Hydrocarbon fermentations: Oxidation mechanism and nonionic-surfactant effects in a culture of Candida lipolytica

Oxidation rates of several alkane substrates by C. lipolytica ATCC 8661 grown on n-dodecane were determined using a Warburg Respirometer. Substrates were emulsified using Span 20, Span 80, Tween 20, Tween 80, and Triton X-100 surfactants and the effects of these surfactants on oxidation and growth were determined. The oxidation rates of a number of intermediates, including lauric acid and lauryl alcohol, were also assessed. Responses of dodecane-grown C. lipolytica to select substrates were compared to the corresponding behavior with glucose-grown yeast and with baker's yeast. The role of surfactants in hydrocarbon fermentations is discussed in the light of the present and previously published data.     

Factors influencing β-glucosidase production, activity and stability inNectria catalinensis

The influence of different cultivation conditions on β-glucosidase production and of some parameters on the activity and stability of this enzyme were studied inNectria catalinensis. Maximal β-glucosidase production was achieved with ammonium nitrate (0.5 g N/L) as nitrogen source. Tween 80, Tween 20 and Triton X-100 increased β-glucosidase yields, Tween 80 was the most effective for enzyme release and growth at a concentration of 3.4 mmol/L. On the other hand, Tween 20 and Triton X-100 had an inhibitory effect onN. catalinensis growth. A temperature of 23°C and an initial pH of cultures of 6.5 were optimal for biomass and β-glucosidase production. Under optimal cultural conditions (ammonium nitrate, 0.5 g N/L; Tween 80, 3.4 mmol/L; 23°C; initial pH 6.5) the β-glucosidase yield was increased more than five fold respect to the initial state. Optimal temperature for β-glucosidase activity was 45°C, the initial activity dropped 60 % after 6 h of incubation at this temperature. Optimal pH for enzyme activity was 5.3. At this pH the β-glucosidase was completely stable after 3 d of incubation. TheV andK _m values calculated from Lineweaver-Burk and Eadie-Hofstee plots were 0.23 μmol 4-nitrophenol per min per mg of protein and 0.25 mmol 4-nitrophenol β-d-glucopyranoside per L, respectively. The activation energy according to Arrhenius plot was 49.6 KJ/mol.     

Effect of surfactants and identification of metabolites on the biodegradation of fluoranthene by basidiomycetes fungal isolate Armillaria sp. F022

The effects of structure and concentration of surfactants on the biodegradation of fluoranthene, a three rings polycyclic aromatic hydrocarbon in the aqueous phase, as well as their effects on the biodegradation and enzyme activity were investigated. The toxicity ranking of studied surfactants is: non-ionic Tween 80 <anionic sodium dodecyl sulfate <cationic Tetradecyltrimethylammonium bromide. The maximum growth of Armillaria sp. F022 (>4,500 mg/L) was showed by Tween 80 (10 mg/L) culture, manifesting that the non-ionic surfactant present in the culture were beneficial to the fungal growth. Laccase showed the highest enzymes activity in all surfactants culture. Non-ionic Tween 80 showed a significant result for laccase activity (1,902 U/L) in the Armillaria sp. F022 culture. The increased enzymes cumulative activity may stem directly from the rising fluoranthene biodegradability as addition of appropriate surfactants. The biotransformation of fluoranthene was greatly improved by Tween 80, and totally fluoranthene degradation was obtained as Tween 80 was 10 mg/L. Two fluoranthene metabolites were isolated from the culture medium and analyzed by a thin layer chromatography, UV visible spectrometer and gas chromatography–mass spectrometry (GC–MS). The oxidation of fluoranthene is initiated by oxygenation at the C-2,3 positions resulting 9-fluorenone. At the end of experiment, one metabolite was detected in the culture extract and identified as phthalic acid. Evidently, Armillaria sp. F022 seems efficient, high effective and deserves further application on the enhanced bioremediation technologies for the treatment of fluoranthene-contaminated soil.     

Characteristics and Effects of Temperature and Surfactants on Bacteriocin-Like Inhibitory Substance Production of Soil-Isolated Lactobacillus animalis C060203

A soil isolate of Lactobacillus animalis was found to produce a bacteriocin-like inhibitory substance (BLIS) with a wide inhibitory spectrum against Gram-positive bacteria. The isolate exhibited high BLIS production in broth containing surfactants, such as Tween 20 and 80, but low BLIS production in the absence of surfactants. Culture temperature also had an effect on BLIS production. This is the first report to study the production and characteristics of L. animalis BLIS.     

