<Emphasis Type="Italic">In vitro</Emphasis> minimum growth for conservation of <Emphasis Type="Italic">Drosophyllum lusitanicum</Emphasis>

The present paper reports a protocol for minimum growth conservation of Drosophyllum lusitanicum (L.) Link. in vitro. Double-node cuttings were maintained for 4, 8 and 12 months at 5 or 25 °C in the dark. The effects of sucrose either alone at 5, 20, 30, 40 and 60 g dm⁻³ or at 20, 40 and 60 g dm⁻³ in combination with 20 g dm⁻³ mannitol, on survival and post-storage shoot multiplication efficiency were investigated. The cultures could effectively be conserved under minimum growth at 5 °C for 8 months on Murashige and Skoog’s medium supplemented with 60 g dm⁻³ sucrose, 20 g dm⁻³ mannitol and 0.91 μM zeatin. Following extended conservation, the cultures could be successfully regenerated into new shoots, and they were morphologically similar to those of non-stored controls.     

<Emphasis Type="Italic">In vitro</Emphasis> propagation of <Emphasis Type="Italic">Chimonanthus praecox</Emphasis> (L.), a winter flowering ornamental shrub

A procedure for the micropropagation of Chimonanthus praecox (L) Link, wintersweet, has been developed using buds from adult trees excised in spring. Shoot cultures established on Murashige and Skoog (1962) medium supplemented with 0.5 mg l⁻¹ 6-benzyladenine (BAP) and 0.1 mg l⁻¹ indole-3-butyric acid (IBA) were difficult to maintain in vitro through extended periods of time due to browning of the medium, shoot and leaf necrosis, and hyperhydricity. A treatment combining the use of 0.1% w/v activated charcoal and addition of a double phase agar-solidified/liquid medium improved propagation, enabling a successful in vitro propagation scheme to be developed. Optimal shoot multiplication occurred on medium containing 0.5 mg l⁻¹ BAP, and rooting on medium with 2.0 mg l⁻¹ IBA for 7 d, followed by transfer to hormone-free medium. Rooted plantlets were easily acclimated in a glasshouse and replanted and cultured outdoors.     

Medium-term <Emphasis Type="Italic">in vitro</Emphasis> conservation of virus-free parthenocarpic tomato plants

Infection of field-maintained parthenocarpic Solanum lycopersicum L. (tomato) plants with Tomato yellow leaf curl virus provided the motivation to preserve the germplasm by in vitro methods. In this study, a method for medium-term in vitro conservation of parthenocarpic tomato plants was established. As a preliminary study, the non-parthenocarpic tomato ‘Momotaro’ was used to obtain a number of uniform explants for vegetative propagation under aseptic conditions at 23°C. The modification of sucrose or mannitol concentrations in the medium alone was insufficient for the slow-growth storage of shoot cultures. In contrast, temperature had a considerable effect on the time of conservation. ‘Momotaro’ shoot cultures were pre-cultured with Murashige and Skoog (MS) medium supplemented with 2% (w/v) sucrose at 23°C for 6 d for rooting and were then stored at 10°C for further conservation. When maintained at 10°C, only 27% of the shoot cultures needed subculture even after 3 mo, whereas 100% of plants needed subculturing after approximately 2 wk., when conserved at 23°C. When the same method was used with parthenocarpic tomatoes, plants were successfully conserved at 10°C without subculture for approximately 9 mo. Moreover, field performance and genetic stability of the stored tomato plants were assessed. This newly developed method allows for easy and efficient medium-term in vitro conservation to maintain virus-free parthenocarpic tomato plants.     

<Emphasis Type="Italic">In vitro</Emphasis> regeneration of mature <Emphasis Type="Italic">Pinus sylvestris</Emphasis> buds stored at freezing temperatures

Changes of morphogenic competence in mature P. sylvestris L. buds due to frozen storage were investigated. The highest callus formation was registered on explants stored at –18°C for three months, but on explants stored for five months, it was also higher than in the control. Budding and development of needles in vitro was observed only for buds frozen three to five months. Peroxidase activity was lowest in these buds. In contrast, polyphenol oxidase activity in bud tissues continually increased during frozen storage. Within 10 months of frozen storage the content of starch and sugars in resting buds changed. It may be concluded that changes in composition of non-structural sugars in pine buds after five months of frozen storage are part of metabolic changes leading to loss of morphogenic capacity.     

