Biotin Requirement Research Articles

A bacterial methyltransferase that initiates biotin synthesis, an attractive anti-ESKAPE druggable pathway.

The covalently attached cofactor biotin plays pivotal roles in central metabolism. The top-priority ESKAPE-type pathogens, Acinetobacter baumannii and Klebsiella pneumoniae, constitute a public health challenge of global concern. Despite the fact that the late step of biotin synthesis is a validated anti-ESKAPE drug target, the primary stage remains fragmentarily understood. We report the functional definition of two BioC isoenzymes (AbBioC for A. baumannii and KpBioC for K. pneumoniae) that act as malonyl-ACP methyltransferase and initiate biotin synthesis. The physiological requirement of biotin is diverse within ESKAPE pathogens. CRISPR-Cas9-based inactivation of bioC rendered A. baumannii and K. pneumoniae biotin auxotrophic. The availability of soluble AbBioC enabled the in vitro reconstitution of DTB/biotin synthesis. We solved two crystal structures of AbBioC bound to SAM cofactor (2.54 angstroms) and sinefungin (SIN) inhibitor (1.72 angstroms). Structural and functional study provided molecular basis for SIN inhibition of BioC. We demonstrated that BioC methyltransferase plays dual roles in K. pneumoniae infection and A. baumannii colistin resistance.

Biotin: a scoping review for Nordic Nutrition Recommendations 2023.

Biotin is a water-soluble B-vitamin with key roles in metabolism and are found in most foods at low concentrations. Symptomatic biotin deficiency is rare, and few studies have investigated biotin requirements in relation to health outcomes. Data to support the setting of dietary reference values for biotin are limited.

Metabolic adaptation to vitamin auxotrophy by leaf-associated bacteria

Auxotrophs are unable to synthesize all the metabolites essential for their metabolism and rely on others to provide them. They have been intensively studied in laboratory-generated and -evolved mutants, but emergent adaptation mechanisms to auxotrophy have not been systematically addressed. Here, we investigated auxotrophies in bacteria isolated from Arabidopsis thaliana leaves and found that up to half of the strains have auxotrophic requirements for biotin, niacin, pantothenate and/or thiamine. We then explored the genetic basis of auxotrophy as well as traits that co-occurred with vitamin auxotrophy. We found that auxotrophic strains generally stored coenzymes with the capacity to grow exponentially for 1–3 doublings without vitamin supplementation; however, the highest observed storage was for biotin, which allowed for 9 doublings in one strain. In co-culture experiments, we demonstrated vitamin supply to auxotrophs, and found that auxotrophic strains maintained higher species richness than prototrophs upon external supplementation with vitamins. Extension of a consumer-resource model predicted that auxotrophs can utilize carbon compounds provided by other organisms, suggesting that auxotrophic strains benefit from metabolic by-products beyond vitamins.

The negative impacts of dietary biotin deficiency on antioxidant status, apoptosis and tight junction protein transcription of immune organs in grass carp (Ctenopharyngodon idella)

Low-molecular-weight vitamin biotin is an essential nutrient substance for all animal normal growth. Previous exploration has documented that dietary biotin deficiency led to fish growth retardation and a decrease in immunity, whereas its detrimental impacts on fish other physiological status were still not revealed yet. Herein, further exploration was performed to excavate the latent influence of dietary biotin deficiency on antioxidant status, apoptosis and tight junction protein of immune organs (the skin, spleen and head kidney). In this research, grass carp (Ctenopharyngodon idella) (117.11 ± 0.48 g) as a model were fed six graded levels of biotin diets (0.012, 0.110, 0.214, 0.311, 0.427 and 0.518 mg/kg diet) in triplicate for 70 days, followed by a challenge with A. hydrophila for 6 days. Our data from above three immune organs manifested that biotin deficiency (0.012 mg/kg diet): (1) markedly increased oxidative damage degree as evidenced by the obtained highest value in all oxidative damage indicators and exhibited the lowest significant value in almost all antioxidant enzymes activities and corresponding gene expressions, where this action may be in part correlated with the modulation of Nrf2 signaling (P < 0.05); (2) signally aggravated cell apoptosis by altering the expression profiles of mitochondria and death receptor pathways involved genes (such as caspase-3,8 and FasL), where this mechanism may be partly connected with p38MAPK signaling (P < 0.05); (3) dramatically damaged tight junctions by regulating the expression profiles of a series of complexes (such as occludin and claudins), where the reason may be in part correlated with myosin light chain kinase (MLCK) signaling (P < 0.05). Differently, the transcriptional levels of MnSOD, GPx4, JNK and ZO-2 (only in spleen) were not regulated by dietary biotin in above three immune organs (P > 0.05). Furthermore, a broken line analysis showed that dietary biotin requirement levels for on-growing grass carp is 0.245–0.354 mg/kg diet for parameters (ROS content, caspase3 and claudin-3c expression levels).

