Production of 4-Keto-D-arabonate by Oxidative Fermentation with Newly Isolated Gluconacetobacter liquefaciens

Production of 4-keto-D-arabonate (4KAB) was confirmed in a culture medium of Gluconacetobacter liquefaciens strains, newly isolated from water kefir in Argentina. The strains rapidly oxidized D-glucose, D-gluconate (GA), and 2-keto-D-gluconate (2KGA), and accumulated 2,5-diketo-D-gluconate (25DKA) exclusively before reaching the stationary phase. 25DKA was in turn converted to 4KAB, and 4KAB remained stable in the culture medium. The occurrence of 4KAB was assumed by Ameyama and Kondo about 50 years ago in their study on the carbohydrate metabolism of acetic acid bacteria (Bull. Agr. Chem. Soc. Jpn., 22, 271–272, 380–386 (1958)). This is the first report confirming microbial production of 4KAB.     

Isolation and initial characterization of the tellurite reducing moderately halophilic bacterium, Salinicoccus sp. strain QW6

Among the 49 strains of moderately halophilic bacteria isolated from the salty environments of Iran, a Gram-positive coccus designated as strain QW6 showed high capacity in the removal of toxic oxyanions of tellurium in a wide range of culture medium factors including pH (5.5-10.5), temperature (25-45 degrees C), various salts including NaCl, KCl, and Na(2)SO(4) (0.5-4M), selenooxyanions (2-10mM), and at different concentrations of potassium tellurite (0.5-1mM) under aerobic condition. Phenotypic characterization and phylogenetic analyses based on 16S rDNA sequence comparisons indicated that this strain was a member of the genus Salinicoccus. The maximum tellurite removal was exhibited in 1.5M NaCl at 35 degrees C, while the activity reduced by 53% and 47% at 25 and 45 degrees C, respectively. The optimum pH for removal activity was shown to be 7.5, with 90% and 83% reduced removal capacities at the two extreme values of 5.5 and 10, respectively. The impact of different concentrations of selenooxyanions (2-10mM) on tellurite removal by strain QW6 was evaluated. The ability of strain QW6 in the removal of tellurite in the presence of 6mM selenite increased by 25%. The concentration of toxic potassium tellurite in the supernatant of the bacterial culture medium decreased by 99% (from 0.5 to 0.005mM) after 6 days and the color of the medium changed to black due to the formation of less toxic elemental tellurium.     

Immunochemical analysis of trichothecenes produced by various fusaria

The production of type A trichothecene mycotoxins by 19 Fusaria, including 12Fusarium sporotrichioides, 4F. chlamydosporum and 3F. graminearum at 15°C and 25°C over a 35-day period was analyzed by ELISA using antibodies cross-reactive with most type A trichothecenes after conversion to T-2 tetraol tetraacetate. The toxin production peaked at 20–25 days of incubation with maximum yield between 4–6 mg type A trichothecene/ml of culture medium for 5F. sporotrichioides cultures and between 1 to 2 mg/ml for 6F. sporotrichioides cultures. OneF. sporotrichioides produced 700 µg type A trichothecenes/ml of culture medium. Detectable type A trichothecene was also found in the culture extracts ofF. chlamydosporum andF. graminearum, but the yield was very low (less than 100 µg/ml). Quantitative determination of individual trichothecenes was achieved by separation of different toxin in HPLC and followed by ELISA analysis. Eight to 10 immunoreactive peaks, corresponding to various type A trichothecenes, were detected in all the fungal extracts. T-2 tetraol (T-2-4ol), 4-acetyl-T-2 tetraol (4-Ac-T-2-4ol), neosolaniol (NEOS), diacetoxyscirpenol (DAS), HT-2 and T-2 toxin accounted for more than 85% of the total toxins. In general, low temperature was preferred for total type A trichothecene production. More T-2-4ol, 4-Ac-T-2-4ol, HT-2 and DAS were produced at 25°C. In contrast, more T-2 toxin and NEOS were produced at 15°C. Transformation of T-2 toxin and NEOS to polar metabolites such as T-2-4ol, 4-acetyl-T-2-4ol and HT-2 by various strains were observed at both temperatures after 25 days incubation.     