Development and <Emphasis Type="Italic">In Vitro</Emphasis>/<Emphasis Type="Italic">In Vivo</Emphasis> Evaluation of Etodolac Controlled Porosity Osmotic Pump Tablets

The aim of the current work was the design and evaluation of etodolac controlled porosity osmotic pump (CPOP) tablets exhibiting zero-order release kinetics. Variables influencing the design of (1) core tablets viz., (a) osmogent type (sodium chloride, potassium chloride, mannitol, and fructose) and (b) drug/osmogent ratio (1:0.25, 1:0.50, and 1:0.75), and (2) CPOP tablets viz., (a) coating solution composition, (b) weight gain percentage (1–5%, w/w), and (c) pore former concentration (5%, 10%, and 20%, v/v), were investigated. Statistical analysis and kinetic modeling of drug release data were estimated. Fructose-containing core tablets showed significantly (P < 0.05) more retarded drug release rates. An inverse correlation was observed between drug/fructose ratio and drug release rate. Coating of the optimum core tablets (F4) with a mixture of cellulose acetate solution (3%, w/v), diethyl phthalate, and polyethylene glycol 400 (85:10:5, v/v, respectively) till a 4% w/w weight gain enabled zero-order sustained drug delivery over 24 h. Scanning electron microscopy micrographs of coating membrane confirmed pore formation upon contact with dissolution medium. When compared to the commercial immediate-release Napilac® capsules, the optimum CPOP tablets (F4–34) provided enhanced bioavailability and extended duration of effective etodolac plasma concentration with minimum expected potential for side effects in healthy volunteers.KEY WORDS: cellulose acetate, controlled porosity osmotic pump, etodolac, osmogent, zero order     

Preparation and <Emphasis Type="Italic">In Vitro</Emphasis>/<Emphasis Type="Italic">In Vivo</Emphasis> Evaluation of Microparticle Formulations Containing Meloxicam

In this study, we have formulated chitosan-coated sodium alginate microparticles containing meloxicam (MLX) and aimed to investigate the correlation between in vitro release and in vivo absorbed percentages of meloxicam. The microparticle formulations were prepared by orifice ionic gelation method with two different sodium alginate concentrations, as 1% and 2% (w/v), in order to provide different release rates. Additionally, an oral solution containing 15 mg of meloxicam was administered as the reference solution for evaluation of in vitro/in vivo correlation (ivivc). Following in vitro characterization, plasma levels of MLX and pharmacokinetic parameters [elimination half-life (t _1/2), maximum plasma concentration (C _max), time for C _max (t _max)] after oral administration to New Zealand rabbits were determined. Area under plasma concentration–time curve (AUC_0–∞) was calculated by using trapezoidal method. A linear regression was investigated between released% (in vitro) and absorbed% (in vivo) with a model-independent deconvolution approach. As a result, increase in sodium alginate content lengthened in vitro release time and in vivo t _max value. In addition, for ivivc, linear regression equations with r ² values of 0.8563 and 0.9402 were obtained for microparticles containing 1% and 2% (w/v) sodium alginate, respectively. Lower prediction error for 2% sodium alginate formulations (7.419 ± 4.068) compared to 1% sodium alginate formulations (9.458 ± 5.106) indicated a more precise ivivc for 2% sodium alginate formulation.     

<Emphasis Type="Italic">CDPK</Emphasis> gene expression in somatic embryos of <Emphasis Type="Italic">Panax ginseng</Emphasis> expressing <Emphasis Type="Italic">rolC</Emphasis>

A somatic embryogenesis protocol for plant regeneration of northern red oak (Quercus rubra) was established from immature cotyledon explants. Embryogenic callus cultures were induced on Murashige and Skoog medium (MS) containing 3% sucrose, 0.24% Phytagel™, and various concentrations of 2,4-dichlorophenoxyacetic acid (2,4-d) after 4 weeks of culture in darkness. A higher response (66%) of embryogenic callus was induced on 0.45 μM 2,4-d. Higher numbers of globular- (31), heart- (17), torpedo- (12), and cotyledon-stage (8) embryos per explant were obtained by culturing embryogenic callus on MS with 3% sucrose, 0.24% Phytagel™, and devoid of growth regulators after 8 weeks culture in darkness. Continuous sub-culturing of embryogenic callus on medium containing 2,4-d yielded only compact callus. Desiccation of embryos for 3 days in darkness at 25 ± 2°C followed by cold storage at 4°C in darkness for 8 weeks favored embryo germination and development of plantlets. Cotyledon-stage embryos subjected to desiccation and chilling treatment cultured on MS with 3% sucrose, 0.24 Phytagel™, 0.44 μM 6-benzylaminopurine (BA), and 0.29 μM gibberellic acid germinated at a higher frequency (61%) than with 0.44 μM BA alone and control cultures. Germinated plantlets developed a shoot and root, were acclimatized successfully, and maintained in a growth room for plantlet development.     