Determination of ligninase activity in P. chrysosporium pellets with diffuse reflectance spectrophotometry

Diffuse reflectance spectrophotometry was applied for measuring ligninase activity in pellets of Phanerochaete chrysosporium. Enhanced ligninase activity in pellets and in growth medium were detected in cultures supplemented with oleic acid emulsified with Tween 80, Tween 80, hydrophilic (alcoholic) residue of Tween 80 hydrolysate, Tween 20, and (15OE)C_18:1. In cultures with low extracellular ligninase activity, low activity in pellets was also observed. Our results indicate that the stimulatory effect of the tested surfactants cannot be contributed solely to promotion of ligninases through the cell membrane. Correspondence to: D. Letan     

Callus induction and maintenance of Zea mays kernels

Summary Totipotent tissue cultures of maize (Zea mays L.) have previously been initiated from various explant tissues. In this paper, we present an alternative source of callus induction.A callus of maize (G 204 hybrid) was obtained from intact kernels grown on Linsmair and Skoog RM medium supplemented with 20 mg 2,4-dichlorphenoxyacetic acid (2,4-D) per litre. The callus growth was greatest from the first node of the seedling shoot. Occasionally, callus growth was observed from the radicle and coleopticle regions. The callus was easily transferred and maintained on a medium with 2 mg/L 2,4-D. This callus formed numerous roots and leaf-like structures when grown on a medium containing 800 mg/L yeast extract, 30 g/L sucrose and 10 g/L agar.     

表面活性剂对分枝杆菌KR2菌株降解菲的影响

采用同位素示踪方法,从表面活性剂的浓度、离子类型和直链长度三方面研究了表面活性剂对分枝杆菌KR2菌株降解菲的影响。结果表明,表面活性剂的存在不能促进KR2菌对菲的降解;高浓度表面活性剂(≥20mg·L^-1)的存在,使菲的降解出现延迟期,非离子表面活性剂Tween80在低浓度时(≤10mg·L^-1)可以优先作为营养基质被分枝杆菌KR2菌株利用,表面活性剂的离子类型对菲降解的抑制作用的顺序为阳离子表面活性剂TDTMA>阴离子表面活性剂LAS>非离子表面活性剂Tween80,表面活性剂的直链长度对菲降解的影响为直链越短,对微生物的毒性越大,菲降解得越不完全。     

Influence of nonionic surfactants and hydroxypropyl-β-cyclodextrin on the biodegradation of nitrobenzene

This paper investigates the effect of two nonionic surfactants (Tween 80 and Triton X-100) and hydroxypropyl--cyclodextrin (HP--CD) on the biodegradation of nitrobenzene (NB) by Acinetobacter sp. in liquid cultures at different dosages as well as the fate of both surfactants. When the initial concentration of NB was about 400 mg/l, neither Tween 80 nor HP--CD had any effect on the degradation of NB. However, Triton X-100 retarded the full removal of NB and the bacterial growth entering the stationary phase. While the initial concentration of NB was increased to about 850 mg/l, they all significantly enhanced the extent and rate of biodegradation if they were added at concentrations above 2000 mg/l. HP--CD could not be utilized by Acinetobacter sp. as the sole carbon source whereas both surfactants could, but no surfactant depletion was observed during the biodegradation of NB. So the rapid bacterial growth observed in the presence of each additive should be attributed to the rapid metabolism of NB. Both surfactants would promote the degradation of NB more than HP--CD would do if their dosages were increased properly.     

Studies of soil moisture stress in barley (Hordeum vulgare L.)

