Biosynthesis of biotin-vitamers from unsaturated higher fatty acids by bacteria

The biosynthesis of biotin-vitamers from unsaturated higher fatty acids by the resting cell system of bacteria was investigated. Biotin-vitamer formation from oleic, linoleic and linolenic acids was found in certain bacteria belonging to the genera Enterobacter, Agrobacterium, Bacillus, Escherichia and Micrococcus. The biotin-vitamers were identified as a mixture of 7,8-diaminopelargonic acid, desthiobiotin and biotin. Metabolites other than biotin-vitamers from those fatty acids were analyzed by gas-liquid chromatography and mass spectrometry. Linoleic, oleic, C-17 and C-15 saturated fatty acids were identified as the main metabolites of linolenic acid. The pathway of biosynthesis of pimelic acid from linolenic acid by a strain of Bacillus sphaericus AKU 0227 was also studied.     

Microbiological activity of biotin-vitamers

The growth requirement or growth-promoting effect of biotin-vitamers on bacteria and yeasts was investigated. Biotin, dethiobiotin and biocytin (N-e-biotinyl-L-lysine) were shown to be required for growth in a number of bacteria and yeasts. The biological activity of dethiobiotin was relatively higher than that of biotin, but was negative for lactic acid bacteria. Biocytin had high activity for Bacillus subtilis (natto), Debaryomyces japonicus and Hansenula capsulata. The biotin activity of 7-keto-8-aminopelargonic and 7,8-diaminopelargonic acids was low or negligible for bacteria but relatively high for yeasts such as the genera of Endomyces, Endomycopsis and Saccharomyces. Pimelic, pelargonic and pelargonylhydroxamic acids had no growth requirement for or growth-promoting effect on any of the bacteria or yeasts tested.     

Formation of a biotin precursor, pimelic acid, in yeasts from C18 fatty acids

The biosynthesis of biotin-vitamers from C18 fatty acids in the resting cell reaction system of yeasts was investigated. The formation of pimelic acid (a biotin precursor) and biotin-vitamers (a mixture of 7-keto-8-aminopelargonic acid and dethiobiotin) from linolenic, linoleic, and oleic acids was observed in certain yeasts belonging to the genera Cryptococcus, Candida, Rhodotorula, and Trichosporon. Metabolites from linolenic acid were analyzed by gas-liquid chromatography and mass spectrometry. Linoleic, oleic, stearic, heptadecanoic, palmitic, pentadecanoic, and pimelic acids were identified as metabolites of linolenic acid. The existence of a route to pimelic acid from linolenic acid in a strain of Rhodotorula rubra AKU 4836 was also indicated.     

Effects of the yeast extract components pyrroloquinoline quinone and aspartic acid on vitamin B12 production in Klebsiella pneumoniae IFO 13541

The production of vitamin B12 from carbohydrates, peptone, casamino acid, etc., by intestinal bacteria was investigated. Klebsiella pneumoniae IFO 13541 was the most efficient strain for vitamin B12 production, which depended exclusively on the concentration of yeast extract added to the medium. A concentrated solution of yeast extract (1 ml) was chromatographed on a Sephadex G-25 column (1 x 180 cm) and eluted with H2O (eighty fractions of 3 ml each were collected). It was found that fractions in which bacterial growth was most prevalent also exhibited the highest amount of vitamin production. The effectiveness of yeast extract was shown by the participation of pyrroloquinoline quinone and aspartic acid in the growth stimulation and in the vitamin B12 production in this strain.     

Biotin supply by large bowel bacteria in minipigs: evidence from intracaecal avidin

The influence of a change of colonic availability of biotin on biotin status was studied. This was done by inhibition of biotin absorption by intracaecal avidin infusion. Five adult minipigs with a permanent caecal 'T' cannula were fed on a semi-synthetic, biotin-deficient diet for 4 months. Following an 8-week adaptation period there were nine sequential 1-week infusion periods with or without oral lactulose or antibiotics. Avidin infusion during weeks 2, 5 and 8 amounted to 18 mg/d (13 U/mg). Plasma biotin concentrations were not changed by avidin infusions. There was a significant average 84% rise in faecal biotin excretion during the avidin periods. Urinary biotin output following avidin decreased by 21%. This is taken as evidence that biotin synthesized by colonic bacteria is available for host metabolism. A rough estimate shows that under basal conditions 1.7-17% of the metabolic allowance may be covered by this metabolic route.     