Prospects of androgenetic induction in <Emphasis Type="Italic">Lupinus</Emphasis> spp.

Anthers cultures of six Polish cultivars of pasture lupin (Lupinus L.) were examined for their androgenic response. Anthers with microspores at the uninucleate stage were isolated from flower buds and cultured in liquid media. Better viability of androgenetic structures was obtained when donor plants had grown under field as opposed to greenhouse conditions. A density of five anthers per 0.5 ml medium was more conducive to androgenetic induction than 25 anthers per 0.5 ml medium. Addition of 5% maltose to the induction medium and culture at 25°C without pre-treatment of flowers, buds or anthers promoted microspore release and division. The greatest frequency of androgenic callus, ~70% was developed from cvs. Katon, Wat (white lupin), in contrast to cvs. Legat, Juno (yellow lupin), Polonez and Sonet (narrow-leafed lupin) with callus induction ~30–40%. Despite various combinations of media tested, plant regeneration was not obtained from anther derived callus.     

Sporulation and regeneration efficiency of phosphobacteria (<Emphasis Type="Italic">Bacillus megaterium</Emphasis> var <Emphasis Type="Italic">phosphaticum</Emphasis>)

Sporulation in Bacillus megaterium var phosphaticum (PB — 1) was induced using modified nutrient media. This modified medium induced sporulation within 36 h. After spore induction the spores were kept under refrigerated (5°C) and room temperature (32°C) for five months and survival of spores was studied at 15 days intervals by plating them in nutrient agar medium. It was observed that there was not much variation in the storage temperature (5°C & 32°C). The spore cells of Bacillus megaterium var phosphaticum (PB — 1) were observed up to five months of storage under refrigerated (5°C) and room temperature (32°C). Regeneration of spore cells into vegetative cells was studied in tap water, rice gruel, nutrient broth, sterile lignite and sterile water at different concentrations of spore inoculum. The multiplication of sporulated Bacillus megaterium var phosphaticum culture was fast and reached its maximum (29.5 × 10⁸ cfu ml⁻¹) in nutrient broth containing 5 per cent inoculum level.     

<Emphasis Type="Italic">Thermotoga maritima</Emphasis> TM0298 is a highly thermostable mannitol dehydrogenase

Thermotoga maritima TM0298 is annotated as an alcohol dehydrogenase, yet it shows high identity and similarity to mesophilic mannitol dehydrogenases. To investigate this enzyme further, its gene was cloned and expressed in Escherichia coli. The purified recombinant enzyme was most active on fructose and mannitol, making it the first known hyperthermophilic mannitol dehydrogenase. T. maritima mannitol dehydrogenase (TmMtDH) is optimally active between 90 and 100 °C and retains 63% of its activity at 120 °C but shows no detectable activity at room temperature. Its kinetic inactivation follows a first-order mechanism, with half-lives of 57 min at 80 °C and 6 min at 95 °C. Although TmMtDH has a higher V _max with NADPH than with NADH, its catalytic efficiency is 2.2 times higher with NADH than with NADPH and 33 times higher with NAD⁺ than with NADP⁺. This cofactor specificity can be explained by the high density of negatively charged residues (Glu193, Asp195, and Glu196) downstream of the NAD(P) interaction site, the glycine motif. We demonstrate that TmMtDH contains a single catalytic zinc per subunit. Finally, we provide the first proof of concept that mannitol can be produced directly from glucose in a two-step enzymatic process, using a Thermotoga neapolitana xylose isomerase mutant and TmMtDH at 60 °C.     