Biotin biosynthesis affected by the NADPH oxidase and lipid metabolism is required for growth, sporulation and infectivity in the citrus fungal pathogen Alternaria alternata

The tangerine pathotype of Alternaria alternata affects many citrus cultivars, resulting in yield losses. The capability to produce the host-selective toxin and cell-wall-degrading enzymes and to mitigate toxic reactive oxygen species is crucial for A. alternata pathogenesis to citrus. Little is known about nutrient availability within citrus tissues to the fungal pathogen. In the present study, we assess the infectivity of a biotin deficiency mutant (ΔbioB) and a complementation strain (CP36) on citrus leaves to determine how biotin impacts A. alternata pathogenesis. Growth and sporulation of ΔbioB are highly dependent on biotin. ΔbioB retains its ability to acquire and transport biotin from the surrounding environment. Growth deficiency of ΔbioB can also be partially restored by the presence of oleic acid or Tween 20, suggesting the requirement of biotin in lipid metabolism. Experimental evidence indicates that de novo biotin biosynthesis is regulated by the NADPH oxidase, implicating in the production of H2O2, and is affected by the function of peroxisomes. Three genes involved in the biosynthesis of biotin are clustered and co-regulated by biotin indicating a transcriptional feedback loop activation. Infectivity assays using fungal mycelium reveal that ΔbioB cultured on medium without biotin fails to infect citrus leaves; co-inoculation with biotin fully restores infectivity. The CP36 strain re-expressing a functional copy of bioB displays wild-type growth, sporulation and virulence. Taken together, we conclude that the attainability or accessibility of biotin is extremely restricted in citrus cells. A. alternata must be able to synthesize biotin in order to utilize nutrients for growth, colonization and development within the host.

Isolation and identification of Azospirillum and Azotobacter species from Acacia spp. at Riyadh, Saudi Arabia

Populations of Azospirillum and Azotobacter isolated and identified from the soil rhizosphere of Acacia ehernbergiana, A. gerrardii and A. tortilis from three sites varied widely irrespective of tree species, size and site. Azospirillum strains were purified and characterized through morphological, microscopic and biochemical tests for motility, cell shape, pigmentation, colony color, gram reaction, optimal temperatures, biotin requirement, pH growth, acidification of peptone glucose medium, ability of nitrogen fixation, growth on 3% NaCl, and D-glucose and D-ribose utilization. Twenty Azospirillum isolates were divided into four matching characters. They were identified as A. lipoferum, A. brasilense, A. dobereinerae and A. zeae. The same above tests with omission of temperatures, biotin requirement, and acidification of peptone and addition of starch hydrolysis, H2S, urease, oxidase and sucrose, maltose and mannitol as carbon source were applied to Azotobacter strains. Azotobacter isolates were divided into three matching characters. They were identified as A. chroococcum, A. beijerinckii and A. salinestris.