Biotin analysis of commercial vitamin and other nutritional supplements

Because previous observations suggest that biotin may be present in vitamin preparations not labeled as containing biotin, we determined the biotin content of several over-the-counter vitamin and nutritional supplements said to contain biotin (group 1) and several in which biotin content was not specified (group 2). Biotin concentration was measured using the 125I-avidin assay which detects total avidin-binding substances. Water extracts were assayed for free biotin and acid hydrolysates were assayed for total biotin. The results of the 125I-avidin assay agreed with the stated biotin content for most vitamin and nutritional supplements in group 1. Biotin was the only avidin-binding substance in the preparations from group 1, based on reversed-phase chromatography. However, some vitamin and nutritional supplements in group 2 contained nutritionally significant amounts of biotin, particularly if the supplement contained liver or yeast extract. Total biotin was significantly higher than free biotin in one supplement; the difference was attributable to release of biotin rather than a biotin analog. We conclude that biotin may be present in some vitamin and nutritional supplements not labeled as containing biotin; biotin intake might be under-estimated if the subject is receiving a nutritional supplement containing extracts of liver or yeast.     

不同碳源对固定化反硝化菌脱氮的影响

为寻找较为经济、高效的有机碳源 ,分别外加葡萄糖、蔗糖、甲醇和乙酸 ,以研究它们对固定化反硝化菌脱氮的影响。结果表明 ,固定化反硝化菌能有效利用上述碳源 ,进行反硝化作用。其中采用葡萄糖、蔗糖和乙酸的反硝化速率较快。HRT为 6h时 ,脱氮率达 96%以上。若碳源较丰富 ,反硝化过程中的氨化作用并不明显 ,被转化成氨氮的硝态氮低于被还原总量的 5 %。采用固定化反硝化菌处理COD NO-3-N较低 ,且不外加碳源 ,起始浓度分别为 45 2和 2 4 6mg L的实际水样 ,分别经过 60h和 3 2h后 ,脱氮率达 90 %以上。固定化细菌能利用水中部分的有机物进行反硝化作用     

Biotin in human milk: methods, location, and chemical form.

For infants, no Recommended Dietary Allowance for biotin has been published; the estimated safe and adequate intake seems to be based on measurements of human milk. However, published estimates of the biotin content disagree substantially. We sought to address several of the potential sources of disagreement by defining the conditions for the collection, storage, and subcompartment distribution of biotin in human milk using the [125I]avidin assay. Composition of the collection vessel (glass vs. common plastics) had no effect on biotin content of human milk. The biotin content of milk did not change during storage at room temperature for at least 1 wk, at 5 degrees C for at least 1 mo, or at -20 degrees C or -70 degrees C for at least 1.5 y. Biotin in the cell pellet and fat fraction accounted for less than 5% of that in the skim fraction. Of the biotin in the skim fraction, none (less than 3%) was reversibly bound to macromolecules, and less than 5% was covalently bound to macromolecules. We conclude that assay of free biotin will detect almost all of the biotin present in a sample of mature human milk.     

Probiotics production and alternative encapsulation methodologies to improve their viabilities under adverse environmental conditions

Probiotic products are dietary supplements containing live microorganisms producing beneficial health effects on the host by improving intestinal balance and nutrient absorption. Among probiotic microorganisms, those classified as lactic acid bacteria are of major importance to the food and feed industries. Probiotic cells can be produced using alternative carbon and nitrogen sources, such as agroindustrial residues, at the same time contributing to reduce process costs. On the other hand, the survival of probiotic cells in formulated food products, as well as in the host gut, is an essential nutritional aspect concerning health benefits. Therefore, several cell microencapsulation techniques have been investigated as a way to improve cell viability and survival under adverse environmental conditions, such as the gastrointestinal milieu of hosts. In this review, different aspects of probiotic cells and technologies of their related products are discussed, including formulation of culture media, and aspects of cell microencapsulation techniques required to improve their survival in the host.     

