Culture of Aspergillus parasiticus in apple juice. I. The influence of sodium benzoate and potassium sorbate on fungal growth and aflatoxin biosynthesis

Sodium benzoate or potassium sorbate (100, 200, 300 and 400 mg/l) were added to cultures of Aspergillus parasiticus NRRL 2999 on apple juice (from syrup) and incubated quiescently at 25 degrees C for 3, 6, 9, 12 or 15 days. The cultures were analyzed for pH, mycelial dry weight and accumulation of aflatoxin B1 and G1. The initial pH of 2.5 remained constant in all instances throughout the incubation period. Sodium benzoate, at all concentrations, suppressed fungal growth and stimulated the biosynthesis of G1, whereas little influence was exerted upon the accumulation of B1. Potassium sorbate stimulated fungal growth at 100 mg/l, while at all concentrations it considerably inhibited toxin production (no detectable amounts of B1 and 3 to 5 times less G1 than in controls). The concentration of G1 surpassed that of B1 without exception.     

Kultur vonAspergillus parasiticus im Apfelsaft

Zusammenfassung Kulturen vonAspergillus parasiticus NRRL 2999 in Apfelsaft (aus Sirup) wurden Natriumbenzoat bzw. Kaliumsorbat (100, 200, 300 und 400 mg/l zugesetzt, danach wurden diese bei 25 °C, 3, 6, 9, 12, oder 15 Tage bebrütet und Myceltrokkengewicht, pH und Konzentration der Aflatoxine B₁ und G₁ bestimmt. Der pH-Anfangswert von 2,5 blieb in allen Fällen während der ganzen Inkubationsdauer unverändert. Natriumbenzoat unterdrückte bei allen getesteten Konzentrationen das Wachstum und förderte die Biosynthese von Aflatoxin G₁, während es die Anhäufung von B₁ wenig beeinflußte. Kaliumsorbat förderte das Wachstum bei 100 mg/kg, doch alle getesteten Konzentrationen inhibierten die Produktion der Toxine erheblich (keine nachweisbaren Mengen von B₁ und 3- bis 5 mal weniger G₁ als in der Kontrollreihe). Ausnahmslos wurde Aflatoxin G₁ stärker als B₁ angehäuft.

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The cultivation ofAspergillus parasiticus on apple juiceI. Influence of sodium benzoate and potassium sorbate on fungal growth and aflatoxin biosynthesis

Summary Sodium benzoate or potassium sorbate (100, 200, 300 and 400 mg/l) were added to cultures ofAspergillus parasiticus NRRL 2999 on apple juice (from syrup) and incubated quiescently at 25 °C for 3, 6, 9, 12 or 15 days. The cultures were analyzed for pH, mycelial dry weight and accumulation of aflatoxin B₁ and G₁. The initial pH of 2.5 remained constant in all instances throughout the incubation period. Sodium benzoate, at all concentrations, supressed fungal growth and stimulated the biosynthesis of G₁, whereas little influence was exerted upon the accumulation of B₁. Potassium sorbate stimulated fungal growth at 100 mg/l, while at all concentrations it considerably inhibited toxin production (no detectable amounts of B₁ and 3 to 5 times less G₁ than in controls). The concentration of G₁ surpassed that of B₁ without exception.

     

Kultur vonAspergillus parasiticus im Apfelsaft II. Einflu? von Butylhydroxyanisol (BHA) and Butylhydroxytoluol (BHT) auf Pilzwachstum and Aflatoxin-Biosynthese

Zusammenfassung Aspergillus parasiticus NRRL 2999 wurde im Apfelsaft (aus Sirup) in Gegenwart von BHA bzw. BHT (100, 200, 300 oder 400 mg/1) bis zu 15 Tage bei 25 °C ruhend bebrütet. Myceltrockengewicht, pH and Konzentrationen der Aflatoxine B₁ und G₁ wurden in dreitägigen Abständen bestimmt. Der pH-Anfangswert von 2,5 blieb durchwegs unverändert. BHA unterdrückte das Wachstum and die Toxinanhäufung in der beobachteten Zeitspanne. Es kam jedoch zu konzentrationsabhängigen Wachstumsverzögerungen und zu früheren Toxin-Höchst-werten als in der Kontrollreihe, was auf eine Anpassung ans Milieu hinweist. BHT führte erst ab 200 mg/l zu einer ca. 25%igen Wachstumshemmung (Löslich-keitsgrenze von BHT zwischen 200 and 300 mg/1) und bei 200 mg/l zur ca. 45%igen Hemmung der Toxinanhäufung. Bei 100 mg/l wirkte BHT fördernd auf die Toxinsynthese (1,90 mal mehr G1 and 6,65 mal mehr B₁ als in der Kontrollreihe). Bei allen getesteten Konzentrationen von BHA bzw. BHT sowie in der Kontrollreihe wurde Aflatoxin G₁ starker als B₁ angehauft.

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The cultivation ofAspergillus parasiticus on apple juice II. Influence of butylated hydroxyanisole and butylated hydroxytoluene on fungal growth and aflatoxin biosynthesis

Summary Aspergillus parasiticus (NRRL 2999) was incubated in apple juice (from syrup), quiescently at 25 °C for up to 15 days in the presence of butylated hydroxyanisole (BHA) or butylated hydroxytoluene (BHT) at concentrations of 100, 200, 300, or 400 mg/l. Mycelial dry weight, pH and concentration of aflatoxin B₁ and G₁ were measured every 3 days with the initial pH of 2.5 remaining unchanged in all samples. BHA suppressed fungal growth and toxin accumulation during the observed incubation period. However, a concentration-dependent growth delay and earlier peaks of toxin accumulation suggested environmental adaptation of the mould. BHT (from 200 mg/l onwards), led to growth inhibition by about 25% (solubility limit of BHT lies between 200 and 300 mg/1), and at a concentration of 200 mg/1, it led to a reduction of toxin accumulation by approximately 45%. At 100 mg/l, however, BHT stimulated aflatoxin production (1.90 times more G, and 6.65 times more B₁ than in the controls). At all tested concentrations of BHA or BHT, as well as in the controls, the accumulation of aflatoxin G₁, without exception, surpassed that of B₁.

     

Prebiotic effects and intestinal fermentation of cereal arabinoxylans and arabinoxylan oligosaccharides in rats depend strongly on their structural properties and joint presence

Scope: Cereal arabinoxylan (AX) is one of the main dietary fibers in a balanced human diet. To gain insight into the importance of structural features of AX for their prebiotic potential and intestinal fermentation properties, a rat trial was performed. Methods and results: A water unextractable AX‐rich preparation (WU‐AX, 40% purity), water extractable AX (WE‐AX, 81% purity), AX oligosaccharides (AXOS, 79% purity) and combinations thereof were included in a standardized diet at a 5% AX level. WU‐AX was only partially fermented in the ceco‐colon and increased the level of butyrate and of butyrate producing Roseburia/E. rectale spp. Extensive fermentation of WE‐AX and/or AXOS reduced the pH, suppressed relevant markers of the proteolytic breakdown and induced a selective bifidogenic response. Compared with WE‐AX, AXOS showed a slightly less pronounced effect in the colon as its fermentation was virtually complete in the cecum. Combining WU‐AX and AXOS caused a striking synergistic increase in cecal butyrate levels. WU‐AX, WE‐AX and AXOS together combined a selective bifidogenic effect in the colon with elevated butyrate levels, a reduced pH and suppressed proteolytic metabolites. Conclusion: The prebiotic potential and fermentation characteristics of cereal AX depend strongly on their structural properties and joint presence.