Degradation of 4-aminobenzenesulfonate by a two-species bacterial coculture

The mutualistic interactions in a 4-aminobenzenesulfonate (sulfanilate) degrading mixed bacterial culture were studied. This coculture consisted of Hydrogenophaga palleronii strain S1 and Agrobacterium radiobacter strain S2. In this coculture only strain S1 desaminated sulfanilate to catechol-4-sulfonate, which did not accumulate in the medium but served as growth substrate for strain S2. During growth in batch culture with sulfanilate as sole source of carbon, energy, nitrogen and sulfur, the relative cell numbers (colony forming units) of both strains were almost constant. None of the strains reached a cell number which was more than threefold higher than the cell number of the second strain. A mineral medium with sulfanilate was inoculated with different relative cell numbers of both strains (relative number of colony forming units S1:S2 2200:1 to 1:500). In all cases, growth was found and the proportion of both strains moved towards an about equal value of about 3:1 (strain S1:strain S2). In contrast to the coculture, strain S1 did not grow in a mineral medium in axenic culture with 4-aminobenzenesulfonate or any other simple organic compound tested. A sterile culture supernatant from strain S2 enabled strain S1 to grow with 4-aminobenzenesulfonate. The same growth promoting effect was found after the addition of a combination of 4-aminobenzoate, biotin and vitamin B₁₂. Strain S1 grew with 4-aminobenzenesulfonate plus the three vitamins with about the same growth rate as the mixed culture in a mineral medium. When (resting) cells of strain S1 were incubated in a pure mineral medium with sulfanilate, up to 30% of the oxidized sulfanilate accumulated as catechol-4-sulfonate in the culture medium. In contrast, only minor amounts of catechol-4-sulfonate accumulated when strain S1 was grown with 4ABS in the presence of the vitamins.Abbreviations 4ABS 4-aminobenzenesulfonate - CFU colony forming units - 4CS catechol-4-sulfonate - 4HB 4-hydroxybenzoate     

Evaluation of hydrophobic properties of Yersinia enterocolitica strains isolated from humans and pigs]

The aim of the study was to evaluate the hydrophobic properties of Yersinia enterocolitica and to determine the influence of the culture conditions, such as: type of medium, temperature, and duration of the culture on the manifestation of these properties. The subject of the study were 117 of Y. enterocolitica strains isolated from humans and pigs. The ammonium sulphate salt aggregation test according to Lindahl modified method was used to evaluate the hydrophobic properties of Y. enterocolitica strains. Strains of Y. enterocolitica were cultured for 24 h at 25 degrees C on TSA (Difco) medium. During investigation of the influence of the culture conditions the chosen strains were incubated for 24 h and 48 h at 25 degrees C and 37 degrees C on TSA (Difco), LB (Difco), enrichment agar (Biomed), and enrichment agar with 5% sheep blood (Graso). A total of 44.5%, 17.9%, 9.4%, and 28.2% strains of Y. enterocolitica showed very strong hydrophobic properties, strong hydrophobic properties, some hydrophobic properties, and were non-hydrophobic, respectively when strains of Y. enterocolitica were cultured for 24 h at 25 degrees C on TSA medium. A total of 75.5% strains isolated from humans showed very strong hydrophobic properties and 13.5% strains were non-hydrophobic. Among strains isolated from pigs 30% showed very strong hydrophobic properties but 35% were non-hydrophobic. The hydrophobic properties of Y. enterocolitica depended on the temperature, duration of the culture and the type of media. The highest number of strains with very strong hydrophobic properties (89.6%) was obtained after 48 h of the incubation at 37 degrees C on the enrichment agar with 5% sheep blood. The highest number of non-hydrophobic strains of Y. enterocolitica (28.5%) was obtained after 24 h at 25 degrees C on TSA medium.     

Isolation of Dunaliella spp. from a hypersaline lake and their ability to accumulate glycerol

The purpose of the present work was to study the potential biotechnological use of Dunaliella species isolated from a hypersaline lake in Turkey. Dunaliella spp. grown in Johnson's medium were isolated and their glycerol production was studied in a batch system in order to determine the optimal conditions required for the highest glycerol accumulation. In the experiments performed with four newly isolated Dunaliella spp., the maximum glycerol accumulation was obtained at 20% NaCl concentration, and pH 6 (for strains T1 and T2) and pH 9 (for strains T3 and T4). Biomass production by strain T2 was significantly higher that by the other strains but the highest glycerol production in broth was obtained by strain T1 followed by strain T2. Strain T1 showed high glycerol production, i.e. 452.57microg/ml of culture broth at 20% NaCl concentration. The highest glycerol accumulation on both dry weight and cell basis was obtained with strain T1, followed by strains T3 and T4 (55.01, 50.16, and 40.23microg/10(6) cells (or pg/cell), respectively) at 25% NaCl concentration. When the high initial inoculum concentration was used at 25% NaCl concentration, strain T1 had the shortest (approximately 10-15days) lag period. This study shows that the isolated strains T1 and T2 can be used for glycerol production because of their high productivity.     

