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Nleya N, Ngoma L, Adetunji MC, Mwanza M. Biodiversity of Aflatoxigenic Aspergillus Species in Dairy Feeds in Bulawayo, Zimbabwe. Front Microbiol 2021; 11:599605. [PMID: 33552013 PMCID: PMC7859627 DOI: 10.3389/fmicb.2020.599605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 12/11/2020] [Indexed: 11/17/2022] Open
Abstract
The presence of molds, especially certain species of Aspergillus, in food commodities may contribute to aflatoxin contamination. The aim of this study was to determine the biodiversity of Aspergillus species in dairy feeds from farms in select locations in Zimbabwe and assess their aflatoxin production potential using a polyphasic approach. A total of 96 feed samples were collected, which consisted of dairy feed concentrate, mixed ration, brewers’ spent grain, and grass from 13 farms during the dry season (August–October, 2016) and the following rainy season (January–March, 2017). A total of 199 presumptive isolates representing four sections from genus Aspergillus (Nigri, Fumigati, Flavi, and Circumdati) were recovered from the feeds. Section Flavi, which includes several aflatoxin producers, constituted 23% (n = 46) of the isolates. Species from this section were A. flavus, A. nomius, A. oryzae, A. parasiticus, and A. parvisclerotigenus, and 39 (84.4%) of these showed evidence of aflatoxin production in plate assays. Of the 46 section Flavi isolates examined, some lacked one or more of the five targeted aflatoxin cluster genes (aflD, aflR, aflS, aflM, and aflP). The presence of the five genes was as follows: aflD (76.9%), aflR (48.7%), aflS (74.4%), aflM (64.1%), and aflP (79.5%). This study highlights the species diversity of aflatoxigenic fungi that have the potential to contaminate different types of feed for dairy cows. Our findings underscore the importance of preventing contamination of feedstuffs by these fungi so that aflatoxins do not end up in the diets of consumers.
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Affiliation(s)
- Nancy Nleya
- Department of Animal Health, Northwest University, Mmabatho, South Africa.,Department of Applied Biology and Biochemistry, National University of Science and Technology, Bulawayo, Zimbabwe
| | - Lubanza Ngoma
- Department of Animal Health, Northwest University, Mmabatho, South Africa.,Food Security and Food Safety Niche Area, Northwest University, Mmabatho, South Africa
| | - Modupeade C Adetunji
- Department of Animal Health, Northwest University, Mmabatho, South Africa.,Department of Biological Sciences, Trinity University, Lagos, Nigeria
| | - Mulunda Mwanza
- Department of Animal Health, Northwest University, Mmabatho, South Africa.,Food Security and Food Safety Niche Area, Northwest University, Mmabatho, South Africa
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Nucleic acid amplification free biosensors for pathogen detection. Biosens Bioelectron 2020; 153:112049. [DOI: 10.1016/j.bios.2020.112049] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Revised: 01/21/2020] [Accepted: 01/23/2020] [Indexed: 12/11/2022]
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Rasheed U, Wu H, Wei J, Ou X, Qin P, Yao X, Chen H, Chen AJ, Liu B. A polyphasic study of Aspergillus section Flavi isolated from corn in Guangxi, China- a hot spot of aflatoxin contamination. Int J Food Microbiol 2019; 310:108307. [PMID: 31476582 DOI: 10.1016/j.ijfoodmicro.2019.108307] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 08/14/2019] [Accepted: 08/16/2019] [Indexed: 01/22/2023]
Abstract
Aspergillus section Flavi is widely known as a potential threat to contaminate agricultural products and food commodities. In this study, a polyphasic approach consisting of micro- and macro-morphological, chemical and molecular features, was applied to survey the Aspergillus section Flavi population in corn collected from Guangxi, China. Based on multigene phylogenies as well as morphological observations, Aspergillus flavus (192/195), A. arachidicola (1/195), A. pseudonomius (1/195) and A. novoparasiticus (1/195) were found to be the predominant section Flavi population. Among them, 31 representative isolates were selected for mycotoxin determination. The results showed that Aspergillus flavus chemotype I was most common, chemotype IV was also detected with low incidence and low CPA amounts, while chemotypes II and III were absent. Other tested species including A. arachidicola, A. pseudonomius, and A. novoparasiticus produced all types of aflatoxins, but none of them produced CPA. The polyphasic approach applied in this study permitted reliable understanding of the prevailing Aspergillus section Flavi population and their mycotoxin profiles. Knowledge of the prevailing section Flavi population will aid in developing a sustainable strategy to mitigate the effects of aflatoxin contamination. This study suggests that CPA contamination of food should be considered while conducting mycotoxigenic surveys of food commodities, and the same should be considered while planning a bio-control strategy to control aflatoxin contamination.
