Aspergillus flavus Research Papers - Academia.edu (original) (raw)

The effect of eight organic acids (propionic, acetic, formic, lactic, tartaric, citric, oxalic and malic acids) as antifungal agents on the growth of four fungi (Aspergillus flavus, Penicillium purpurogenum, Rhizopus nigricans and... more

The effect of eight organic acids (propionic, acetic, formic, lactic, tartaric, citric, oxalic and malic acids) as antifungal agents on the growth of four fungi (Aspergillus flavus, Penicillium purpurogenum, Rhizopus nigricans and Fusarium oxysporum) were studied. The high acidity appeared for oxalic acid being 0.14 at the high concentration (10%), while the lowest acidity recorded for propionic acid and acetic acid being 2.71 and 2.56 at the low concentration (5%). It was observed that, there was no relationship between the efficacy of organic acid and its final pH. Acetic acid (10%) has the highest inhibitory effect on A. flavus being 45.21%, but tartaric acid (5%) and citric acid (5%) gave the same lowest inhibition effect (0.42%). The lowest value of mycelium dry weight (MDW) of P. purpurogenum was 5.92 g/l when acetic acid was used (10%), but the highest value was 9.38 g/l when tartaric acid (5%) was used. Formic acid (10%) had a strong effect on the inhibition growth of R. nigricans being 28.65%, similar to propionic acid (10%), acetic acid (10%), lactic acid (10%), tartaric acid (10%) and citric acid (10%) being 26.57%, 26.38%, 26.19%, 23.53% and 24.48%, respectively. But malic acid (5%) and oxalic acid (5%) were having a week effect on R. nigricans being 5.31% and 6.45%, respectively. Lactic acid (10%) has the highest inhibitory effect on F. oxysporum being 34.45% and the lowest value was in the case of tartaric acid (5%) being 1.68%. Four treatments were used to determine aflatoxin B 1 production. The highest inhibition (50%) was observed by R. nigricans in the presence of formic acid (10%). Acetic acid in 10% level inhibited the toxic secretion of A. flavus and P. purpurogenum to become 25% and 40%, respectively. Lactic acid (10%) gave 35% inhibition of toxin production in the presence of F. oxysporum.

Seeds of Jojoba (Simmondsia chinensis (Link.) C.E. Schneider, collected from its plantation raised by Jojoba Research Station, Bahawalpur, Pakistan, were germinated in garden loamy soil and some of the seed and seedling characteristics... more

Seeds of Jojoba (Simmondsia chinensis (Link.) C.E. Schneider, collected from its plantation raised by Jojoba Research Station, Bahawalpur, Pakistan, were germinated in garden loamy soil and some of the seed and seedling characteristics were studied. The seeds of Jojoba are chocolate (mahogeny) brown in colour, ovate in shape and non-endospermic provided with a dorsal longitudinal raphe. Testa is thin but hard. A dense creamy-white mat of unicellular trichomes is present over the surface of the seed. The weight of seed averaged to 895.32 ± 11.62 mg varying from 551 to 1155 mg (CV: 12.98%). The seed weight tended to follow normal distribution. Jojoba seedlings appear to resemble the Chisocheton subtype of Vogel (1980). According to the Garwood (1996) scheme Jojoba seedling may be classed as “Crypto-cotylar hypogeal Reserve type”. The embryo is straight. Cotyledons are massive, shortly petiolate succulent, food-laden, creamy white in colour and semi-ellipsoidal in shape. The outer surface of cotyledons is provided with longitudinally running grooves. In one-month old seedlings, shoot was 10.75 ± 1.05 cm and root 12.8 ± 1.8cm long and there were 9.75 ± 1.18 leaves per seedling. There existed variation with respect to leaf shape. The leaves of basal nodes were obtuse apexed, emarginate or round. The leaves of upper nodes were ovate or oblong or elliptic to lanceolate or oblanceolate in shape with acute apex. Venation appeared to be of brachidodromous type as evident by the grooves on the lamina. Stem and leaves densely pubescent. The trichomes of shoot were of two types – a) multicellular uniseriate trichomes of 2-9 (-11) and b) glandular multicellular uniseriate trichomes with apical cell globose. Some trichomes showed meander like cell wall. The shoot of seedling was thickly encrusted with cuticle and wax. The stomata of anomocytic type were the common one. The inner surface of cotyledons had tetracytic stomata. Some stomata with common subsidiary or no subsidiary also existed on stem and leaf. Leaves of Jojoba are amphistomatic. The occurrence of pericytic stoma besides anomocytic one was extremely rare feature on dorsal foliar surface. The average number of stomata was higher on the lower surface (81.91 ± 1.387 per mm2) than on the dorsal surface (55.98 ± 1.452 per mm2). The stomata were sunken. The size of the stomatal complex (stoma + epicuticular dome) was comparable on the two foliar surfaces. In all, seven fungal species (4 genera) were found to associate with Jojoba seeds and seedlings - Rhizopus stolonifer, Aspergillus niger, A. flavus, A. terreus, A. fumigatus, Fusarium solani and Absidia sp. Absidia sp. only associated with seeds in internalized state.