Rat mammary preadipocytes in culture produce a trophic agent for mammary epithelia-prostaglandin E2

Cell strains and cell lines rat mammary (Rama) 350-353 have been isolated from the slowly adherent stromal fraction of enzymatically digested rat mammary glands. Primary cultures of this fraction yield fat cels on extended culture. Their proportion can be increased with horse serum or growth hormone in the medium, and this increase is associated with a 100-fold or more increase in the release of radioimmunoassayable prostaglandins of the E type (PGE). The stromal cell strains and lines that are capable of yielding fat cells also secrete elevated levels (greater than 100 ng/mg/24 hr) of PGE; the fast-sticking epithelial fraction in primary cultures and the epithelial cell lines derived from it secrete 10-100 times less. Chromatography and radioisotopic labeling of the culture media from Rama 352 cells identify the PG as PGE2. PGE2 with insulin and hydrocortisone maximally stimulates [3H]DNA synthesis of epithelial cell lines and primary cultures from normal and tumorous glands by 2-4-fold at concentrations (10-20 ng/ml) well below those released by the preadipocytic stromal cells (20-100 ng/ml). Medium exposed to most cultured cells stimulates [3H]DNA synthesis of one epithelial cell line, Rama 25, by 2-4-fold. Prevention of the synthesis of PGE2 in Rama 352 cultures with indomethacin or flurbiprofen abolishes the mitogenic activity present in the culture medium, and the PG receptor antagonist polyphloretin phosphate inhibits completely the mitogenic activity for Rama 25 cells. Myoepithelial-like cell lines normally secrete moderate levels of PGE (10-100 ng/mg/24 hr) but the mitogenic activity for Rama 25 cells released from one such line, Rama 29, is not abolished by preventing the synthesis of PG's nor by PG-receptor antagonists.     

Genetic analysis of the 6-thiobenzylpurine binding site of the nucleoside transporter in mouse lymphoblasts

From a mutagenized population of wild-type S49 T lymphoblasts, cells were selected for their ability to survive in semisolid medium containing 0.5 mM hypoxanthine, 0.4 microM methotrexate, 30 microM thymidine, 30 microM deoxycytidine, and 30 microM p-nitrobenzyl-6-thioinosine (NBMPR), a potent inhibitor of nucleoside transport. Unlike wild-type parental cells, two mutant clones, KAB1 and KAB5, were still sensitive to nucleoside-mediated cytotoxicity in the presence of NBMPR. Comparisons of the abilities of wild-type cells, KAB1, and KAB5 cells to incorporate exogenous nucleoside to the corresponding nucleoside triphosphate indicated that nucleoside incorporation was much less sensitive to inhibition by NBMPR in the mutant cells. Rapid transport studies indicated that the mutant cell lines, unlike the wild-type parent, had acquired an NBMPR-insensitive nucleoside transport component which was similar to the NBMPR-sensitive wild-type transporter with respect to affinities for nucleosides and sensitivities toward N-ethylmaleimide and dipyridamole. Binding studies with [3H]NBMPR indicated that KAB5 cells were 70-75% deficient in the number of NBMPR binding sites, whereas KAB1 cells possessed a wild-type complement of NBMPR binding sites with wild-type binding characteristics. These data suggest that the NBMPR binding site in wild-type S49 cells is genetically distinguishable from the nucleoside carrier site and that the former may be a regulatory site.     

Formation of 2-hydroxy-4-methylpentanoic acid from l-leucine by Clostridium butyricum

Abstract Five Clostridium butyricum strains of different origin were grown in trypticase-yeast extract-hemin medium with or without d-glucose (TGYH or TYH medium, respectively) and in a synthetic basal medium with d-glucose (BMG medium). 2-Hydroxy-4-methylpentanoic acid was detected by gas chromatography-mass spectrometry (GC-MS) for the five strains whether grown in TGYH or TYH medium (270 or 170 μM, respectively). In BMG medium supplemented with l-leucine (10 mM), the concentration of this metabolite was strongly increased (2.8 mM versus 10 μM in the control). After culture in TGYH or TYH medium supplemented with l-( methyl -²H₃)leucine, 2-hydroxy-4-([²H₃]methyl)pentanoic acid was detected by GC-MS. This observation demonstrates that C. butyricum is able to convert l-leucine into the corresponding 2-hydroxy acid and opens a new aspect in the study of C. butyricum metabolism.     

