₅ and 37-5 K₂O kg ha^?1) gave the highest kernel (3669 kg ha^?1), protein (786 kg ha^?1) and oil (1606 kg ha^?1) yields. The reduction in kernel, protein and oil yield from the recommended level of fertilisers to half the recommended level of fertilisers was about 16, 15 and 12% while it was about 25, 33 and 27% with no fertiliser. Thus, the results revealed that the nutrients applied partly through organic manures and inorganic fertilisers to Kharif rice exhibits significant residual effects on the succeeding upland crop and hence the fertilisation must be considered not only for individual crops but also for the cropping system as a whole.     

Protection of Fibre Flax Crop Against Flea Beetles and Seedling Blight Using Compound Seed-Dressers

Abstract

The trial was carried out at Upyte Research Station of the Lithuanian Institute of Agriculture during the period 1999–2001, where flax (Linum usitatissimum L.) cv. ‘Baltuciai’ had been grown. The effect of compound seed-dressers RAPCOL FDL 323 CS (active ingredients: insecticide phurathiocarb 300 g l^?1 + fungicide metalaxil 20 g l^?1 + fungicide fludioxonil 3 g l^?1) (3000 ml 100 kg flaxseed^?1) and CRUISER OSR 321.3 FS (active ingredients: insecticide tiametoxam 280 g l^?1 + fungicide metalaxil-M 33.3 g l^?1 + fungicide fludioxonil 8 g l^?1) (dose rates 100, 250, 500, 750 and 1000 ml 100 kg flaxseed^?1) on the occurrence of flea beetles and seedling blight in flax crop when compared to the effect of seed-dresser Vitavax FF 200 (active ingredients: carboxine 200 g l^?1 + thiram 200 g l^?1) and insecticide Fastac 10 EC (active ingredient: alphacypermethrin 100 g l^?1) has been investigated.

The experimental findings suggest that 49.0 to 90.5% of flax plants were affected by flea beetles (Aphthona euphorbiaeSchr., Longitarsus parvulusPayk.) annually in the plots sown with untreated seed. Significantly fewer affected plants were identified in the plots sown with the seed treated with phurathiocarb 900 g + metalaxil 60 g + fludioxonil 6 g 100 kg^?1 seed (Rapcol, 3 l100 kg flaxseed^?1) and tiametoxam 28 g + metalaxil-M 3.33 g + fludioxonil 0.8 g 100 kg^?1 seed or tiametoxam 70 g + metalaxil-M 8.325 g + fludioxonil 2 g 100 kg^?1 seed (Cruiser,100 ml or 250 ml 100 kg^?1). Tiametoxam + metalaxil-M + fludioxonil, applied at higher dose rates (Cruiser, 500–1000 ml 100 kg^?1) gave a higher efficacy. The incidence of seedling blight (Colletotrichum lini (Westerdijk) Tochinai) was lower in the plots sown with the seed treated with compound seed-dressers. The impact of compound seed-dressers was noticed even at the flax 4–6 pairs of leaves stage.     

Comparison of the performances of different fermentation strategies on cell growth and bacteriocin production by Lactobacillus curvatus CWBI‐B28

The dynamics of cell growth and bacteriocin production by Lactobacillus curvatus CWBI‐B28 in modified De Man/Rogosa/Sharp (mMRS) broth with various concentrations of glucose and complex nitrogen source (CNS; peptone, yeast extract and meat extract) was investigated in flask fermentations and in a laboratory fermentor using batch and fed‐batch cultivations. In fed‐batch fermentation the rate of feeding of the reactor with the substrates was either maintained constant (0.12 L h^?1) or varied exponentially as a function of time. The results showed that both cell growth and bacteriocin activity were influenced by changes in the concentrations of glucose and CNS. Optimal growth and bacteriocin activity were obtained in mMRS broth containing 40 g L^?1 glucose and 40 g L^?1 CNS (mMRS_40/40). A bacteriocin titre of 4266 AU mL^?1 and a cell count of 8.7 log colony‐forming units (cfu) mL^?1 were recorded when this medium was used for cultivation. In batch fermentation using the same medium, a higher cell count (9.5 log cfu mL^?1) and twice as much bacteriocin as in flask fermentation were produced. The highest bacteriocin titre (8533 AU mL^?1) was obtained with fed‐batch fermentation at an exponentially varying rate of feeding. Bacteriocin activity and cell dry mass did not always correlate. Copyright © 2007 Society of Chemical Industry     

The effects of heating and chemical treatment on the haem and non-haem iron content of heat-induced porcine blood curd

The effect of heating temperature (40–80°C), time (0–50 min), additions of ascorbic acid (0–5 g litre^?1) and sodium nitrite (0–200 mg litre^?1) on total, non-haem and haem iron of heat-induced porcine blood curd (a famous edible blood food in Taiwan) was investigated. The results show that non-haem iron content increased significantly (P < 0.05) when heated at above 55°C and was enhanced linearly (r = 0.96) with heating time at 80°C, while haem iron decreased relatively. In addition, a non-haem iron increase was observed in ascorbic acid, the maximum found with treatment at 4 g litre^?1. On the contrary, haem iron content increased with the presence of sodium nitrite and there was a significant change with addition above 50 mg litre^?1.     