Summary The objective was to find the optimum range of water contents for inducing better growth, physiological efficiency and yield potential of barley plants (Hordeum vulgare L. var. K18). A pot culture experiment was conducted in the Division of Crop Physiology and Biochemistry Kanpur-2. The plants were subjected to various soil moisture stresses,i.e., 0.15, 0.30, 0.45, 0.60 and 0.75 atm tension throughout the crop growth period measured by irrometers.Plants maintained at 0.45 soil moisture tension required 19.07 litre of water and had the best water use efficiency (1765 mg dm/litre of water) which favourably influenced the leaf water balance (85.9%), plant growth as measured by plant height (85.4 cm) and tiller production (35.6) per hill, photosynthetic efficiency (2.185 mg CO₂/g dm/h), grain number (722) and grain yield (33.7 g) per hill while plants irrigated at a tension greater than 0.45 SMT did not develop as well. However, protein and gluten percentage increased gradually with the subsequent increase in soil moisture tension. On the other hand respiration rate (2.090 mg CO₂/g dm/hr) and leaf area (4375 cm²) were recorded to be the highest at 0.60 and 0.30 atm SMT respectively.Thus it is suggested that for reaping high harvest of barley crop, the physiological need of water (19.07 litre) in total of plant life should be made available through scheduled irrigation based on maintenance of plant at 0.45 SMT from seeding to maturity.     

Effects of stocking density and food density on survival,growth and yield of laboratory-reared larvae of sea bream Archosargus rhomboidalis (L.) (Sparidae)*

Growth and survival of sea bream, Archosargus rhomboidalis (L.) larvae were affected by both abundance of eggs that were initially stocked in 75 1 rearing systems and by the concentration of copepod nauplii and copepodites that were fed to larvae. Stocking levels were 2, 4, 8,16 or 32 per litre while food abundance was maintained at approximately 100, 500, 1500 or 3000 per litre. Experiments were of 16 days duration at 26° C. Survival was best, often exceeding 60%, when food levels were 1500 or 3000 per litre and when stocking density did not exceed 8 eggs per litre. Growth was best at the lowest stocking densities and highest food levels. The highest total yields in wet weight occurred at 8 per litre stock density and 3000 per litre food level. Mean wet weight per survivor and yield per stocked egg were greatest at the lowest stocking densities and highest food levels. A 500 per litre food level was marginal for growth and survival, and 100 per litre produced significant survival only at the 2 per litre stocking density. Two experiments at 6000 and 10 000 per litre food levels at 4 per litre stock density gave the best observed growth, and survival as good as in any other experiments. Possible relations between sea bream larvae and their food supply in the natural environment are discussed. Results also are discussed in terms of their possible contribution to aquaculture efforts.     

Adsorption of surfactants on a <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> strain and the effect on cell surface lypohydrophilic property

The adsorption behavior of five surfactants, cetyltrimethylammonium bromide (CTAB), Triton X-100, Tween 80, sodium dodecyl sulfate (SDS), and rhamnolipid, on a Pseudomonas aeruginosa strain and the effect of temperature and ionic strength (IS) on the adsorption were studied. The change of cell surface lypohydrophilic property caused by surfactant adsorption was also investigated. The results showed that the adsorption kinetics of the surfactants on the cell followed the second-order law. CTAB adsorption was the fastest one under the experimental conditions, and it took longest for SDS adsorption to equilibrate because of electric repulsion. The adsorption of Triton X-100 and Tween 80 was characterized by short equilibration time, and rhamnolipid adsorption reached equilibrium in about 90 min. The adsorption isotherms of all the surfactants on the bacterium fitted Freundlich equation well, but the adsorption capacity and mode were variations for the surfactants as indicated by k and n parameters in the equations. The adsorption mode for all the surfactants except SDS is probably hydrophilic interaction because the adsorption totally turned the cell surface to be more hydrophobic. Neither the temperature nor the IS had significant effect on CTAB adsorption, but higher IS significantly enhanced SDS adsorption and modestly strengthened adsorption of Triton X-100, Tween 80, and rhamnolipid. Higher temperature strengthened adsorption of SDS but weakened the adsorption of Triton X-100, Tween 80, and rhamnolipid.     

Degradation of fluoranthene by a newly isolated strain of <Emphasis Type="Italic">Herbaspirillum chlorophenolicum</Emphasis> from activated sludge

A fluoranthene-degrading bacterial strain FA1 was isolated from activated sludge and identified as Herbaspirillum chlorophenolicum, a newfound bacterial species that can grow well on fluoranthene as sole carbon and energy source. The kinetic characteristic of strain FA1 was tested in the aqueous model system (AMS) and the effects of nonionic surfactants on fluoranthene biodegradation in the AMS were then investigated. Tween 80 exhibited the best solubilization capacity for fluoranthene among three surfactants and its bioavailability decreased with an increase in its concentration and its degradation kinetics fit well with the first-order of power index model. The biotransformation of fluoranthene was greatly improved by Tween 80, and 58.5% fluoranthene degradation was obtained as Tween 80 was 100 mg/l. However, the bioavailability of fluoranthene decreased gradually with the increase of Tween 80 concentration. Bioremediation tests for fluoranthene in soil–water system were designed further to examine the degrading ability of strain FA1 with the presence of indigenous flora or not. The measurements showed that in the presence of indigenous flora, the optimum 30-day fluoranthene degradation in soil–water system reached 77.4%. Evidently, strain FA1 seems both efficient and high-effective and deserves further exploration on the enhanced bioremediation technologies for the treatment of fluoranthene-polluted soil.     