培养条件对头孢霉菌丝体脂肪酸组分的影响

研究了头孢霉(Cephalosporium sp.)菌丝体最大生产力和多不饱和脂肪酸形成积累的条件。菌丝体最适培养条件为：麦芽糖60g/L\,KNO33g/L、起始pH为60、500mL三角瓶装100mL培养基、接种25%、25℃培养10d则菌丝体达到最大干重。多不饱和脂肪酸形成积累的最适条件为：葡萄糖10～20g/L、(NH4)2SO4或NH4Cl 3g/L、培养基起始pH为40、500mL三角瓶装100mL培养基、接种10%～20%、10℃下照光培养。〖JP2〗因此,在整个生产流程中可采用不同条件分段掌握的技术原则。同时提出在多不饱和脂肪酸的形成和积累途径中油酸(18∶1)向亚油酸(18∶2)的转化是关键,为进一步探索最适培养条件和关键酶的调节提供依据。     

Changes of methicillin-resistant Staphylococcus aureus (MRSA) phagotypes in Gdansk in 1990-1998

The aim of the study was the assessment of changes in the occurrence of various MRSA phagotypes in hospitals in the Gdańsk area in 1990-1998. The study was carried out on 175 MRSA strains: 45 strains isolated in 1990-1995 and 130 in 1997-1998. The studied staphylococci were obtained from various clinical materials from patients in 18 hospitals. Phagotyping was done with a set of 10 experimental phages from MRSA strains obtained from the Central Public Health Laboratory in London. Drug-resistance was determined by the disc-diffusion method and in case of strains with medium susceptibility to fusidic acid the minimal inhibitory concentration (MIC) was determined by serial dilutions on solid medium. The study showed among MRSA strains isolated in 1997-1998 a new, previously not known strains with phage pattern MR25/M5 predominated (57.7%). Its presence was found in various hospitals in that area. MRSA belonging to MR25/M5 phagotype were mostly resistant to doxycycline, gentamycin, erythromycin, clindamycin, ciprofloxacin, rifampicin and were resistant or only had medium susceptibility to fusidic acid. The MIC values for strains with medium susceptibility to fusidic acid (4-8 micrograms/ml) showed an evident decrease of the susceptibility to this antibiotic, formerly common in MRSA. At the same time, in 1997-1998 a considerable decrease was observed of the number of MRSA strains belonging to MR8/MR12/MR25/30/33/38/M5/622 phagotype (from 31.1% to 0.8%), and disappearance of strains with phagotypes MR25/56B/M3 and MR8/MR25/622, which in 1990-1995 accounted for 15.6% of the studied staphylococci.     

Production of both prolactin and growth hormone by clonal strains of rat pituitary tumor cells. Differential effects of hydrocortisone and tissue extracts

Several established clonal strains of rat pituitary cells which produce growth hormone in culture have been shown to secrete a second protein hormone, prolactin. Prolactin was measured immunologically in culture medium and within cells by complement fixation. Rates of prolactin production varied from 6.6 to 12 µg/mg cell protein per 24 hr in four different cell strains. In these cultures ratios of production of prolactin to growth hormone varied from 1.0 to 4.1. A fifth clonal strain produced growth hormone but no detectable prolactin. Intracellular prolactin was equivalent to the amount secreted into medium in a period of about 1–2 hr. Both cycloheximide and puromycin suppressed prolactin production by at least 94%. Hydrocortisone (3 x 10^-6 M), which stimulated the production of growth hormone 4- to 8-fold in most of the cell strains, reduced the rate of prolactin production to less than 25% of that in control cultures. Conversely, addition of simple acid extracts of several tissues, including hypothalamus, to the medium of all strains increased the rate of production of prolactin six to nine times and decreased growth hormone production by about 50%. We conclude that multifunctional rat pituitary cells in culture show unusual promise for further studies of the control of expression of organ-specific activities in mammalian cells.     

Physiological characteristics of the strains of Cryptococcus deffluens--producers of penicillin acylase]

A fermentation medium balanced by the main components was developed for Cryptococcus diffluens strains producing penicillin-V-acylases (PA). It was shown that the culture needed for production of the enzyme was inductor, which was phenoxyacetic acid (POAA). Additional introduction of ethanol to the medium provided an increase in production of PA by 36 per cent and the culture growth by 25 per cent. Introduction of one of the following substances to the medium with POAA and ethanol i.e. (CN3COO)2Ca, FeSO4, proline or asparagine provided an additional increase in the production level of PA by 24 to 94 per cent. The use of the medium varieties will permit one to isolate highly productive cells of the culture.     