The natural mycobiota occurring in bee pollen is studied in the present report with special attention to analyze the incidence of fungal species that are potential producers of mycotoxins. A total of 90 ready-to-eat bee pollen samples... more

The natural mycobiota occurring in bee pollen is studied in the present report with special attention to analyze the incidence of fungal species that are potential producers of mycotoxins. A total of 90 ready-to-eat bee pollen samples were analyzed. Eighty-seven samples were collected in stores placed in different Spanish areas and three were from Buenos Aires (Argentina). The statistical results (ANOVA) showed that yeasts and Penicillium spp. were the predominant fungi. With regard to the potential mycotoxin producing species, Penicillium verrucosum, Aspergillus niger aggregate, Aspergillus carbonarius, Aspergillus ochraceus, Aspergillus flavus, Aspergillus parasiticus and Alternaria spp. were found. The last genus was isolated very frequently. The potential ability for producing ochratoxin A (OTA) and aflatoxins B1, B2, G1 and G2 was studied by culturing in vitro the isolates followed by analysis of these mycotoxins in culture extracts by HPLC with fluorescent detection. It was found that 100%, 53.3%, 33.3% and 25% of the isolates of A. carbonarius, A. ochraceus, P. verrucosum and A. niger aggregate, respectively, produced OTA. Moreover, 28.6% of the isolates from the A. flavus plus A. parasiticus group were able to produce aflatoxin B1. Aflatoxin B2 was detected in only 10% of the cultures. Aflatoxins G1 and G2 were not detected in cultures under the assayed conditions. This is the first report carried out on the natural mycobiota occurring in bee pollen in general and on the toxigenic capability of these isolates in particular.

This study was carried to detect the contamination of nut with aflatoxin B1 and the Aspergillus flavuse toxin producer in Iraqi market. Results showed that all the nut samples was contaminated with A. flavus , A. niger, Rhizopus spp and... more

This study was carried to detect the contamination of nut with aflatoxin B1 and the Aspergillus flavuse toxin producer in Iraqi market. Results showed that all the nut samples was contaminated with A. flavus , A. niger, Rhizopus spp and Penecillium spp. Four isolates of A. flavus from 6 produced AFB1 on yeast extract and sucrose broth media. Both ELISA and TLC technique was used to detect the ability of A. flavus isolates for toxin production in broth media and in nut samples. All A. flavus isolates were toxin producer at concentrations 16.2, 16, 12, 12, 5.4 and 5 µg/kg on broth media. All nuts samples showed contaminated with AFB1 at 16.5, 12, 12, 12, 5.4 and 5 µg/kg for the peanut (Czechoslovakia), Almonds (Czechoslovakia), the Arachis hypogaea (china), Prunus dulcis china , Juglans regia (china) and Juglans regia (Czechoslovakia) respectively .