Dietary biotin requirement of fingerling Channa punctatus (Bloch)

ABSTRACTDietary biotin requirement of fingerling Channa punctatus (4.52 ± 0.46 g) was estimated by conducting a 16-week growth trial. Fish were fed casein gelatin-based purified diets (450 g/kg crude protein, 18.39 kJ/g gross energy) with seven levels of dietary biotin (0, 0.04, 0.09, 0.47, 1.02, 1.43, and 1.96 mg/kg diet) to triplicate groups near to satiation. Significantly higher absolute weight gain (P = 0.0018), specific growth rate (P = 0.0027), protein gain (P = 0.0016), protein deposition (P = 0.0038), and lower feed conversion ratio (P = 0.0003) were shown in fish fed diet containing 0.47 mg/kg biotin, whereas liver biotin concentration showed a significant improvement (P = 0.0021) with increasing levels of dietary biotin up to 1.02 mg/kg. Broken-line analysis of absolute weight gain, protein gain, and liver biotin concentrations indicated that fingerling C. punctatus require biotin at 0.46, 0.44, and 0.97 mg/kg diet. Based on protein gain, optimum pyridoxine requirement for fingerling C. punctatus is recommended at 0.44 mg/kg diet.

Dietary Biotin Requirement of Fingerling Catla catla (Hamilton) Based on Growth, Feed Conversion Efficiency, and Liver Biotin Concentration

AbstractA 12‐wk experiment was conducted to determine the dietary biotin requirement of the fingerling Catla catla (7.9 ± 0.37 cm; 3.5 ± 0.12 g). Eight diets (35% crude protein, 16.72 kJ/g gross energy) with different levels of biotin (0, 0.05, 0.1, 0.5, 1.0, 1.5, 2.0, and 2.5 mg/kg diet) were fed to triplicate groups of fish to apparent satiation. Highest percent weight gain, protein retention efficiency, and best feed conversion ratio were observed in fish fed 0.5 mg biotin per kg diet. However, fish fed diets containing dietary biotin of 1.0, 1.5, 2.0, and 2.5 mg/kg did not show significant (P &gt; 0.05) differences compared to those fed on dietary biotin of 0.5 mg/kg. Hematological indices, including hematocrit value, hemoglobin content, and red blood cell counts were found to be directly proportional (P &lt; 0.05) to the dietary biotin levels up to 0.5 mg/kg, beyond which a plateau was recorded. Pyruvate carboxylase activity (PCA) was also found to increase with the incremental levels of dietary biotin up to 0.5 mg/kg and further increasing dietary biotin concentration led to stagnation in PCA of fish. Liver biotin concentrations responded positively (P &lt; 0.05) until saturation, which occurred at 1.0 mg/kg diet. Broken‐line analysis of percent weight gain, protein retention efficiency, PCA, and liver biotin concentrations demonstrated that fingerling C. catla require biotin in the range of 0.41–0.87 mg/kg diet.

Biotin-mediated growth and gene expression in Staphylococcus aureus is highly responsive to environmental biotin.

Biotin (Vitamin B7) is a critical enzyme co-factor in metabolic pathways important for bacterial survival. Biotin is obtained either from the environment or by de novo synthesis, with some bacteria capable of both. In certain species, the bifunctional protein BirA plays a key role in biotin homeostasis as it regulates expression of biotin biosynthetic enzymes in response to biotin demand and supply. Here, we compare the effect of biotin on the growth of two bacteria that possess a bifunctional BirA, namely Escherichia coli and Staphylococcus aureus. Unlike E. coli that could fulfill its biotin requirements through de novo synthesis, S. aureus showed improved growth rates in media supplemented with 10nM biotin. S. aureus also accumulated more radiolabeled biotin from the media highlighting its ability to efficiently scavenge exogenous material. These data are consistent with S. aureus colonizing low biotin microhabitats. We also demonstrate that the S. aureus BirA protein is a transcriptional repressor of BioY, a subunit of the biotin transporter, and an operon containing yhfT and yhfS, the products of which have a putative role in fatty acid homeostasis. Increased expression of bioY is proposed to help cue S. aureus for efficient scavenging in low biotin environments.