Antifungal activity of plant extracts against Colletotrichum lagenarium, the causal agent of anthracnose in cucumber

BACKGROUND: Colletotrichum lagenarium is an important plant‐pathogenic fungus that causes anthracnose of cucumber, a disease that is widespread under both greenhouse and field cultivation. To find a promising method for the control of this disease, extracts of eight plants from China were screened in the study presented here. RESULTS: The results showed that the extract of Cinnamomum camphora (L.) Presl had significantly greater inhibitory activity against C. lagenarium than the other seven plant extracts tested in vitro. At 5 days after inoculation in a potted seedling experiment, C. camphora extract demonstrated 95% control of C. lagenarium at a concentration of 16 mg mL^?1, and the MIC₅₀ was 2.596 mg mL^?1. Microscopic observation showed that this extract had a significant impact on the morphology of the fungus, leading to shorter hyphae that were more branched; this observation was associated with the inhibition of mycelial growth. Stability assays revealed that the extract was relatively stable at 80 °C, under acidic conditions and when exposed to light and short periods of UV radiation. CONCLUSION: These results demonstrated that the extract from C. camphora could be used as a potent phytochemical fungicide. Copyright © 2012 Society of Chemical Industry     

Bioactivities of essential oil and extract of Thymus argaeus,Turkish endemic wild thyme

BACKGROUND: Thymus argaeus Boiss. & Bal. (Lamiaceae), an endemic plant species of Turkey known as wild thyme, is traditionally used as a spice and a wild tea in the Inner Anatolia region of Turkey. In this study the composition of the essential oil and the antimicrobial and antioxidant effects of the methanolic extract and essential oil of T. argaeus were determined. RESULTS: The main components of the essential oil were linalool (499 g kg^?1), α‐terpineol (150 g kg^?1), linalyl acetate (97 g kg^?1) and thymol (94 g kg^?1). The total phenolic, flavanol and flavonol contents of the extract were 83.31 ± 0.59 mg gallic acid equivalent g^?1, 6.26 ± 0.00 mg catechin equivalent g^?1 and 28.81 ± 0.21 mg rutin equivalent g^?1 respectively. The antioxidant activities of the extract and essential oil determined by the 2,2‐diphenyl‐1‐picrylhydrazyl radical‐scavenging method were 830.18 ± 0.42 and 20.47 ± 2.3 mg g^?1 respectively. The antimicrobial activities of the extract and essential oil against 13 bacteria and two yeasts were studied by the agar diffusion method. The micro‐organisms most sensitive to the essential oil were Aeromonas hydrophila and Pseudomonas aeruginosa, while the micro‐organism most sensitive to the extract was P. aeruginosa. CONCLUSION: Only the extract of T. argaeus could be used as a natural antioxidant, while both the extract and the essential oil could be useful as natural antimicrobial agents in food preservation. Copyright © 2009 Society of Chemical Industry     

A simple gold plate electrode modified with Gd-doped TiO2 nanoparticles used for determination of trace nitrite in cured food

A simple gold plate electrode (GPE) based on a gadolinium-doped titanium dioxide (Gd/TiO₂) ultrathin film was successfully constructed by using a surface sol-gel technique, and used for the detection of trace amounts of nitrite in cured foods. The Gd/TiO₂ nanoparticles were synthesised and characterised via scanning electron microscopy (SEM) and X-ray diffraction (XRD), indicating that the Gd-doped TiO₂ formed an anatase phase through roasting at 450°C, generating actively interstitial oxygen at the interface of the surface of TiO₂ lattice surrounded by Gd³⁺. The electro-catalytic effect for oxidation of nitrite on the modified electrode was investigated by cyclic voltammetry in 0.10?mol?l^?1 sulfuric acid media solution, showing that the modified electrode exhibited excellent response performance to nitrite with good reproducibility, selectivity and stability. The catalytic peak current was found to be linear with nitrite concentrations in the range of 8.0?×?10^?7 to 4.0?×?10^?4??mol?l^?1, with a detection limit of 5.0?×?10^?7?mol?l^?1 (S/N?=?3). The modified electrode could be used for the determination of nitrite in the cured sausage samples with a satisfactory recovery in the range of 95.5–104%, showing its promising application for food safety monitoring.     