ABSTRACT This study involved evaluation of physicochemical and microbiological changes in dried Pupuru (fermented, smoke dried cassava) balls under storage conditions simulating those currently used by the traditional processors. The aim... more

ABSTRACT This study involved evaluation of physicochemical and microbiological changes in dried Pupuru (fermented, smoke dried cassava) balls under storage conditions simulating those currently used by the traditional processors. The aim was to understand the process of spoilage with a view to reducing the rate. pH ranged from 3 to 4, reducing significantly in cabinet-dried samples from 4.24 to 3.27 after 6 days of storage. Viable counts were in the range of 6–8 log cfu/g. Spoilage microorganisms included aerobic spore-forming and non-sporing bacteria as well as potentially toxigenic moulds like Aspergillus flavus and Penicillium species, which could constitute a health hazard to consumers.

Quantitative losses in various biochemical constituents like capsaicin, carotenes, ascorbic acid, polyphenols, mineral matter, sugars (soluble and insoluble), protein and fat were estimated after the successful growth of Aspergillus... more

Quantitative losses in various biochemical constituents like capsaicin, carotenes, ascorbic acid, polyphenols, mineral matter, sugars (soluble and insoluble), protein and fat were estimated after the successful growth of Aspergillus flavus for 30 days on powdered red pepper. The fungal biomass was measured by ergosterol content and Aflatoxin B1 by HPLC. Amongst the various nutritional constituents evaluated for nutritional losses and changes the highest nutritional loss was reported in total carotenoids (88.55%) followed by total sugars (85.5%). The protein content of the infected sample increased from 18.01 % to 23%. The nutritional profile of chilli powder (Capsicum annum var. sannam L.) shows highest share of total soluble sugars (32.89%) and fiber content (21.05%), followed by protein (18.01%) and fat (13.32%) making it an ideal solid-substrate for mould growth. At the end of incubation the fungal biomass was 192. 25 mg / 100 gram powder, total plate count 17.5 X 10 4 CFU/g and ...

In this research, crude α-amylases associated with the spoilage of cassava (Manihot esculenta) tubers/ product ('eba') were biochemically characterized. They were isolated from five fungi: Aspergillus sp. CSA25, Aspergillus sp. CSA26,... more

In this research, crude α-amylases associated with the spoilage of cassava (Manihot esculenta) tubers/ product ('eba') were biochemically characterized. They were isolated from five fungi: Aspergillus sp. CSA25, Aspergillus sp. CSA26, Aspergillus sp. CSA27, Aspergillus sp. CSA35 and Aspergillus sp. CSA38. The results of the analyses showed that the activities of α-amylase obtained from both sources (cassava tuber/ eba) were optimal at 45°C and pH 5.0. The maximum specific activity (Vmax) of the enzyme was found to be 10 U/mg protein, while its Michaelis-Menten constant (Km) was between 0.37-1.25%w/v. The α-amylase is thermally stable for 1-2 h at optimum temperature and pH (45°C; pH 5.0). A broad range of substrate specificity was expressed by the enzyme for cassava starch-containing products (tapioca flour, garri flour, cassava flour, 1%, w/v); however, potato (Ipomoea batatas) starch, yam (Dioscorea rotundata) flour and cocoyam (Colocasia esculenta) flour were relatively minimally hydrolyzed by the crude α-amylases obtained from Aspergillus spp. that caused spoilage of cassava. Ethylenediamine tetraacetic acid (1 mM EDTA) and Mg 2+ treatment had no significant (p > 0.05) effect on the activities of the amylase, but Na + , K + , Ca 2+ , Fe 3+ , thiourea and 5′,5′-dithiobis-2-nitrobenzoate (1 mM DTNB) enhanced its activities. The fungal α-amylases were most activated by K + and had a salt tolerance of 1-2 M NaCl for 24 h. The fungal α-amylases reported in this study would find useful application in industries like food industry, detergent industry, paper industry, textile industry, pharmaceutical industry, etc where microbial α-amylases would be required for efficient and cost-effective hydrolysis of cassava starch, cassava flour and or its products.