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Affiliation(s)
- Usman Rasheed
- Institute of Applied Microbiology, College of Agriculture, Guangxi University, Nanning 530005, China
| | - Hao Wu
- Institute of Applied Microbiology, College of Agriculture, Guangxi University, Nanning 530005, China
| | - Jinfan Wei
- Institute of Applied Microbiology, College of Agriculture, Guangxi University, Nanning 530005, China
| | - Xiaoyun Ou
- Institute of Applied Microbiology, College of Agriculture, Guangxi University, Nanning 530005, China
| | - Peisheng Qin
- Institute of Applied Microbiology, College of Agriculture, Guangxi University, Nanning 530005, China
| | - Xiaohua Yao
- Institute of Applied Microbiology, College of Agriculture, Guangxi University, Nanning 530005, China
| | - Han Chen
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100193, China
| | - Amanda Juan Chen
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100193, China.
| | - Bin Liu
- Institute of Applied Microbiology, College of Agriculture, Guangxi University, Nanning 530005, China.
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Metal Ions in Activated Carbon Improve the Detection Efficiency of Aflatoxin-Producing Fungi. Toxins (Basel) 2019; 11:toxins11030140. [PMID: 30832301 PMCID: PMC6468837 DOI: 10.3390/toxins11030140] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Revised: 02/08/2019] [Accepted: 02/20/2019] [Indexed: 01/23/2023] Open
Abstract
Aflatoxins (AF), produced by several Aspergillus species, are visible under ultraviolet light if present in high amounts. AF detection can be improved by adding activated carbon, which enhances the observation efficiency of weakly AF-producing fungi. However, commercial activated carbon products differ in their characteristics, making it necessary to investigate which characteristics affect method reproducibility. Herein, the addition of 10 activated carbon products resulted in different AF production rates in each case. The differences in the production of aflatoxin G₁ (AFG₁) were roughly correlated to the observation efficiency in the plate culture. Trace element analysis showed that the concentrations of several metal ions differed by factors of >100, and the carbons that most effectively increased AFG₁ production contained higher amounts of metal ions. Adding 5 mg L-1 Fe or Mg ions increased AFG₁ production even without activated carbon. Furthermore, co-addition of both ions increased AFG₁ production stably with the addition of carbon. When varying the concentration of additives, only AFG₁ production increased in a concentration-dependent manner, while the production of all the other AFs decreased or remained unchanged. These findings suggest that a key factor influencing AF production is the concentration of several metal ions in activated carbon and that increasing AFG₁ production improves AF detectability.
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Adetunji MC, Ngoma L, Atanda OO, Mwanza M. A polyphasic method for the identification of aflatoxigenic Aspergilla from cashew nuts. World J Microbiol Biotechnol 2019; 35:15. [PMID: 30607686 DOI: 10.1007/s11274-018-2575-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Accepted: 12/07/2018] [Indexed: 02/04/2023]
Abstract
The invasion of food by toxigenic fungi is a threat to public health. This study aimed at enumerating the microbial profile, detection of aflatoxin producing genes and quantification of the levels of aflatoxin contamination of cashew nuts meant for human consumption. A polyphasic method of analysis using newly formulated β-Cyclodextrin Neutral Red Desiccated coconut agar (β-CDNRDCA) and Yeast Extract Sucrose agar (YES) with Thin Layer Chromatography (TLC), Polymerase Chain Reaction (PCR) and High Performance Liquid Chromatographic (HPLC) method was adopted in determining the aflatoxigenic potential of the isolates, the presence of aflatoxin biosynthetic gene (aflM, aflD, aflR, aflJ omt-A) and estimation of the total aflatoxin content of the nuts. The fungal counts ranged from 2.0 to 2.4 log10cfu/g and sixty-three fungal isolates belonging to 18 genera and 34 species were isolated. The Aspergillus spp. were the most frequently isolated (50.79%) while Trichoderma spp. (1.59%) were the least. and fluorescence production was enhanced on the newly formulated β-CDNRDCA by the aflatoxigenic species. The aflD gene was amplified in all the isolates while aflM, aflR and aflJ gene were each amplified in 77.77% of the isolates and omt-A gene in 70.37%. The aflatoxin content of the nuts ranged from 0.03 to 0.77 µg/kg and were below the 4 µg/kg EU recommended limit for total aflatoxins. The present work confirms that a single method of analysis may not be sufficient to screen for the presence of aflatoxins in foods, as with a combination of different methods.
