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PubMed1994

Clinical reactions to Aspergillus niger in a biotechnology plant: an eight year follow up.

The manufacture of citric acid by fermentation of molasses with Aspergillus niger has previously been described as a cause of occupational asthma in a factory. A longitudinal survey of the workforce of this factory has been carried out from 1984 to 1991. Over this period 160 of the original 278 workers left the workforce, together with 39 of 76 new recruits. Partial enclosure of the process and exhaust ventilation, installed in 1984, was effective in preventing any new cases of occupational asthma over the eight year period, and no new skin sensitisation was detected. Spore counts of A niger averaged about 100 times those in the outside air. Health in the 1984 survey had a striking influence on subsequent retiral; only 11 of the 79 with respiratory symptoms remained in 1991, compared with 90 of the 182 with no symptoms. In conclusion A niger is a weak antigen and simple hygiene measures protect the workforce. Exclusion of recruits with positive skin tests is not necessary if such measures are taken. The survey provided evidence of the selection factors operating within a workforce over this period contributing to retiral of the less healthy.

Aspergillosis, Allergic Bronchopulmonary↗
PubMed1999

Occupational IgE sensitisation to phytase, a phosphatase derived from Aspergillus niger.

OBJECTIVE: Phytase is a phosphatase derived from Aspergillus niger that enhances phosphate bioavailability in the gut, and therefore has been increasingly used as an animal feed additive since the early 1990s. The aim of this study was to assess whether work related respiratory symptoms among workers in a so called premix factory producing animal feed additives, could be due to type I (mediated by immunoglobulin E (IgE) allergic sensitisation to phytase. METHODS: Preparations of specific IgE against phytase as used in the factory were assessed by enzyme immunoassay (EIA) in serum samples of 11 exposed workers who regularly handled the enzyme, in 11 office and laboratory workers of the same plant (non-exposed internal controls), and in 19 laboratory animal workers as external controls. The factory workers also completed a questionnaire on common and work related respiratory symptoms. RESULTS: Depending on the cut off level in the EIA for IgE, and the preparation used as coated allergen, antiphytase sensitisation was found in one to four of the 19 external controls, in one to five of the 11 internal controls, and in four to 10 of the 11 exposed workers. Strongest IgE reactions were found in four exposed workers who reported work related respiratory symptoms, particularly wheezing, and in one internal control who possibly had become sensitised because the structure of the factory building did not preclude airborne exposure in the offices and corridors of the plant. Experiments with inhibition EIA for IgE showed that (a) phytase of another commercial source was only partially cross reactive with phytase as used in the premix factory, and (b) phytase used as an animal feed additive did not cross react with common mould extracts, except for extracts from the species of origin, Aspergillus niger. The amount of IgE binding phytase in Aspergillus niger was estimated to be between 0.1% and 1% of the extractable mould proteins. CONCLUSIONS: Phytase is a potentially important new occupational allergen causing specific IgE immune responses among exposed workers. Such IgE sensitisation could probably be the cause of work related asthmatic and other respiratory symptoms if no effective measures are taken to prevent airborne occupational exposure at sites where phytase is handled, particularly during addition of enzyme preparations to animal feed.

6-Phytase↗
PubMed1999

Allergic bronchopulmonary aspergillosis due to Aspergillus niger without bronchial asthma.

A 65-year-old woman was admitted to our hospital with a dry cough and pulmonary infiltrates. Chest radiograph and CT revealed mucoid impaction and consolidations. Peripheral blood eosinophilia and elevated serum IgE were observed. Aspergillus niger was cultured repeatedly from her sputum, but A. fumigatus was not detected. Immediate skin test and specific IgE (RAST) to Aspergillus antigen were positive. Precipitating antibodies were confirmed against A. niger antigen, but not against A. fumigatus antigen. She had no asthmatic symptoms, and showed no bronchial hyperreactivity to methacholine. Thus, this case was diagnosed as allergic bronchopulmonary aspergillosis (ABPA) without bronchial asthma due to A. niger, an organism rarely found in ABPA. The administration of prednisone improved the symptoms and corrected the abnormal laboratory findings.

Aged↗
PubMed1992

Pulmonary oxalate deposition associated with Aspergillus niger infection. An oxidant hypothesis of toxicity.