Objectives: Studying the incidence of Aspergillus sp. and Aflatoxins (AFs) contamination in dried fruits collected from local market of Hilla city and other origins. Methods: Intergenic fungi were isolated by direct plate method and were... more

Objectives: Studying the incidence of Aspergillus sp. and Aflatoxins (AFs) contamination in dried fruits collected from local market of Hilla city and other origins. Methods: Intergenic fungi were isolated by direct plate method and were morphologically identified on specified media. AFs production by Aspergillus spp. were screened and determined by thin layer chromatography (TLC) and high performance liquid chromatography (HPLC). Results: Aspergillus spp. represented 93.33% of the total isolated mold species. A. niger was dominant (79.61%) and A. flavus was only 12.5%. Of the total Aspergillus spp. , 54.4% found active aflatoxin B1 (AFB1) and aflatoxin B2 (AFB2) producers among 85.24% belong to A. niger and 14.75% belong to A. flavus. HPLC shows that 100% of dried fruit samples tested positive for AFs. Conclusion: Through our study the mold isolates showed different AFs production behavior that they are able to produce AFB1 and AFB2 at a pH range (3.1 to 4.5), optimum temperature at range (28-32ºC) and low aw for best AFs production and this needs much concern especially with dried fruit storage and treatment conditions.

In-vitro antifungal activity of acetone, methanol and chloroform extracts of Parmotrema tinctorum (Despr.ex.Nyl.) Hale. was investigated against ten plant pathogenic fungi viz. Aspergillus niger, Aspergillus flavus, Aspergillus fumigatus,... more

In-vitro antifungal activity of acetone, methanol and chloroform extracts of Parmotrema tinctorum (Despr.ex.Nyl.) Hale. was investigated against ten plant pathogenic fungi viz. Aspergillus niger, Aspergillus flavus, Aspergillus fumigatus, Alternaria alternata, Fusarium oxysporum, Fusarium solani, Fusarium roseum, Ustilago spp., Albugo candida and Penicillium citrinum , with reference to commercially available synthetic antifungal drug Ketoconazole (positive control) using disk diffusion assay. Methanol extract was most effective against all investigated fungi followed by acetone and chloroform extract. Principal component analysis (PCA) concluded that though Ketoconazole was effective against five of the investigated fungi, the extracts of Parmotrema tinctorum were more effective against rest of the five broad spectrum plant pathogenic fungi (Aspergillus fumigatus,Fusarium solani, Fusarium roseum, Penicillium citrinum and Ustilago spp.).

Aspergillus flavus, A. niger, Penicillium expansum and Rhizopus stolonifer were the most frequently isolated fungi from healthy apple fruits. Alternaria alternata was the most common organism of rotten apple fruits, followed by A. niger,... more

Aspergillus flavus, A. niger, Penicillium expansum and Rhizopus stolonifer were the most frequently isolated fungi from healthy apple fruits. Alternaria alternata was the most common organism of rotten apple fruits, followed by A. niger, A. flavus, P. expansum and R. stolonifer. The prevalent type of decay, brown rot lesion, is caused by R. stolonifer followed by A. flavus, A. niger, A. alternata and P. expansum. Sodium hypochlorite had good curative properties against fruit rots. The main natural mycotoxins produced in rotten apple were patulin and aflatoxins. The optimum temperature for patulin production by P. expansum was 15 °C after 15 days. Complete inhibition of patulin formation was attained using 0.2% lemon oil and > 90% inhibition using 0.05% lemon and 0.2% orange oils. Also significant inhibition (> 90%) of aflatoxin production was observed with 0.2% lemon oil.