Laboratory Evolution of a Biotin-Requiring Saccharomyces cerevisiae Strain for Full Biotin Prototrophy and Identification of Causal Mutations.

Biotin prototrophy is a rare, incompletely understood, and industrially relevant characteristic of Saccharomyces cerevisiae strains. The genome of the haploid laboratory strain CEN.PK113-7D contains a full complement of biotin biosynthesis genes, but its growth in biotin-free synthetic medium is extremely slow (specific growth rate [μ] ≈ 0.01 h-1). Four independent evolution experiments in repeated batch cultures and accelerostats yielded strains whose growth rates (μ ≤ 0.36 h-1) in biotin-free and biotin-supplemented media were similar. Whole-genome resequencing of these evolved strains revealed up to 40-fold amplification of BIO1, which encodes pimeloyl-coenzyme A (CoA) synthetase. The additional copies of BIO1 were found on different chromosomes, and its amplification coincided with substantial chromosomal rearrangements. A key role of this gene amplification was confirmed by overexpression of BIO1 in strain CEN.PK113-7D, which enabled growth in biotin-free medium (μ = 0.15 h-1). Mutations in the membrane transporter genes TPO1 and/or PDR12 were found in several of the evolved strains. Deletion of TPO1 and PDR12 in a BIO1-overexpressing strain increased its specific growth rate to 0.25 h-1 The effects of null mutations in these genes, which have not been previously associated with biotin metabolism, were nonadditive. This study demonstrates that S. cerevisiae strains that carry the basic genetic information for biotin synthesis can be evolved for full biotin prototrophy and identifies new targets for engineering biotin prototrophy into laboratory and industrial strains of this yeast.IMPORTANCE Although biotin (vitamin H) plays essential roles in all organisms, not all organisms can synthesize this vitamin. Many strains of baker's yeast, an important microorganism in industrial biotechnology, contain at least some of the genes required for biotin synthesis. However, most of these strains cannot synthesize biotin at all or do so at rates that are insufficient to sustain fast growth and product formation. Consequently, this expensive vitamin is routinely added to baker's yeast cultures. In this study, laboratory evolution in biotin-free growth medium yielded new strains that grew as fast in the absence of biotin as in its presence. By analyzing the DNA sequences of evolved biotin-independent strains, mutations were identified that contributed to this ability. This work demonstrates full biotin independence of an industrially relevant yeast and identifies mutations whose introduction into other yeast strains may reduce or eliminate their biotin requirements.

Pregnancy and Lactation Alter Biomarkers of Biotin Metabolism in Women Consuming a Controlled Diet

Background: Biotin functions as a cofactor for several carboxylase enzymes with key roles in metabolism. At present, the dietary requirement for biotin is unknown and intake recommendations are provided as Adequate Intakes (AIs). The biotin AI for adults and pregnant women is 30 μg/d, whereas 35 μg/d is recommended for lactating women. However, pregnant and lactating women may require more biotin to meet the demands of these reproductive states.Objective: The current study sought to quantify the impact of reproductive state on biotin status response to a known dietary intake of biotin.Methods: To achieve this aim, we measured a panel of biotin biomarkers among pregnant (gestational week 27 at study entry; n = 26), lactating (postnatal week 5 at study entry; n = 28), and control (n = 21) women who participated in a 10- to 12-wk feeding study providing 57 μg of dietary biotin/d as part of a mixed diet.Results:Over the course of the study, pregnant women excreted 69% more (vs. control; P < 0.001) 3-hydroxyisovaleric acid (3-HIA), a metabolite that accumulates during the catabolism of leucine when the activity of biotin-dependent methylcrotonyl–coenzyme A carboxylase is impaired. Interestingly, urinary excretion of 3-hydroxyisovaleryl-carnitine (3-HIA-carnitine), a downstream metabolite of 3-HIA, was 27% lower (P = 0.05) among pregnant (vs. control) women, a finding that may arise from carnitine inadequacy during gestation. No differences (P > 0.05) were detected in plasma biotin, urinary biotin, or urinary bisnorbiotin between pregnant and control women. Lactating women excreted 76% more (vs. control; P = 0.001) of the biotin catabolite bisnorbiotin, indicating that lactation accelerates biotin turnover and loss. Notably, with respect to control women, lactating women excreted 23% less (P = 0.04) urinary 3-HIA and 26% less (P = 0.05) urinary 3-HIA-carnitine, suggesting that lactation reduces leucine catabolism and that these metabolites may not be useful indicators of biotin status during lactation.Conclusions: Overall, these data demonstrate significant alterations in markers of biotin metabolism during pregnancy and lactation and suggest that biotin intakes exceeding current recommendations are needed to meet the demands of these reproductive states. This trial was registered at clinicaltrials.gov as NCT01127022.