Tissue injury by Aspergillus niger infection is associated with the deposition of calcium oxalate crystals. Oxalate is recognized to function as a ligand for numerous metal cations and will react with ferric ion to form a coordination complex. We describe oxalate deposition in the lung of a patient with A. niger infection and quantify surface-complexed Fe3+. Crystals collected from lung tissue demonstrated considerable concentrations of surface iron. In addition, we tested the hypothesis that this surface coordination of Fe3+ by oxalate is associated with increased in vitro oxidant generation. Calcium oxalate crystals (1.0 mg/ml) complexed all available Fe3+ from solutions of ferric chloride to concentrations of as much as 1.0 mM. Oxidant generation in both a chemical and a cellular system, measured as thiobarbituric-acid-reactive products of deoxyribose and chemiluminescence, respectively, increased with coordination of higher concentrations of inorganic iron. We conclude that calcium oxalate associated with A. niger infection complexes iron cations onto the crystalline surfaces and may generate oxidants at the solid-solution interface, which could result in tissue injury.

Aspergillosis↗
PubMed2005

Maintaining high vitamin A supplementation coverage in children: lessons from Niger.

In 1997, the reduction of child mortality became a policy priority for the Government of Niger because Niger's child mortality rate was the highest in the world. The Ministry of Public Health, Helen Keller International (HKI), and UNICEF spearheaded a coalition-building process linking vitamin A deficiency (VAD) control to national child survival goals. An evidence-based advocacy strategy was developed around the child survival benefits of adequate and sustained VAD control with one unambiguous message: "VAD control can avert over 25,000 child deaths per year." As a result, in 1997 Niger became one of the first countries in Africa to effectively integrate vitamin A supplementation into National Immunization Days (NIDs) for polio eradication. The challenge was then to provide children with a second annual dose of vitamin A. This led in 1999 to the first ever National Micronutrient Days (NMDs) in Africa. NMDs are mobilization campaigns in which caregivers are actively encouraged to take their children for the delivery of vitamin A supplements. Since 1999, the combination of NIDs and NMDs has ensured that over 80% of children 6 to 59 months of age receive two vitamin A doses annually. The success of NIDs/NMDs has relied on five pillars: leadership and ownership by the Ministry of Public Health; district-level planning and implementation; effective training and flexible delivery mechanisms; effective social information, communication, and mobilization; and responsiveness and flexibility of Ministry of Public Health and development partners. This successful approach has been widely disseminated, notably through the West African Nutrition Focal Points Network.

Child, Preschool↗
PubMed2006

Expression analysis of alternative oxidase gene (aox1) with enhanced green fluorescent protein as marker in citric acid-producing Aspergillus niger.

In a citric acid-producing filamentous fungus Aspergillus niger WU-2223L, a cyanide- and antimycin A-insensitive and salicylhydroxamic acid-sensitive respiratory pathway functions in the mitochondria besides the cytochrome pathway and is catalyzed by alternative oxidase (AOX). We constructed an A. niger transformant strain AOXEGFP-1 expressing a fusion gene, aox1-egfp, encoding AOX and enhanced green fluorescent protein (EGFP) to visually analyze the expression levels of aox1 without disruption of mycelia. In strain AOXEGFP-1, the localization of the fusion protein AOX-EGFP in the mitochondria was clearly confirmed because the sites of the green fluorescence by AOX-EGFP were in agreement with those of the red fluorescence of the mitochondria stained with MitoTracker Red CMXRos. When strain AOXEGFP-1 was cultivated with antimycin A, which inhibits the cytochrome pathway at the level of cytochrome bc(1) to cytochrome c and increases the expression level of aox1, EGFP fluorescence intensity increased with an increase in AOX activity measured as duroquinol oxidase activity. Moreover, EGFP fluorescence was detected in strain AOXEGFP-1 regardless of the glucose concentration in the cultivation media: for example, when cultivations were performed with 10, 30, 60 and 120 g/l glucose, EGFP fluorescence was usually detected in the mitochondria. These results indicate that aox1 was constitutively expressed regardless of the glucose concentration in A. niger.

Aspergillus niger↗
PubMed2000

Contribution of cyanide-insensitive respiratory pathway, catalyzed by the alternative oxidase, to citric acid production in Aspergillus niger.