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Affiliation(s)
- Modupeade C Adetunji
- Department of Animal Health, School of Agriculture, Faculty of Natural and Agricultural Sciences, North-West University, Mafikeng Campus, Private Bag X2046, Mmabatho, 2735, South Africa. .,Department of Biological Sciences, McPherson University, P.M.B. 2094, Seriki Sotayo, Abeokuta, Ogun State, Nigeria.
| | - Lubanza Ngoma
- Department of Animal Health, School of Agriculture, Faculty of Natural and Agricultural Sciences, North-West University, Mafikeng Campus, Private Bag X2046, Mmabatho, 2735, South Africa.,Food Security and Food Safety Niche Area, North-West University, Private Bag X2046, Mmabatho, 2735, South Africa
| | - Olusegun O Atanda
- Department of Biological Sciences, McPherson University, P.M.B. 2094, Seriki Sotayo, Abeokuta, Ogun State, Nigeria
| | - Mulunda Mwanza
- Department of Animal Health, School of Agriculture, Faculty of Natural and Agricultural Sciences, North-West University, Mafikeng Campus, Private Bag X2046, Mmabatho, 2735, South Africa.,Food Security and Food Safety Niche Area, North-West University, Private Bag X2046, Mmabatho, 2735, South Africa
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Morphological Changes of Conidiogenesis in Two Aspergillus Species. JOURNAL OF PURE AND APPLIED MICROBIOLOGY 2018. [DOI: 10.22207/jpam.12.4.40] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
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Detection of Aflatoxigenic and Atoxigenic Mexican Aspergillus Strains by the Dichlorvos⁻Ammonia (DV⁻AM) Method. Toxins (Basel) 2018; 10:toxins10070263. [PMID: 29954142 PMCID: PMC6070877 DOI: 10.3390/toxins10070263] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2018] [Revised: 06/24/2018] [Accepted: 06/25/2018] [Indexed: 11/16/2022] Open
Abstract
The dichlorvos⁻ammonia (DV⁻AM) method is a sensitive method for distinguishing aflatoxigenic fungi by detecting red (positive) colonies. In this study, the DV⁻AM method was applied for the isolation of aflatoxigenic and atoxigenic fungi from soil samples from a maize field in Mexico. In the first screening, we obtained two isolates from two soil subsamples of 20 independent samples and, in the second screening, we obtained two isolates from one subsample of these. Morphological and phylogenic analyses of the two isolates (MEX-A19-13, MEX-A19-2nd-5) indicated that they were Aspergillus flavus located in the A. flavus clade. Chemical analyses demonstrated that one isolate could produce B-type aflatoxins, while the other produced no aflatoxins. These results demonstrate that the DV⁻AM method is useful for the isolation of both aflatoxigenic and atoxigenic Aspergilli.
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Light-Irradiation Wavelength and Intensity Changes Influence Aflatoxin Synthesis in Fungi. Toxins (Basel) 2018; 10:toxins10010031. [PMID: 29304012 PMCID: PMC5793118 DOI: 10.3390/toxins10010031] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Revised: 12/25/2017] [Accepted: 01/03/2018] [Indexed: 01/10/2023] Open
Abstract
Fungi respond to light irradiation by forming conidia and occasionally synthesizing mycotoxins. Several light wavelengths, such as blue and red, affect the latter. However, the relationship between light irradiation and mycotoxin synthesis varies depending on the fungal species or strain. This study focused on aflatoxin (AF), which is a mycotoxin, and the types of light irradiation that increase AF synthesis. Light-irradiation tests using the visible region indicated that blue wavelengths in the lower 500 nm region promoted AF synthesis. In contrast, red wavelengths of 660 nm resulted in limited significant changes compared with dark conditions. Irradiation tests with different intensity levels indicated that a low light intensity increased AF synthesis. For one fungal strain, light irradiation decreased the AF synthesis under all wavelength conditions. However, the decrease was mitigated by 525 nm low intensity irradiation. Thus, blue-green low intensity irradiation may increase AF synthesis in fungi.
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