<Emphasis Type="Italic">Narcissus</Emphasis> bulblet formation <Emphasis Type="Italic">in vitro</Emphasis>: effects of carbohydrate type and osmolarity of the culture medium

Shoot clump cultures of Narcissus cultivars St. Keverne and Hawera were used to investigate the effects of culture medium carbon supply, type of carbohydrate and osmolarity on in vitro bulblet development. Increasing the medium osmolarity using mannitol or sorbitol, which did not act as substrates for growth, failed to stimulate bulblet formation with either cultivar. An exception to this was a relatively small increase in total bulblet dry weight per culture, in the cultivar Hawera only, caused by adding 30 g l ^–1 sorbitol in combination with 30 g l^–1 sucrose. Simultaneously increasing the medium osmolarity and carbon supply using the metabolisable carbohydrate sources, sucrose, glucose, fructose or an equimolar mixture of glucose and fructose stimulated bulblet production, total dry matter accumulation and partitioning into bulblets. At comparable levels of carbon supply up to 19.0 g l^–1, bulblet development of both cultivars was similar with monosaccharide and sucrose media. This indicates that substrate supply is more important for bulblet development than osmolarity of the culture medium. The cultivar Hawera also showed similar responses to monosaccharide and sucrose media supplying 37.9 g C l^–1, despite the high osmolarity of monosaccharide media (c. 650 m Osm kg^–1, equivalent to –1.6 MPa, compared to 380 m Osm kg^–1 for sucrose medium). However in St. Keverne total dry matter accumulation and dry weight per bulblet were further stimulated only by increasing the sucrose supply from 19.0 to 37.9 g C l^–1, not by increasing the monosaccharide supply. Implications of the findings for Narcissus micropropagation are discussed.     

Cloning,Expression and Purification of <Emphasis Type="Italic">Microcystis viridis</Emphasis> Lectin in <Emphasis Type="Italic">Escherichia coli</Emphasis>

Microcystis viridis lectin (MVL), a sugar-binding protein originally isolated from freshwater blue-green algae Microcystis viridis, has been reported to have potent anti-HIV activity. In this paper, we described the expression and purification of recombinant-MVL (R-MVL) gene in E. coli. The results demonstrated that the R-MVL in shake flask cultures was primarily expressed either in the form of inclusion bodies at 37°C or in the soluble fraction at 23 °C. Secondly, a one-step purification based on nickel-affinity chromatography was employed and 15 mg of highly purified (>95%) R-MVL from 1 l of cell cultures was yielded. The purified R-MVL was then subjected to MALDI-TOF–MS analysis for protein identification. In conclusion, for the first time, the R-MVL was successfully cloned and expressed in E. coli, which is useful for further study and large-scale cost-effective production of MVL protein.     

Diagnostic properties of three conventional selective plating media for selection of <Emphasis Type="Italic">Bacillus cereus</Emphasis>, <Emphasis Type="Italic">B. thuringiensis</Emphasis> and <Emphasis Type="Italic">B. weihenstephanensis</Emphasis>

The aim of this study was to assess the diagnostic properties of the two selective plating media and a chromogenic medium for identification of Bacillus cereus. The 324 isolates were B. cereus (37%), Bacillus weihenstephanensis (45%) or Bacillus thuringiensis (18%), as identified by a new combination of techniques. All isolates were growing on mannitol–egg yolk–polymyxin agar (MYP), and they did not form acid from mannitol. However, a significant lower number of B. thuringiensis isolates did not show lecithinase activity. All isolates were also growing on polymyxin–egg yolk–mannitol–bromothymol blue agar (PEMBA); however, 11% isolates indicated that they did produce acid from mannitol, and 15% isolates did not show any lecithinase activity. Five of the isolates did not grow at all on the chromogenic agar, and 14 of the growing isolates were β-glucosidase negative. It is concluded that the two recommended selective plating media MYP and PEMBA for detection of B. cereus group bacteria both have their limitations for identification of some B. cereus, B. weihenstephanensis or B. thuringiensis. However, MYP is preferable compared to PEMBA. The chromogenic medium has its own advantages and limitations, and some of the limitations seem to be solved by incubation at 30°C instead of the recommended 37°C.     

An improved method of cell culture system from eye stalk,hepatopancreas, muscle,ovary, and hemocytes of <Emphasis Type="Italic">Penaeus vannamei</Emphasis>