In Aspergillus niger, a cyanide (CN)- and antimycin A-insensitive and salicylhydroxamic acid (SHAM)-sensitive respiratory pathway exists besides the cytochrome pathway and is catalyzed by the alternative oxidase (AOX). In this study, A. niger WU-2223L, a citric acid-producing strain, was cultivated in a medium containing 120 g/l of glucose, which is the concentration usually needed for citric acid production, and the effects of 2% (v/v) methanol, an inducer of citric acid, 2 microM antimycin A, and 1 mM SHAM on AOX activities and citric acid production were investigated. The AOX activity, measured as duroquinol oxidase, was localized in the purified mitochondria regardless of the presence of any additives. When WU-2223L was cultivated with antimycin A or methanol, both citric acid production and citric acid productivity, shown as the ratio of production per mycelial dry weight, increased with the increase of both the activity of AOX and the rate of CN-insensitive and SHAM-sensitive respiration. On the other hand, when WU-2223L was cultivated with SHAM, an inhibitor of AOX, the CN-insensitive and SHAM-sensitive respiration was not detected and the citric acid production and the productivity drastically decreased, although mycelial growth was not affected. These results clearly indicated that the CN-insensitive and SHAM-sensitive respiration catalyzed by AOX, localized in the mitochondria, contributed to citric acid production by A. niger.

Aspergillus niger↗
PubMed2001

Molecular cloning and characterization of the fructooligosaccharide-producing beta-fructofuranosidase gene from Aspergillus niger ATCC 20611.

The fopA gene encoding a fructooligosaccharide-producing beta-fructofuranosidase was isolated from Aspergillus niger ATCC 20611. The primary structure deduced from the nucleotide sequence showed considerable similarity to those of two other beta-fructofuranosidases from A. niger, but the fopA gene product had several amino acid insertions and an extra C-terminal polypeptide consisting of 38 amino acids that could not be found in the two others. We could successfully express the fopA gene in S. cerevisiae and the fopA gene product obtained from the culture supernatant of the S. cerevisiae transformant had similar characteristics to the beta-fructofuranosidase purified from A. niger ATCC 20611. However, we could not detect any beta-fructofuranosidase activity in either the culture supernatant or cell lysate when the C-terminal truncated fopA gene product by 38 amino acids was used to transform S. cerevisiae. In western analysis of those samples, there was no protein product that is cross-reacted with anti-beta-fructofuranosidase antibody. These results suggested that the C-terminal region of the fopA gene product consisting of 38 amino acids was essential for the enzyme production.

Amino Acid Sequence↗
PubMedDate not supplied

Invertase production on solid-state fermentation by Aspergillus niger strains improved by parasexual recombination.

Invertase production by Aspergillus niger grown by solid-state fermentation was found to be higher than by conventional submerged fermentation. The haploid mutant strains Aw96-3 and Aw96-4 showed better productivity of various enzymes, as compared to wild-type parental strain A. niger C28B25. Here we use parasexual crosses of those mutants to increase further the productivity of invertase in solid-state fermentation. We isolated both a diploid (DAR2) and an autodiploid (AD96-4) strain, which were able to grow in minimal medium after mutation complementation of previously isolated haploid auxotrophic strains. Invertase production was measured in solid-state fermentation cultures, using polyurethane foam as an inert support for fungal growth. Water activity value (Aw) was adjusted to 0.96, since low Aw values are characteristic in some solid-state fermentation processes. Such diploid strains showed invertase productivity levels 5-18 times higher than levels achieved by the corresponding haploid strains. For instance, values for C28B25, Aw96-3, Aw96-4, DAR2, and AD96-4 were 441, 254, 62, 1324, and 2677 IU/(L x h), respectively. These results showed that genetic recombination, achieved through parasexual crosses in A. niger, results in improved strains with potential applications for solid-state fermentation processes.

Aspergillus niger↗
PubMed2006

Gene transfer between different Trichoderma species and Aspergillus niger through intergeneric protoplast fusion to convert ground rice straw to citric acid and cellulases.

Single-stage direct bioconversion of cellulosic materials to citric acid using intergeneric hybrids obtained from three different Trichoderma species and Aspergillus niger was carried out. The recent results were obtained on the basis of either resistance or sensitivity to one or more of five metal ions, two catabolite repressors, and five antifungal agents, which were used in this study at different concentrations. Sixty-six fusants were isolated after using the three intergeneric protoplast fusion experiments, belonging to two types of intergeneric fusants. Fusants of the first type are heterokaryons (35 fusants). On the other hand, those of the second type are haploids (31 fusants), i.e., they were stable. The present study can be successfully applied in the construction of 14 new genetic fusants, which produced at least 100% more citric acid than the citric acid producer strain A. niger. Out of the fusants, three (1/18, 2/13 and 2/15) showed about a threefold increase of citric acid production in comparison with the parent A. niger strain. Furthermore, studies on DNA content showed that this finding may be submitted on the evidence that citric acid and cellulases production was not correlated with DNA content; however, the productivity depends on specific DNA content.