直肠菌群对两种植物胶的体外发酵特性研究

目的探讨植物胶被肠道菌群发酵利用的规律。方法本研究分别以瓜尔豆胶和果胶为唯一碳源,对直肠菌群进行体外发酵,分别在不同时间取样,测pH、运用选择性平板计数、气相色谱测短链脂肪酸含量。结果两种培养基在肠道菌群发酵过程中,发酵液的pH值呈逐渐下降趋势;除乳杆菌属外,其它各类菌在两种碳源的培养条件下均有较明显的下降,尤其是拟杆菌的数量在发酵中后期急剧减少,但总厌氧菌数较稳定。两种碳源均能被肠道菌群利用产生短链脂肪酸,其中瓜尔豆胶产异丁酸量最大,其次为丙酸,丁酸的产量最少,乳酸在发酵过程中短暂积累后被迅速利用而消耗;果胶产丙酸的量最大,乙酸次之,丁酸的产量最少,乳酸虽然也有一个短暂蓄积,但量非常少而且8h后检测不到乳酸。结论食物中所含植物胶能被肠道菌群利用,并且在发酵过程中肯定有不同菌属的生长演替,但两种植物胶都不利于拟杆菌属的生长。     

小分子肽产生菌培养基碳源与氮源的优化

目的:探讨不同碳源、氮源对乳酸杆菌小分子肽产量及抑菌效果的影响。方法:用1%的不同碳源和2%的不同氮源替换基础培养基中的葡萄糖、酵母膏和蛋白胨,同时改变基础培养基中的葡萄糖浓度,分别在相同条件下发酵,双层平板法检测抑菌效果,同时测定发酵液的OD值和PH值。结果:不同碳源均能促进LB-9菌株的生物量增加,生物量从高到低依次为葡萄糖、果糖、蔗糖、乳糖、木糖、糊精、玉米浆、可溶性淀粉,其中葡萄糖为碳源的发酵液的生物量最大。各有机氮源均可促进小分子肽的产生,而无机氮源不能。有机氮源发酵液的抑菌效果从高到低依次为酵母膏、牛肉膏、多胨、鱼蛋白胨、胰蛋白胨、大豆胨。结论:葡萄糖是本实验最好的碳源。葡萄糖为碳源的发酵液的生物量最大,小分子肽产量随葡萄糖浓度的增加而增加。菌体细胞生长最好的氮源是酵母膏,有机氮源均可促进小分子肽的产生,而无机氮源不能。     

Folic acid utilization from high fiber diets in rats

This study was designed to examine the effect of several sources of dietary fiber on the utilization of folic acid added to the diets of rats. Weanling rats were given a low folacin basal diet for 21 days, divided into various groups and then fed folic acid (pteroylglutamic acid) and/or fiber-supplemented diets for 7 or 8 days. The slope of the liver folacin response was measured as an indicator for utilization of added folic acid. Fecal folacin excretion was measured as an indicator of unabsorbed dietary folacin plus folacin synthesis by intestinal bacteria. There was no detectable effect of cellulose, xylan, pectin or wheat bran on the utilization of added folic acid. Liver and fecal folacin content indicated that some fiber sources contributed additional available folacin to the animals from intestinal synthesis or naturally occurring folacin. Cellulose acted as a simple dietary dilutant and had no significant effect on the utilization of added folic acid or total fecal folacin excretion. Xylan stimulated intestinal folacin synthesis, and this was reflected in higher fecal and liver folacin content. Wheat bran and beans (two varieties of each) contained measurable folacin or stimulated synthesis of bacterial folacin, which appeared to be available to the rat.     