Dietary biotin requirement of juvenile blunt snout bream,Megalobrama amblycephala

This study was conducted to determine the optimal dietary biotin requirement of juvenile Megalobrama amblycephala. Quadruple groups of fish (initial average weight 2.01 ± 0.01 g) were fed thrice daily with six isonitrogenous and isoenergetic purified diets containing 0 (basal diet), 0.015, 0.049, 0.158, 0.624 and 2.49 mg kg−1 biotin, respectively, for 8 weeks. Results showed that survival rate, final weight, feed intake, specific growth rate, protein efficiency ratio and nitrogen retention efficiency all increased significantly (P < 0.01) as dietary biotin levels increased from 0 to 0.049 mg kg−1, whereas the opposite was true for feed conversion ratio. Dressout percentage, condition factor, hepatosomatic index, viscera/body ratio all showed no significant difference (P > 0.05) within the biotin range tested. Contrary to moisture content, whole-body protein and lipid contents showed a positive correlation with dietary biotin levels. In addition, liver biotin content increased significantly (P < 0.05) with increasing dietary biotin levels up to 0.624 mg kg−1. Hepatic pyruvate carboxylase (PC) and acetyl-CoA carboxylase (ACC) activities both showed an increasing trend as dietary biotin levels increased. Based on the regression analysis of weight gain, hepatic PC and ACC activities, the optimal dietary biotin requirement of juvenile Megalobrama amblycephala is estimated to be 0.063, 0.071 and 0.075 mg kg−1, respectively.

Plasma and breast milk biotin concentrations decrease in lactating women consuming a dietary biotin intake exceeding current recommendations (827.10)

Biotin is a water‐soluble B vitamin with many key roles in human metabolism. As a cofactor for several carboxylation reactions, biotin is required for gluconeogenesis, fatty acid synthesis, and leucine catabolism. Biotin may also interact with histones to affect genome expression. The dietary requirement for biotin is unknown. Thus, recommendations are provided as Adequate Intakes (AIs). The biotin AI for adults and pregnant women is 30μg/d and for lactating women, 35μg/d. As part of a controlled feeding study, healthy pregnant (n=26, 27wk gestation), lactating (n=28, 5wk postpartum), and control (non‐pregnant, non‐lactating; n=21) women consumed ~60μg dietary biotin/d for 10‐12 weeks. Plasma and breast milk samples were collected and biotin was measured at baseline (wk 0) and study end (wk 10 or 12). Plasma biotin was measured via ELISA kit and breast milk biotin was measured via LCMS. Throughout the study, the response of plasma biotin varied by reproductive group (P = 0.05). Among pregnant (P=0.65) and control (P=0.88) women, plasma biotin did not change from baseline (pregnant: 130ng/L (105, 161); control: 143ng/L (113, 180)) to study end (pregnant: 137ng/L (111, 170); control: 146ng/L (115, 184)). However, among lactating women, plasma biotin decreased (P &lt; 0.01) from baseline (193ng/L (157, 237)) to study end (136ng/L (111, 167)) as did breast milk biotin concentrations (P = 0.02; baseline: 12pM/mL (8.2, 16.5); study end: 7pM/mL (4.8, 9.7)). In addition, plasma and breast milk biotin concentrations were correlated (rho=0.501; P&lt; 0.001). These results indicate that plasma biotin may be a biomarker for breast milk biotin and that lactating women may benefit from a dietary biotin intake that exceeds the study dose of 60μg/d. Data presented as means and 95% confidence intervals.Grant Funding Source: Support:The Hartwell Foundation,The Gerber Foundation,NIH R03 HD065962‐01A1,Shepherd Univ Foundation