Antifungal Agents↗
PubMed2000

Solid-state fermentation with Aspergillus niger for cellobiase production.

Aspergillus niger NRRL3 was cultivated in a moist wheat bran and ground corncob solid medium supplemented with inorganic minerals for the production of cellobiase (beta-1,4-glucosidase, EC 3.2.1.21). With this method, A. niger NRRL3 was able to produce a high concentration of cellobiase (215 IU/g of solid substrate) after 96 h of incubation. Temperature and moisture content affected final cellobiase titers. The best conditions for cellobiase production from solid substrate by A. niger NRRL3 were determined to be 70% moisture and 35 degrees C.

Aspergillus↗
PubMed2006

Bioaccumulation and biosorption of chromium by Aspergillus niger MTCC 2594.

Chromium toxicity is of prime concern due to chrome tanning processes in the leather sector. Chrome tanning results in the discharge of toxic levels of chromium causing pollution hazards. Chromium levels of Cr(III) and Cr(VI) were high above permissible limits in chrome samples after chrome tanning. The potential of Aspergillus niger MTCC 2594 to accumulate chromium as well as its biosorption capacity is investigated in this study. Bioaccumulation of Cr(III) and Cr(VI) in the spent chrome liquor has resulted in a 75-78% reduction of the initial Cr content in 24-36 h. A. niger biomass is found to be very effective in the biosorption of Cr(III) and Cr(VI) in spent chrome liquor. Maximum adsorption of 83% for biosorption of Cr(III) at 48 h and 79% of Cr(VI) at 36 h in spent chrome liquor is observed. The biosorption characteristics fit well with Langmuir and Freundlich isotherms and the adsorption parameters are evaluated. The biosorption of Cr also follows Lagergren kinetics. A. niger biomass is effectively used for the biosorption of chromium with 79-83% Cr removal in 36-48 h.

Adsorption↗
PubMed1994

Characterization of hydrogen peroxide and superoxide degrading pathways of Aspergillus niger catalase: a steady-state analysis.

The oxidized intermediates generated upon exposure of Aspergillus niger catalase to hydrogen peroxide and superoxide radical fluxes were examined with UV-visible spectrophotometry. Hydrogen peroxide and superoxide radical were generated by means of glucose/glucose oxidase and xanthine/xanthine oxidase systems. Serial overlay of absorption spectra in the Soret (350-450 nm) and visible regions (450-700 nm) showed that the decomposition of hydrogen peroxide by the catalase of Aspergillus niger can proceed through one of two distinct pathways: (i), the normal "catalatic" cycle consisting of ferric catalase-->Compound I-->ferric catalase; (ii), a longer cycle where superoxide radical transforms Compound I to Compound II which is then converted to the resting ferric enzyme via Compound III. The latter sequence of reactions ensures that the catalase of Aspergillus niger restores entirely its activity upon exposure to low levels of superoxide radicals due to the actions of oxidases.

Aspergillus niger↗
PubMed1998

Response to conjugate Haemophilus influenzae B vaccine among infants in Niamey, Niger.

Despite near elimination of Haemophilus influenzae b (Hib) meningitis from several industrialized countries following introduction of conjugate Hib vaccines into infant immunization schedules, Hib remains a major cause of meningitis and pneumonia in resource-poor countries. In Niger, Hib causes nearly 200 cases of meningitis per 100,000 children < one year of age, and > 40% of cases are fatal. We evaluated the immunogenicity of Hib polysaccharide-tetanus toxoid conjugate vaccine (PRP-T) administered in the same syringe as diphtheria-tetanus-pertussis (DTP) vaccine among infants in Niger. Infants were randomized into group 1 (PRP-T at six, 10, and 14 weeks), group 2 (PRP-T at 10 and 14 weeks), or a control group (meningococcal A/C polysaccharide vaccine). By 14 weeks of age, all subjects in groups land 2 had > or = 0.15 microg/ml of anti-PRP antibody, and 82% versus 76% had > or = 1.0 microg/ml of antibody (P=not significant). By nine months of age the proportion of infants with > or = 0.15 and > or = 1.0 microg/ml was group I=97% and 76%; group 2=93% and 67%; controls=10% and 2.6%. Four weeks after the first, second, and third doses of PRP-T, infants in group 1 showed geometric mean titers (GMTs) of 0.19, 3.97, and 6.09 microg/ml while infants in group 2 had GMTs of 2.40 and 4.41 microg/ml four weeks after the delayed first and second doses. Both PRP-T groups had significantly higher GMTs at 18 weeks and nine months of age than infants in the control group. The Hib PRP-T vaccine was immunogenic in infants in Niger. The strong response after PRP-T was initiated one month after the first DTP vaccination may reflect carrier priming. Two dose schedules of PRP-T should be given serious consideration, particularly if their reduced cost permits vaccine introduction that would be otherwise unaffordable.