云南边防部队腹泻患者中8株豚鼠气单胞菌的分离鉴定及致病性研究

目的:对豚鼠气单胞菌分离株进行鉴定,掌握豚鼠气单胞菌在驻云南边防部队引起腹泻的情况。方法:碱性蛋白胨水增菌,TCBS、庆大霉素或碱性琼脂平板分离培养,进行系统生化鉴定,电子显微镜观察形态。小白鼠腹腔注射法测定其毒力,开展致病性研究。药敏试验采用纸片扩散法。结果:从502份腹泻患者粪便标本中检出8株豚鼠气单胞菌。结论:分离的8株豚鼠气单胞菌具有较强毒力,与致病性密切相关。药敏试验可作为此菌感染时临床用药的重要参考。     

Differences in carbon source utilization of Salmonella Oranienburg and Saintpaul isolated from river water

Long-term exposure to river water by non-indigenous micro-organisms such as Salmonella may affect metabolic adaptation to carbon sources. This study was conducted to determine differences in carbon source utilization of Salmonella Oranienburg and Salmonella Saintpaul (isolated from tropical river water) as well as the control strain Salmonella Typhimurium exposed to laboratory, river water, and host cells (Hep-2 cell line) growth conditions. Results showed that Salmonella Oranienburg and Salmonella Saintpaul showed better ability for carbon source utilization under the three growth conditions evaluated; however, S. Oranienburg showed the fastest and highest utilization on different carbon sources, including D-Glucosaminic acid, N-acetyl-D-Glucosamine, Glucose-1-phosphate, and D-Galactonic acid, while Salmonella Saintpaul and S. Typhimurium showed a limited utilization of carbon sources. In conclusion, this study suggests that environmental Salmonella strains show better survival and preconditioning abilities to external environments than the control strain based on their plasticity on diverse carbon sources use.     

DNA探针在呼吸机相关性肺炎病原学检测中的诊断价值

目的建立一种早期、快速检测呼吸机相关性肺炎致病菌的分子生物学方法。方法采用聚合酶链反应合成铜绿假单胞菌、甲氧西林耐药金黄色葡萄球菌、大肠杆菌、肺炎克雷伯杆菌和流感嗜血杆菌这5种细菌的特异DNA探针和细菌16SrRNA的通用探针,分别与生物素标记的细菌、病毒和真菌DNA杂交。杂交法和培养法同时检测100份痰液标本。结果所合成的DNA探针具有高度特异性,与其他细菌、病毒、真菌间无交叉反应。该方法可检测出1 ng细菌DNA。杂交法阳性率显著高于培养法。结论所合成的DNA探针敏感性高,特异性强,具有较高的应用价值,可应用于临床标本检测。     

E.ColiO_(157):H_7的“VT”测定及致病性实验感染的研究

采用改良无铁酪蛋白水解物——酵母浸膏液作为产毒培养基,以多粘菌素 B(0.1mg/ml)处理菌体,再提取细菌滤液进行 vero 细胞毒素的测定;结果13株 E.ColiO_(157):H_7均能产生使 vero 细胞溶解、变性和死亡的 vero—toxin(VT)。运用实验小鼠,于腹部皮下注射1.2×10~8CFU/ml 活菌(0.3ml/只),于4～6h,小鼠即开始发病,其出现的症状及发病后各脏器的组织学改变,酷似人体发病后的表现,基本再现了出血性结肠炎和溶血性尿毒症综合征的疾病特征。     

Determination of the biotin content of select foods using accurate and sensitive HPLC/avidin binding

Assessing dietary biotin content, biotin bioavailability, and resulting biotin status are crucial in determining whether biotin deficiency is teratogenic in humans. Accuracy in estimating dietary biotin is limited both by data gaps in food composition tables and by inaccuracies in published data. The present study applied sensitive and specific analytical techniques to determine values for biotin content in a select group of foods. Total biotin content of 87 foods was determined using acid hydrolysis and the HPLC/avidin-binding assay. These values are consistent with published values in that meat, fish, poultry, egg, dairy, and some vegetables are relatively rich sources of biotin. However, these biotin values disagreed substantially with published values for many foods. Assay values varied between 247 times greater than published values for a given food to as much as 36% less than the published biotin value. Among 51 foods assayed for which published values were available, only seven agreed within analytical variability (±20%). We conclude that published values for biotin content of foods are likely to be inaccurate.     