Scientific Opinion on Dietary Reference Values for biotin

Following a request from the European Commission, the Panel on Dietetic Products, Nutrition and Allergies (NDA) derived Dietary Reference Values (DRVs) for biotin. Biotin is a water-soluble vitamin which serves as a co-factor for several carboxylases that play critical roles in the synthesis of fatty acids, the catabolism of branched-chain amino acids and gluconeogenesis. Dietary biotin deficiency is rare. Data on biomarkers of biotin intake or status are insufficient to be used in determining the requirement for biotin. Data available on biotin intakes and health consequences are very limited and cannot be used for deriving DRVs for biotin. As there is insufficient evidence available to derive an Average Requirement and a Population Reference Intake, an Adequate Intake (AI) is proposed. The setting of AIs is based on observed biotin intakes with a mixed diet and the apparent absence of signs of deficiency in the EU, suggesting that current intake levels are adequate. The AI for adults is set at 40 µg/day. The AI for adults also applies to pregnant women. For lactating women, an additional 5 µg biotin/day over and above the AI for adults is proposed, to compensate for biotin losses through breast milk. For infants over six months, an AI of 6 µg/day is proposed by extrapolating from the biotin intake of exclusively breastfed infants aged zero to six months, using allometric scaling and reference body weight for each age group, in order to account for the role of biotin in energy metabolism. The AIs for children aged 1–3 and 4–10 years are set at 20 and 25 µg/day, respectively, and for adolescents at 35 µg/day, based on observed intakes in the EU.

Current knowledge on biotin nutrition in fish and research perspectives

AbstractBiotin, a water‐soluble vitamin, is essential for normal growth, development and health of all animals. In terrestrial animal nutrition, biotin has recently spurred scientific interest because of the increasing body of knowledge on biotin involvement in gene expression, cell cycle and reproduction in mammals, and recent advances in molecular biology techniques allowing a more effective estimation of biotin effects in metabolism and physiology. In contrast, this information is scarce in aquatic animal nutrition, as studies have essentially focused on the estimation of minimum biotin requirement for maximum growth and tissue storage as well as for the formulation of least‐cost diet. This scarcity of information is also due to the lack of well‐established indicators of biotin status in aquatic organisms. The present review is a comparative analysis of current knowledge on biotin physiology and nutritional biochemistry in terrestrial and aquatic animal nutrition. Also, general information on biotin sources, bioavailability, deficiency and requirement in mammals and fish is provided in order to plan further studies. In the future, biotin nutrition studies in aquaculture should also include haematological parameters, histopathology of the gills, liver and kidney, gonad development, gamete quality and quantity, fecundity, larvae survival and gene expression. Dietary biotin requirement levels should be estimated at every life history stage of farmed fish. The potential contribution of intestinal microflora to biotin supply in different fish species should be investigated. All this information will allow a better understanding of the essentiality of biotin in fish growth, development, reproduction and health.

Consumption of a low-carbohydrate and high-fat diet (the ketogenic diet) exaggerates biotin deficiency in mice