Antibodies, Bacterial↗
PubMed1998

[Ultrasonographic fetal biometry charts in Niger].

Ultrasound scanning to confirm fetal growth is an essential part of prenatal screening and depends on comparison with biometric reference charts. Charts for ultrasound scanning in Niger were established at the Poudriere Hospital in Niamey between 1994 and 1997. A total of 5,197 measurements were made on 736 fetuses to obtain 50 values for biparietal diameter, transverse abdominal diameter, and femoral length between the 14th and 41st weeks from the last menses. Each parameter was presented with dispersion and compared with similar findings from other series to establish reference charts for the population of Niger. Transverse abdominal fetal diameter in Niger appeared to be below normal. These charts establish a local reference at a given time but will require revision in the future.

Biometry↗
PubMed2000

Can hTNF-alpha be successfully produced and secreted in filamentous fungus Aspergillus niger?

A gene-fusion expression strategy was applied for the heterologous expression of hTNF-alpha in A. niger AB1.13. The TNF-alpha gene was fused with the A. niger glucoamylase GII form as a carrier-gene, behind its transcription control and secretion signal. The protein was expressed in the cells in the form of a glucoamylase-fusion protein, but was not present in the culture medium. From the expression of two hTNF-alpha analogues, LK 811 (Cys95/148) and LK 802 (Cys95/148, His107/108) respectively, we concluded that oligomerisation was not the critical point for secretion of hTNF-alpha in A. niger, but more probably improper folding already at the stage of monomer formation, or even incorrect processing of the molecule during the secretion pathway.

Amino Acid Sequence↗
PubMed2000

Expression of human lymphotoxin alpha in Aspergillus niger.

A gene-fusion expression strategy was applied for heterologous expression of human lymphotoxin alpha (LTalpha) in the Aspergillus niger AB1.13 protease-deficient strain. The LTalpha gene was fused with the A. niger glucoamylase GII-form as a carrier-gene, behind its transcription control and secretion signals. Special attention was paid to the influence of different codon usage on secretion of protein. In the case of human tumor necrosis factor alpha (TNFalpha) a dramatic change of secretion has been observed when human cDNA sequence was used instead of synthetic E. coli biased codons. In the case of LTalpha such a change of codon usage brought improvement at the RNA level, however, no increase in the quantity of secreted protein was observed, due to the proteolitic activity of the host organism. The estimated yield of secretion of LTalpha from A. niger into the soya medium was 50 pg l(-1) of culture.

Artificial Gene Fusion↗
PubMed2001

Characterization of a novel allele of glucose oxidase from a Korean wild type strain of Aspergillus niger.

We have identified a novel allele of the glucose oxidase (GO, EC1.1.3.4) gene (GO) from a Korean wild type strain of Aspergillus niger, ACMO4, with an increased GO activity in culture filtrate. Southern blot analyses of GO from ACMO4 (GO-ACMO4) revealed that the gene was present as a single copy in the genome of A. niger. However, its sequence differs from that of GO from A. niger ATCC 9029 (GO-ATCC9029). GO-ACMO4 appears to be a functional gene based on the fact that it is enzymatically active when heterologously expressed in yeast. Sequence comparisons of the coding region of GO-ACMO4 revealed 16 nucleotide changes that resulted in four amino acid substitutions; T432D, G517D, G530S, and Q542R. The GO proteins from both ATCC 9029 and ACMO4 were heterologously expressed, purified, and compared biochemically. The two enzymes showed no difference in their apparent Km value for glucose (30 mM), but the Vmax of GO-ACMO4 (515.6 unit/mg) was 10% higher than that of GO-ATCC 9029, resulting in a 10% higher specific activity.

Alleles↗