Effects of defaunation on fermentation characteristics and biotin balance in an artificial rumen-simulation system (RUSITEC) receiving diets with different amounts and types of cereal

Biotin is required by rumen microbes for efficient fermentation. To evaluate the role of protozoa in ruminal biotin metabolism, five diets composed of grass hay or of grass hay/cereal grain mixtures were supplied to faunated or defaunated RUSITEC fermenters. In the mixed diets, hay was replaced to 33:67 or 67:33 w/w on an air-dried basis by either wheat or maize grain in order to simulate different cellulolytic and amylolytic fermentation conditions. Defaunation increased SCFA production, whereas NH4 concentration and the release of CH4 were reduced. Biotin input declined when cereal grain was used to replace the hay. With the exception of the high-wheat treatment, defaunated fermenters yielded higher biotin outputs than faunated fermenters. The biotin balance, calculated as the difference between the total biotin output (biotin in the solid residue contained in the nylon bags after fermentation plus the biotin in the effluent) and the biotin input with the feed, was negative for all the dietary treatments apart from fermenters supplied with the high-maize diet. It was less negative or, in the case of the high-maize diets, more positive for defaunated compared with faunated fermenters. It was concluded that, under normal faunated conditions, protozoa directly utilise or indirectly affect the bacterial synthesis and/or utilisation of biotin. With diets of a high fermentation potential, as realised with the high-wheat diet, protozoa prevent the development of a bacterial population that would utilise high or synthesise low amounts of biotin.     

毒鼠强及其医疗废弃物的安全处理方法

目的 探讨毒鼠强及其医疗废弃物的安全处理方法。方法 为考察毒鼠强在酸、碱及高温条件下的化学稳定性,分别将毒鼠强置于氢氧化钠、盐酸、硫酸和硝酸中,在不同酸碱浓度、温度和时间条件下进行处理,处理结束后用气相色谱法测定毒鼠强的残留量,评价毒鼠强的消解率;将毒鼠强置于密封的安瓿瓶中,在不同温度、不同时间条件下进行烘烤,处理结束后测定毒鼠强的残留量,评价毒鼠强的消解效率。为考察活性炭对水和血中毒鼠强的吸附效率,分别将活性炭置于含毒鼠强的水及血中,室温下静置24h后测定水及血中的毒鼠强残留量,评价活性炭对血及水中毒鼠强的吸附效率。结果 毒鼠强在100℃、6．0mol／L盐酸中处理0．5h即完全消解,在3．0mol／L盐酸及6．0mol／L氢氧化钠中则需3h;在浓硫酸和浓硝酸中室温放置24h亦可完全消解。毒鼠强在300℃高温下处理4．5h可以完全消解。活性炭能有效地吸附水或血中的毒鼠强,平均吸附率在90％以上。结论 对毒鼠强原料药或杀鼠剂成品宜采用酸、碱湿法消解;对受毒鼠强污染的固体废弃物宜采用高温消解;对医疗废弃液,先用活性炭吸附其中的毒鼠强后,再进行高温消解。     

Biotin absorption by distal rat intestine

We used the in vivo intestinal loop approach, with short (10-min) and long (3-h) incubations, to examine biotin absorption in proximal jejunum, distal ileum, cecum and proximal colon. In short-term studies, luminal biotin disappearance from rat ileum was about half that observed in the jejunum, whereas absorption by proximal colon was about 12% of that in the jejunum. In 3-h closed-loop studies, the absorption of 1.0 microM biotin varied regionally. Biotin absorption was nearly complete in the small intestine after 3 h; however, only about 15% of the dose had been absorbed in the cecum and 27% in the proximal colon after 3 h. Independent of site of administration, the major fraction of absorbed biotin was recovered in the liver; measurable amounts of radioactive biotin were also present in kidney and plasma. The results support the potential nutritional significance for the rat of biotin synthesized by bacteria in the distal intestine, by demonstrating directly an absorptive capability of mammalian large bowel for this vitamin.