Chemical suppression of the sexual stage of Leptosphaeria maculans on oil-seed rape and turnip seed crop straw

A selection of fungicides, herbicides and surfactants and urea were tested for their effect on the production of pseudothecia and ascospore release of Leptosphaeria maculans present on oil-seed rape straw and turnip seed crop straw. The fungicides ethyl mercury phosphate, triarimol, fenarimol, carbendazim, tridemorph and benomyl, each at 1 g/litre, the herbicides dinoseb and diquat, each at 10 g/litre the surfactants Bradasol, Cetrimide, Deciquam 222, Hyamine 1622 and Maxonol N, each at 50 g product/litre, and urea at 150 g/litre, applied to straw before pseudothecia had formed were more than 90% effective in preventing further development. These chemicals were also effective in preventing further ascospore production when applied to straw bearing mature pseudothecia but only dinoseb and urea prevented the release of mature ascospores. The results suggest that it may be possible to break the life cycle of L. maculans by chemical treatment and thereby obviate the need for subsequent control measures.     

Effects of monorhamnolipid and Tween 80 on the degradation of phenol by Candida tropicalis

The effects of the biosurfactant monorhamnolipid (monoRL) and the chemical surfactant Tween 80 on the degradation of phenol by Candida tropicalis CICC 1463 were studied. Both surfactants impeded the decay in cell concentrations at the beginning of the fermentation and enhanced the cell growth thereafter. They also increased the degradation efficiencies of 500 mg/L phenol from 86.9% in control to above 99.0% for all test concentrations within 30 h. The monoRL could also be degraded by the C. tropicalis. These results indicate that the surfactants could diminish the toxicity of phenol to the yeast, increase cell growth and improve phenol removal. The monoRL is better than Tween 80 because of biodegradability.     

Growth-substrate dependent dechlorination of 1,2-dichloroethane by a homoacetogenic bacterium

A rod shaped, gram positive, non sporulating Acetobacterium strain was isolated that dechlorinated 1,2-dichloroethane (1,2-DCA) to ethene at a dechlorination rate of up to 2 nmol Cl^- min^-1 mg^-1 of protein in the exponential growth phase with formate (40 mM) as the substrate. Although with other growth substrates such as pyruvate, lactate, H₂/CO₂, and ethanol higher biomass productions were obtained,the dechlorination rate with these substrates was more than 10-fold lower compared with formate growing cells. Neither cell extracts nor autoclaved cells of the isolatedAcetobacterium strain mediated the dechlorination of 1,2-DCA at significant rates. The addition of 1,2-DCA to the media did not result in increased cell production. No significant differences in corrinoid concentrations could be measured in cells growing on several growth-substrates. However, these measurements indicated that differences in corrinoid structure might cause the different dechlorination activity. The Acetobacterium sp. strain gradually lost its dechlorination ability during about 10 transfers in pure culture, probably due to undefined nutritional requirements. 16S rDNA analysis of the isolate revealed a 99.7% similarity with Acetobacterium wieringae. However, the type strains of A. wieringae and A. woodii did not dechlorinate 1,2-DCA.     

Production of chitinase and its optimization from a novel isolate Alcaligenes xylosoxydans: potential in antifungal biocontrol

A novel, highly chitinolytic strain of Alcaligenes xylosoxydans was isolated which showed potential for use as an antifungal biocontrol agent for the control of two fungal plant pathogens. It could degrade and utilize dead mycelia of Rhizoctonia bataticola and Fusarium sp. (fungal plant pathogens of Cajanus cajan). In vitro it could inhibit the growth of Fusarium sp. and R. bataticola. Chitin at 10–15 g/l was found to be good carbon and nitrogen source. Alcaligenes xylosoxydans showed optimum chitinase production at 72 h, pH optima at 8 and growth peak at 120 h. Yeast extract, arabinose, Tween 20 and several other surfactants enhanced chitinase production.     