Altered nucleoside transporters in mammalian cells selected for resistance to the physiological effects of inhibitors of nucleoside transport

From a mutagenized population of wild type S49 T lymphoma cells, clones were generated that were resistant to the physiological effects of the potent inhibitor of nucleoside transport, 4-nitrobenzyl-6-thioinosine (NBMPR). These cells were selected for their ability to survive in semisolid medium containing 0.5 mM hypoxanthine, 0.4 microM methotrexate, 30 microM thymidine, 30 microM deoxycytidine, in the presence of 30 microM NBMPR. NBMPR protected wild type cells from the effects of a spectrum of cytotoxic nucleosides, whereas two mutant clones, KAB1 and KAB5, were still sensitive to nucleoside-mediated cytotoxicity in the presence of NBMPR. Comparisons of the abilities of wild type cells and mutant cells to incorporate exogenous nucleoside to the corresponding nucleoside triphosphate indicated that the KAB1 and KAB5 mutant cells were refractory to normal inhibition by NBMPR. Moreover, rapid transport studies indicated that mutant cells, unlike wild type parental cells, had acquired a substantial NBMPR-insensitive nucleoside transport component. Binding studies with [3H]NBMPR indicated that KAB5 cells were 70-75% deficient in the number of NBMPR binding sites, whereas KAB1 cells possessed a wild type complement of NBMPR binding sites. These data suggest that the NBMPR binding site in wild type S49 cells is genetically distinguishable from the nucleoside carrier site.     

Development of 1-cell embryos from different strains of mice in CZB medium

One-cell embryos from several different strains of mice have been cultured to the blastocyst stage in CZB medium. CZB medium can be used to culture CF1 x B6SJLF1/J 1-cell embryos to the blastocyst stage provided glucose is introduced into the medium on Day 3 of culture. The amount of glucose required for embryo development was titrated using a concentration range of 5.5 to 49.5 mM. With the exception of the highest concentration, all glucose levels tested supported 65-85% development to the morula and blastocyst stages. Variations of CZB medium were tested for their ability to support the development of 1-cell embryos from 4 strains of mice. For embryos from CF1 and DBA/2J (both x B6SJLF1/J) mice, which exhibit a "2-cell block" to development in vitro, CZB medium containing glutamine with the addition of glucose on Day 3 supported optimum development from the 1-cell stage to morula and blastocysts (79% and 87%). For embryos from B6D2F1/J and CD1 female mice (both x B6SJLF1/J males), which do not exhibit a "2-cell block" to in vitro development, optimum development to morula and blastocyst stages (95% and 50%) was in CZB medium containing both glutamine and glucose from the start of culture.     

Diabetic Ketoacidosis in Peruvian Patients with Type 2 Diabetes Mellitus

ObjectiveTo describe the clinical and laboratory characteristics of diabetic ketoacidosis (DKA) in adult Peruvian patients with type 2 diabetes mellitus.MethodsIn this cross-sectional analysis, we reviewed clinical charts of type 2 diabetic patients with DKA admitted to Cayetano Heredia Hospital between 2001 and 2005 for data on demographics, previous treatment, previous hospital admissions for DKA, family history of diabetes, precipitating factors, hospital course, mortality, and insulin use 3 and 6 months after the index DKA episode. Patients older than 18 years who had confirmed DKA were included. Patients with type 1 diabetes mellitus were excluded.ResultsWe report on 53 patients with DKA for whom complete clinical and laboratory data were available. Of the 53 patients, 39 (74%) were men; mean age (± SD) was 45 ± 12 years; and 22 (42%) had no previous diagnosis of type 2 diabetes. The following mean (± SD) laboratory values were obtained at DKA diagnosis: glucose, 457 ± 170 mg/dL; pH, 7.15 ± 0.14; bicarbonate, 7.73 ± 6 mEq/L; and anion gap, 24.45 ± 7.44 mEq/L. Of the 53 DKA episodes, 35 (66%) were severe (arterial pH < 7.0 and/or serum bicarbonate < 10 mEq/L). The following precipitating factors were discerned: discontinuation of treatment in 21 (40%), infections in 16 (30%), intercurrent illness in 3 (6%), and no identifiable cause in 13 (25%). Mortality rate was 0%. Three and 6 months after the index DKA episode, insulin was used by 65% and 56% of patients, respectively.ConclusionIn countries with a low incidence of type 1 diabetes, DKA is frequently reported in patients with type 2 diabetes. In this study, 42% of patients had new-onset disease. Most DKA episodes were severe and were related to infection or noncompliance with treatment. (Endocr Pract. 2008;14:442-446)     