Improved methods of cell culture from eye stalk, hepatopancreas, muscle, ovary, and hemocytes of shrimp (Penaeus vannamei) were established using synthetic media and shrimp muscle extract (SME). For hemocytes and ovarian cell cultures, Grace’s insect medium supplemented with 10% (v/v) fetal bovine serum and 10% SME (v/v) showed enhanced attachment and proliferation of the cells. The hemocyte and ovarian cell cultures could be maintained for 48 and 66 days, respectively, and have been sub-cultured four and six times, respectively. Both ovary and hemocyte cell cultures contained primarily epithelial-like cells. Cells derived from ovary tissue grew preferably between 26°C and 28°C with 5% CO₂. Although the temperature preference of hemocyte cells was the same as ovarian cells, CO₂ supplementation did not show any difference in the growth of hemocyte cells. When the shrimp were injected with lipopolysaccharide (8 μg/g of shrimp) and hemolymph was drawn 24 h post-injection, the in vitro multiplicity of hemocytes dramatically improved. The growth of eye stalk, hepatopancreas, and muscle-derived cells was much less compared to ovarian cells and hemocytes under the conditions described above. The optimal culture conditions for ovarian cells and hemocytes were also different from that for eye stalk, hepatopancreas, and muscle cell culture. The proliferation efficiencies of primary cultures of hepatopancreas, eyestalk, and muscle cells were about 30, 12, and <7 d, respectively. The improved culture conditions described here, particularly for hemocytes and ovary, will be very useful for in vitro studies involving viruses infecting shrimp and in shrimp genomic studies.     

Subcellular concentrations of sugar alcohols and sugars in relation to phloem translocation in <Emphasis Type="Italic">Plantago major,Plantago maritima</Emphasis>, <Emphasis Type="Italic">Prunus persica</Emphasis>, and <Emphasis Type="Italic">Apium graveolens</Emphasis>

Sugar and sugar alcohol concentrations were analyzed in subcellular compartments of mesophyll cells, in the apoplast, and in the phloem sap of leaves of Plantago major (common plantain), Plantago maritima (sea plantain), Prunus persica (peach) and Apium graveolens (celery). In addition to sucrose, common plantain, sea plantain, and peach also translocated substantial amounts of sorbitol, whereas celery translocated mannitol as well. Sucrose was always present in vacuole and cytosol of mesophyll cells, whereas sorbitol and mannitol were found in vacuole, stroma, and cytosol in all cases except for sea plantain. The concentration of sorbitol, mannitol and sucrose in phloem sap was 2- to 40-fold higher than that in the cytosol of mesophyll cells. Apoplastic carbohydrate concentrations in all species tested were in the low millimolar range versus high millimolar concentrations in symplastic compartments. Therefore, the concentration ratios between the apoplast and the phloem were very strong, ranging between 20- to 100-fold for sorbitol and mannitol, and between 200- and 2000-fold for sucrose. The woody species, peach, showed the smallest concentration ratios between the cytosol of mesophyll cells and the phloem as well as between the apoplast and the phloem, suggesting a mixture of apoplastic and symplastic phloem loading, in contrast to the herbal plant species (common plantain, sea plantain, celery) which likely exhibit an active loading mode for sorbitol and mannitol as well as sucrose from the apoplast into the phloem.     

<Emphasis Type="Italic">In vitro</Emphasis> propagation of <Emphasis Type="Italic">Zingiber petiolatum</Emphasis> (Holttum)

Summary We describe an in vitro propagation protocol for Zingiber petiolatum (Holttum), I. Theilade, a rare species from the southern part of Thailand. Fruits were surface-sterilized and seeds germinated on Murashige and Skoog medium (MS) medium supplemented with 3% sucrose. Three-month-old seedlings were used as initial plant material for in vitro propagation. Terminal buds of the plants were inoculated on MS medium containing 6-benzylaminopurine (BA; 2.2–35.5 μM) alone or in combination with 1-naphthaleneacetic acid (0.5 μM). Eight weeks after inoculation, the cultures were transferred to MS medium without plant growth regulators for 4wk. The cultures transferred from MS medium with 17.8 μM BA revealed the highest shoot induction rate of 6.1±0.7 shoots per explant. Rooting was spontaneously achieved in MS medium without plant growth regulators. Rooted plants were successfully transplanted to soil.     

Physiological implication of intracellular trehalose and mannitol changes in response of entomopathogenic fungus <Emphasis Type="Italic">Beauveria bassiana</Emphasis> to thermal stress

To explore possible role of intracellular trehalose accumulation in fungal tolerance to summer-like thermal stress, 3-day colonies of Beauveria bassiana grown on a glucose-free medium at 25°C were separately exposed to 35, 37.5 and 40°C for 1–18 h, respectively. Trehalose accumulation in stressed mycelia increased from initial 4.2 to 88.3, 74.7 and 65.5 mg g⁻¹ biomass after 6-h stress at 35, 37.5 and 40°C, respectively, while intracellular mannitol level generally declined with higher temperatures and longer stress time. The stress-enhanced trehalose level was significantly correlated to decreased trehalase activity (r ² = 0.73) and mannitol content (r ² = 0.38), which was inversely correlated to the activity of mannitol dehydrogenase (r ² = 0.41) or mannitol 1-phosphate dehydrogenase (r ² = 0.30) under the stresses. All stressed cultures were successfully recovered at 25°C but their vigor depended on stressful temperature, time length and the interaction of both (r ² = 0.98). The highest level of 6-h trehalose accumulation at 35°C was found enhancing the tolerance of the stressed cultures to the greater stress of 48°C. The results suggest that the trehalose accumulation result partially from metabolized mannitol and contribute to the fungal thermotolerance. Trehalase also contributed to the thermotolerance by hydrolyzing accumulated trehalose under the conditions of thermal stress and recovery.     