ObjectiveBiotin is a water-soluble vitamin that acts as a cofactor for several carboxylases. The ketogenic diet, a low-carbohydrate, high-fat diet, is used to treat drug-resistant epilepsy and promote weight loss. In Japan, the infant version of the ketogenic diet is known as the “ketone formula.” However, as the special infant formulas used in Japan, including the ketone formula, do not contain sufficient amounts of biotin, biotin deficiency can develop in infants who consume the ketone formula. Therefore, the aim of this study was to evaluate the effects of the ketogenic diet on biotin status in mice. MethodsMale mice (N = 32) were divided into the following groups: control diet group, biotin-deficient (BD) diet group, ketogenic control diet group, and ketogenic biotin-deficient (KBD) diet group. Eight mice were used in each group. ResultsAt 9 wk, the typical symptoms of biotin deficiency such as hair loss and dermatitis had only developed in the KBD diet group. The total protein expression level of biotin-dependent carboxylases and the total tissue biotin content were significantly decreased in the KBD and BD diet groups. However, these changes were more severe in the KBD diet group. ConclusionThese findings demonstrated that the ketogenic diet increases biotin bioavailability and consumption, and hence, promotes energy production by gluconeogenesis and branched-chain amino acid metabolism, which results in exaggerated biotin deficiency in biotin-deficient mice. Therefore, biotin supplementation is important for mice that consume the ketogenic diet. It is suggested that individuals that consume the ketogenic diet have an increased biotin requirement.

The effects of the dietary biotin on zebrafishDanio rerioreproduction

AbstractAn experiment was conducted to investigate theeffects of dietary biotin on zebrafish Danio rerioreproduction. Biotin and avidin (biotin antagonist)were added to two isonitrogenous and isocaloricpurified diets to provide molar avidin:biotin ratiosof 0:1 (biotin-sufficient diet) and 120:0 (biotin-unsufficient diet). Each diet was fed to a group ofmales mean initial mass 0.262 g) and a group offemales (mean initial mass 0.285 g) for 99 days.Following this feeding period, males fed biotin-sufficient diet exhibited higher gonado-somaticindex, sperm density, sperm motility and spermviability than those fed biotin-unsufficient diet(P < 0.05). In the presence of biotin-sufficientmales, biotin-sufficient females spawned more eggs(222.2 eggs) than biotin-deficient females (18.8eggs) (P < 0.05). The same pattern was observedwith biotin-deficient males (7.6 vs. 1.8 eggs)(P < 0.05). Biotin-sufficient males generated ahigher percentage of fertilized eggs (90% vs. 42%),hatching rate (62% vs. 27%), larvae survival(98% vs. 37%) and larvae length at 7 days postfertilization (4.4 mm vs. 4.2 mm) than biotin-deficient males (P < 0.05) . Biotin status of themale is of high consideration for successful breed-ing in zebrafish, because it significantly impactsthe reproductive performances of the female.Keywords: Biotin, gonado-somatic index, repro-ductive performance, spermIntroductionBiotin, a water-soluble B-complex vitamin, is anessential nutrient for fish (Shaik Mohamed,Ravisankar & Ibrahim 2000; Halver 2002). Biotinhas been recognized to serve as a covalentlybound coenzyme for four carboxylases:acetyl-CoAcarboxylase (isoforms alpha and beta; E.C.6.4.1.2), pyruvate carboxylase (E.C. 6.4.1.1),propionyl-CoA carboxylase (E.C. 6.4.1.3) and3-methylcrotonyl-CoA carboxylase (E.C. 6.4.1.4)(Dakshinamurti 1994, 2005; Maeland, Waagbo,Sandnes & Hjeltnes 1998; Shiau & Chin 1999;Shaik Mohamed 2001; Rodriguez-Melendez Z Li, Zhang, Mai, Ai, Wan, Zhang Z Maeland et al. 1998; Shiau & Chin1999; Shaik Mohamed et al. 2000; Rodriguez-Melendez & Zempleni 2003; Li et al. 2010).In mammals, it has been found that biotindeficiency negatively impacts spermatogenesis(Dakshinamurti 2005; Cammalleri, Bentivegna M Delost & Terroine 1956). Delayed spermato-genesis and decreased number of spermatozoa inrats were also attributed to biotin deficiency (Terro-ine 1961; Dakshinamurti 2005). More recently,biotin deficiency was found to decrease the fertilityof fruit flies Drosophila melanogaster (Landenberger,Kabil, Harshman & Zempleni 2004).However, despite the extensive studies con-ducted on biotin requirements for maximum