适合飞虱虫疠霉菌丝生产的液体培养基组分及发酵条件

蚜虫、飞虱、叶蝉等是威胁农业生产的刺吸式口器害虫,长期以来依赖化学农药防治,严重影响农产品的安全性和农业生态环境.探讨这类害虫的生物防治途径,减轻农产品化学农药的残留污染,一直受到国内外学者的关注.虫霉(En-tomophthorales)的许多种类具有优异的诱病杀虫能力,尤其通过主动弹射孢子而在害虫种群中高强度流行的特征,可在短期内迅速压低虫口密度,是极其重要的杀虫微生物资源[1～3].     

Development of food grade media for the preparation of Lactobacillus plantarum starter culture

Based on MRS medium, two types of food grade (FG) culture media (FG medium I and FG medium II) for the preparation of a concentrated starter culture of Lactobacillus plantarum NRIC 0380 to manufacture a new type of instant Chinese noodle, the fermented instant Chinese noodle, were developed using FG materials. FG medium I, which is for normal static culture, contains table sugar (sucrose), Yeast peptone standard type F, Sunsoft Q-17S (emulsifier), sodium acetate, trisodium citrate and MnSO(4).4-5H(2)O. FG medium II was designed to be used for the pH-controlled jar fermentor culture conditions. Therefore, sodium acetate and trisodium citrate as a buffer to prevent acidification of medium were omitted from FG medium I. When L. plantarum NRIC 0380 was cultured under the pH-controlled jar fermentor culture conditions, the kinetics of growth, sugar consumption and lactic acid production in FG medium II were quite similar to those observed in the Difco Lactobacilli MRS Broth. Furthermore, growths of many lactobacilli strains isolated from various fermented foods in FG medium I were also quite similar to those observed in MRS medium. Therefore, simple and practical FG media for the culture of lactobacilli were successfully established.     

Comparison of fructooligosaccharide utilization by Lactobacillus and Bacteroides species

The utilization of 1-kestose (GF(2)) and nystose (GF(3)), the main components of fructooligosaccharides (FOS), by Lactobacillus and Bacteroides species was examined. Of seven Lactobacillus and five Bacteroides strains that utilized FOS, L. salivarius, L. rhamnosus, L. casei, and L. gasseri utilized only GF(2), whereas L. acidophilus and all the Bacteroides strains utilized both GF(2) and GF(3). Only the strains able to utilize both GF(2) and GF(3) had β-fructosidase activity in the culture supernatants. The culture supernatants of the Lactobacillus strains had higher β-fructosidase activity for GF(2) than for GF(3), whereas those of the Bacteroides strains had higher activity for GF(3) than for GF(2). Furthermore, β-fructosidase activity of the culture supernatants of the Lactobacillus cells grown in the GF(3) medium was much higher than that of the cells grown in the GF(2) medium, whereas the activity of the culture supernatants of the Bacteroides cells grown in the GF(3) medium was almost the same as that of the cells grown in the GF(2) medium. These results indicate that Lactobacillus species metabolize FOS in a different way from that of Bacteroides species.     

Production of long-chain polyunsaturated fatty acids by monoxenic growth of labyrinthulids on oil-dispersed agar medium

A novel method is proposed for the production of long-chain polyunsaturated fatty acids (LCPUFA) by labyrinthulids. The method comprises a monoxenic culture with Psychlobacter phenylpyruvicus, using agar medium in which oil was dispersed. Soybean oil (SBO) was selected as the optimum material for an oil-dispersed agar medium. The labyrinthulids showed three-dimensional growth and an anastomosing ectoplasmic network in the SBO-dispersed agar medium. The oil plate changed from an opaque culture to a more transparent culture, due to growth of the labyrinthulids. The optimum culture conditions were 25-30 degrees C, an initial pH of 6-10 and artificial seawater with a salt concentration of 50-100%. These conditions are close to those where these strains were isolated. The maximum LCPUFA production (0.59 g/l) and dry cell weight (4.93 g/l) was obtained using strain S3-2 (isolated from Ishigaki Island) with 1.5% SBO at 14 days. This value was about 30 times more than that using glucose instead of SBO. The method proposed is promising in terms of the production of LCPUFA from reproducible oils.