Changes in the content of glycogen and its metabolites during acute exposure ofAnabas testudineus (Bloch) to furadan

Significant differences were observed in glycogen metabolism ofAnabas testudineus exposed to an acute lethal (1.56 mg/litre) and a sublethal (0.56 mg/litre) concentration of furadan. At sublethal concentration, the muscle glycogen which was utilized during the early periods of exposure, was replenished in the later period of exposure and at 120 h, the muscle glycogen levels were higher than the control. At higher concentration, the liver glycogen levels showed an increase presumably at the expense of fuel reserves of the muscle.     

A rationale for the appropriate amount of inoculum in ready biodegradability tests

Several screening methods at the so-called ready biodegradability level are suitable to test poorly soluble substances. Typical for these tests is that mineralization is evaluated from monitoring oxygen uptake or carbon dioxide production. Unfortunately, they suffer from a rather low precision in the calculated percentage of mineralization caused by subtracting a too high inoculum control measurement from the response in the test system. Criteria for blank oxygen consumption, due to the metabolic activity of the inoculum, are proposed from which maximum amounts of activated sludge or secondary effluent per litre test medium can be derived to be used as an appropriate inoculum. Both for current and future standardized tests the precision of the method can be kept within acceptable margins. Inoculum material was sampled from 40 communal biological waste water treatment plants. From endogenous respiration rates it was derived that the concentration of secondary effluent in the Closed Bottle Test can be increased up to 50 mL/L but that in respirometry tests inoculated with activated sludge the appropriate concentration is 10 mg/L dry matter or below, depending of the design of the test system.List of abbreviations BOD biological oxygen demand - CBT Closed Bottle Test - C _as inoculum concentration in mg dry solids of activated sludge per litre test medium - C _ef inoculum concentration in ml secondary effluent per litre test medium - C _ss dry weight content of activated sludge (g/L) - CFU colony forming units - DO_7d dissolved oxygen concentration (mg/L) after 7 days - ISO International Organization for Standardization - NEN Dutch Organization for Standardization - O _c oxygen capacity in mg oxygen per litre vessel volume - OECD Organisation for Economic Co-operation and Development - Ox _as oxygen consumption after one week in mg oxygen per mg dry weight activated sludge - Ox _ef oxygen consumption after one week in mg oxygen per mL secondary effluent - Ox _ef [n] oxygen consumption after one week in mg oxygen per n mL secondary effluent - Ox _flask oxygen uptake in mg per litre flask volume - RBT Ready Biodegradability Test - SLR sludge loading rate in kg O₂/kg dry weight·d - ThOD theoretical oxygen demand - TPCBT Two Phase Closed Bottle Test - V _a volumes of air and water per litre vessel - V _w volume, respectively - _a concentration of oxygen in air at 20° C and 101.5 kPa - _s saturation oxygen concentration in te aqueous phase     

Effect of Tween 80 on the growth of Mycobacterium avium complex

The effect of Tween 80 on the growth of Mycobacterium avium complex (MAC) in liquid culture condition was investigated. Observation of the colony-forming units (CFU) and the morphology of MAC with transmission and scanning electron microscopy showed that Tween 80 at 0.05% in the medium (ca. 0.5 mg/ml) had bacteriostatic action and caused cell elongation. Tween 80 at 0.5% or more in the medium (ca. 5 mg/ml) reduced the quantity of MAC glycolipids and also led to false positive or positive results in biochemical tests for mycobacterial identification using nitrate reductase, urease, or arylsulfatase. To determine whether or not surfactants could reduce the MAC permeability barrier, the minimal inhibitory concentration (MIC) of antituberculosis drugs on MAC was determined in liquid medium with or without several kinds of surfactants including Tween 80. Five surfactants including Tween 80 increased the activity of antituberculosis drugs to MAC. These findings suggest that Tween 80 acts directly on the cell wall of MAC.     

A combination rapid and standard method for identification of Candida albicans

A medium consisting of an aqueous extract of zein, lactose, and Tween 80 is used together with an overlay of 1 % Tween 80 and coverslipping to provide a combined rapid (germ tube) and standard (chlamydospore) method for diagnosis ofCandida albicans. The method is exquisitely sensitive for diagnosis ofC. albicans but lumps chlamydospore-producing strains ofC. tropicalis withC. albicans.