Identification and assessment of markers of biotin status in healthy adults

Human biotin requirements are unknown and the identification of reliable markers of biotin status is necessary to fill this knowledge gap. Here, we used an outpatient feeding protocol to create states of biotin deficiency, sufficiency and supplementation in sixteen healthy men and women. A total of twenty possible markers of biotin status were assessed, including the abundance of biotinylated carboxylases in lymphocytes, the expression of genes from biotin metabolism and the urinary excretion of biotin and organic acids. Only the abundance of biotinylated 3-methylcrotonyl-CoA carboxylase (holo-MCC) and propionyl-CoA carboxylase (holo-PCC) allowed for distinguishing biotin-deficient and biotin-sufficient individuals. The urinary excretion of biotin reliably identified biotin-supplemented subjects, but did not distinguish between biotin-depleted and biotin-sufficient individuals. The urinary excretion of 3-hydroxyisovaleric acid detected some biotin-deficient subjects, but produced a meaningful number of false-negative results and did not distinguish between biotin-sufficient and biotin-supplemented individuals. None of the other organic acids that were tested were useful markers of biotin status. Likewise, the abundance of mRNA coding for biotin transporters, holocarboxylase synthetase and biotin-dependent carboxylases in lymphocytes were not different among the treatment groups. Generally, datasets were characterised by variations that exceeded those seen in studies in cell cultures. We conclude that holo-MCC and holo-PCC are the most reliable, single markers of biotin status tested in the present study.

Dietary biotin requirement for growth of juvenile zebrafishDanio rerio(Hamilton-Buchanan)

This study was conducted to estimate the dietary biotin requirement for maximum growth of zebrafish Danio rerio. Six isonitrogenous and isocaloric purified diets containing 0.031 (biotin-unsupplemented diet), 0.061, 0.263, 0.514, 1.741 and 2.640 mg biotin kg−1 diet were fed in triplicate tanks for a total of 12 weeks to juvenile zebrafish (initial mean body mass 0.13 ± 0.001 g). From 4 weeks of feeding, fish fed diets with ≤0.061 mg biotin kg−1 showed biotin deficiency signs, such as retarded growth and skeletal deformity, was observed on some dead fish. At the end of the study, gill disorders were observed on some fish and liver glycogen accumulation were also observed in fish fed these diets. Fish fed the biotin-unsupplemented diet exhibited a lower final body weight, protein efficiency ratio and feed utilization than the fish fed the biotin-supplemented diets, whereas the highest values were observed with the diet containing 0.51 mg biotin kg−1 diet (P < 0.05). A linear relationship (r2 = 0.77; P < 0.0001) was observed between whole-body biotin content and dietary biotin level. A broken-line analysis indicated that the optimum dietary biotin content for maximal growth expressed as final body weight is 0.51 mg kg−1 diet.

Effects of biotin on growth performance and foot pad dermatitis of starter White Pekin ducklings

1. An experiment with 9 dietary supplemental biotin concentrations (0, 0·03, 0·06, 0·09, 0·12, 0·15, 0·18, 0·21, 1·5 mg biotin/kg) was conducted to study the effects of supplementary dietary biotin on growth performance and foot pad dermatitis (FPD) of White Pekin ducklings from hatch to 21 d of age. 2. One-d-old male Pekin ducklings (n = 576) were randomly divided into 9 dietary treatments, each containing 8 replicate pens with 8 birds per pen. Final weight, feed intake and body weight gain increased with increasing dietary biotin levels from hatch to 21 d of age. No differences were observed in feed conversion ratio. 3. The supplemental biotin requirement of ducklings for optimal body weight gain was estimated to be 0.180 mg/kg. 4. At 28 d of age, dehydration, cracks, bleeding and scab, and ulceration were observed in biotin-deficient ducks. The external scores for FPD decreased from 17·50 to 1·00 with increasing dietary biotin. It was concluded that supplemental dietary biotin should not be less than 0·21 mg/kg to minimise the incidence of FPD.