Edible oil degradation by using yeast coculture of <Emphasis Type="Italic">Rhodotorula pacifica</Emphasis> ST3411 and <Emphasis Type="Italic">Cryptococcus laurentii</Emphasis> ST3412

To develop a microbial treatment of edible oil-contaminated wastewater, microorganisms capable of rapidly degrading edible oil were screened. The screening study yielded a yeast coculture comprising Rhodotorula pacifica strain ST3411 and Cryptococcus laurentii strain ST3412. The coculture was able to degrade efficiently even at low contents of nitrogen ([NH₄–N] = 240 mg/L) and phosphorus sources ([PO₄–P] = 90 mg/L). The 24-h degradation rate of 3,000 ppm mixed oils (salad oil/lard/beef tallow, 1:1 w/w) at 20°C was 39.8% ± 9.9% (means ± standard deviations of eight replicates). The highest degradation rate was observed at 20°C and pH 8. In a scaled-up experiment, the salad oil was rapidly degraded by the coculture from 671 ± 52.0 to 143 ± 96.7 ppm in 24 h, and the degradation rate was 79.4% ± 13.8% (means ± standard deviations of three replicates). In addition, a repetitive degradation was observed with the cell growth by only pH adjustment without addition of the cells.     

Ethanol induces calcium influx via the Cch1-Mid1 transporter in <Emphasis Type="Italic">Saccharomyces</Emphasis><Emphasis Type="Italic">cerevisiae</Emphasis>

Yeast suffers from a variety of environmental stresses, such as osmotic pressure and ethanol produced during fermentation. Since calcium ions are protective for high concentrations of ethanol, we investigated whether Ca²⁺ flux occurs in response to ethanol stress. We find that exposure of yeast to ethanol induces a rise in the cytoplasmic concentration of Ca²⁺. The response is enhanced in cells shifted to high-osmotic media containing proline, galactose, sorbitol, or mannitol. Suspension of cells in proline and galactose-containing media increases the Ca²⁺ levels in the cytoplasm independent of ethanol exposure. The enhanced ability for ethanol to induce Ca²⁺ flux after the hypertonic shift is transient, decreasing rapidly over a period of seconds to minutes. There is partial recovery of the response after zymolyase treatment, suggesting that cell wall integrity affects the ethanol-induced Ca²⁺ flux. Acetate inhibits the Ca²⁺ accumulation elicited by the ethanol/osmotic stress. The Ca²⁺ flux is primarily via the Cch1 Ca²⁺ influx channel because strains carrying deletions of the cch1 and mid1 genes show greater than 90% reduction in Ca²⁺ flux. Furthermore, a functional Cch1 channel reduced growth inhibition by ethanol.     

Effect of temperature on <Emphasis Type="SmallCaps">d</Emphasis>-arabitol production from lactose by <Emphasis Type="Italic">Kluyveromyces lactis</Emphasis>

d-Arabitol production from lactose by Kluyveromyces lactis NBRC 1903 has been studied by following the time courses of concentrations of cell mass, lactose, d-arabitol, ethanol, and glycerol at different temperatures. It was found that temperature is a key factor in d-arabitol production. Within temperatures ranging from 25 to 39°C, the highest d-arabitol concentration of 99.2 mmol l⁻¹ was obtained from 555 mmol l⁻¹ of lactose after 120 h of batch cultivation at 37°C. The yield of d-arabitol production on cell mass growth increased drastically at temperatures higher than 35°C, and the yield reached 1.07 at 39°C. Increasing the cell mass concentration two-fold after 24 h of culture growth at 37°C, the d-arabitol concentration further increased to 168 mmol l⁻¹. According to the distribution of the metabolic products, metabolic changes related to growth phase were also discussed. The stationary-phase K. lactis cells in the batch culture that is started with exposing the precultured inoculum to high osmotic stress, high oxidative stress, and high heat stress are found to be preferable for d-arabitol production.