The potential of sunflower as a crop for ensilage

The chemical composition and nutritive value of sunflower, cv. Armavirec, was examined at 12 stages of growth. Maximum yield of dry matter (18.2 t ha^?1) occurred at the dough seed stage. Ether extract showed a five-fold increase with the development of the seed. This increase was reflected in the gross energy value which was maximal at 19.1 MJ kg^?1 dry matter at the dough seed stage. In-vitro organic matter digestibility was highest at the onset of flowering when the estimated metabolisable energy value was 10.5 MJ kg^?1 dry matter. Throughout the sampling period the calcium to phosphorus ratios varied from 3.9-5.9:1, an imbalance which would have to be redressed on diets based largely on sunflowers. Fresh and wilted sunflowers were successfully ensiled at the flowering stage, without the use of additives. pH values of the resulting silages were 3.86 and 4.01. The silages were each fed to six cross-bred wethers and voluntary dry matter intakes were 23.9 and 26.5 g kgW^?1 for the fresh and wilted silages respectively. For the fresh silage, intakes of digestible organic matter and digestible nitrogen were 612 and 13.6 g day^?1 compared with 684 and 16.7 g day^?1 for the wilted silage. Nitrogen retention increased with increase in silage dry matter. The optimum time of cutting for yield of nutrients is at the milky ripe stage. The composition of the crop at this stage should facilitate a satisfactory preservation by ensiling. The crop provides a high yield of dry matter over about 10 weeks in late summer and could provide a valuable standby forage crop for grass in dry areas.     

Evaluation of the conditions of carotenoids production in a synthetic medium by Sporidiobolus salmonicolor (CBS 2636) in a bioreactor

This work studied the cultivation conditions for the production of carotenoids by Sporidiobolus salmonicolor (CBS 2636) in a bioreactor. A Plackett–Burman design was used for the screening of the most important factors, followed by a complete second order design, to maximise the concentration of total carotenoids. The maximum concentration of 3425.9 μg L^?1 of total carotenoids was obtained in a medium containing 80 g L^?1 glucose, 15 g L^?1 peptone and 5 g L^?1 malt extract, with an aeration rate 1.5 vvm, 180 r.p.m., 25 °C and an initial pH of 4.0. Fermentation kinetics showed that the maximum concentration of total carotenoids was reached after 90 h of fermentation. Carotenoid bio‐production was partially associated with cell growth. The specific carotenoid production (Y_P/X) was 238 μg carotenoids/g cells, whereas Y_P/S (substrate to product yield) was 41.3 μg g^?1. The specific growth rate (μ_x) was 0.045 h^?1. The highest cell and total carotenoid productivity were 0.19 g L^?1 h^?1 and 56.9 μg L^?1 h^?1, respectively.     

天麻提取物及其3 种主要成分对灰树花产胞外漆酶和菌丝体的影响

以天麻提取物为外源添加物,加至灰树花液体深层发酵体系中,通过外源诱导实验,考察天麻提取物对灰树花液体发酵产菌丝体及胞外漆酶的影响,并进一步重点研究起显著影响作用的关键成分。研究表明,天麻提取物及单一成分天麻素（gastrodin,GA）、对羟基苯甲醛（p-hydroxylbenzaldehyde,HBA）、对羟基苯甲醇（p-hydroxybenzyl alcohol,HA）均对灰树花菌丝体和胞外漆酶活力有显著的促进作用。结果显示,当添加3?g/L的天麻醇提物时,对灰树花菌丝体生物量和胞外漆酶活力有最大的促进作用,与对照组相比,分别提高了1.62?倍和7.41?倍（P＜0.05）。同时,利用高效液相色谱对3?g/L天麻醇提物中的GA、HBA、HA含量进行分析,以相应量添加到灰树花发酵体系中。结果表明,HA和HBA均能显著提高灰树花漆酶活力和菌丝体生物量,与添加3?g/L天麻醇提物实验组相比,添加HA使酶活力提高10.25%,生物量增加9.17%。本研究可为中药提取物及成分促进真菌生长和产漆酶提供理论依据。     

Inhibitory effect of mineral ion accumulation on high density growth of the hyperthermophilic archaeon Sulfolobus solfataricus

A fed-batch operation for high density cultivation of Sulfolobus solfataricus (DSM 1617) in a bench-top fermentor using a feed medium composed of glucose and yeast extract was investigated. The highest maximal cell density obtained in controlled fed-batch cultures was 21.7 g/l. Although higher yeast extract concentrations in the medium favored greater cell biomass yield, cell growth ceased with low cell densities. It was observed that large amounts of inorganic ions, such as sulfate, ammonium, potassium and phosphate ions, were accumulated in the culture broth at higher yeast extract concentrations. This was due to either the addition of the titrant or feeding of yeast extract during cultivation. Fed-batch cultures with additional mineral salts in the feed medium showed much lower cell biomass, indicating that accumulation of inorganic ions has a significant inhibitory effect on the growth of S. solfataricus. Inhibition of cell growth by the presence of mineral ions was further confirmed by the batch culture experiments. Some plausible mechanisms which can account for the growth inhibition at higher mineral ion concentrations have been suggested.