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Biofilm formation by Aspergillus flavus and Aspergillus niger: Influence of cultural conditions and their controls
Abstract
Aspergillus organisms have biofilm-forming abilities which make their control with some routine food-contact sanitizers or antifungal agents, more complicated. Studies on biofilm forming abilities of Aspergillus spp and its control are limited. This study was designed to investigate biofilm development by isolates of Aspergillus flavus and Aspergillus niger from meat tables in meat markets and abattoirs in Ibadan. Also, variations in cultural conditions, Lactobacillus rhamnosus GG, and sodium hypochlorite were assessed as measures for their control.
Laboratory stock cultures of A. flavus and A. niger from abattoir environment were cultured by pour-plate method at 105 dilution on Sucrose-Potato dextrose agar, supplemented with streptomycin, and incubated at 26oC for five days, and organisms were enumerated using pre-described standard microbiological methods. The influence of two sugars (sucrose and fructose), at 0.2% and 0.4% concentrations; sodium hypochlorite (NaOCl) at 0.05% and 0.5% concentrations, and Lactobacillus rhamnosus GG at 108 and 104 concentrations were investigated on biofilm development by A. niger (n=2) and A. flavus (n=2) isolates, using Crystal Violet Binding Assay. Biofilm development using overnight grown culture was done in 96-well micro-titer plates, while the biofilm mass was determined by measuring the absorbance at 600 nm. An un-inoculated broth served as control. The experiment was done in at least three replicates. Data were analysed using ANOVA at α0.05.
A. flavus (0.10±0.02) significantly produced a higher biofilm mass than A. niger (0.09±0.01). There was significant increase in biofilm mass with the addition of sucrose and fructose, with more biofilm mass (0.14±0.08 for sucrose and 0.11±0.03 for fructose) observed at 0.2% concentration. Lactobacillus rhamnosus GG significantly decreased biofilm mass of A. flavus (0.07±0.01) and A. niger (0.06±0.00) when compared to the inoculated broth culture without lactic acid bacteria (0.09±0.01). There was a significant reduction in biofilm mass with both 0.05% and 0.5% sodium hypochlorite, with the highest reduction seen with 0.5% concentration at 24 hr. A significant decrease in biofilm mass was observed for A. niger (106) with 0.5% concentration of NaOCl at 24 hr (0.07±0.01) when compared to control (0.09±0.01). Similar results were obtained across species at 24 and 72 hr of incubation. A lower biofilm mass was also formed at 11oC (0.07±0.01) when compared with 28oC (0.10±0.01).
Sodium hypochlorite suppressed biofilm development, thus showing potentials for eliminating Aspergillus biofilms from meat tables in commercial markets, while Lactobacillus rhamnosus GG may be employed as an additive in meat and meat products processing.
... The microplate was once again washed three times with PBS following incubation. After adding ethanol to each well (Ogundijo, 2017), (ELISA) reader, the wells' 450 nm readings were obtained, and the OD was noted for each well. ...
... The biofilm mass was higher in (A, B, and C) isolates of this mold with high significant differences (P≤0.01), as shown in (Table 5 and Figure 8), respectively. This result was in agreement with other studies (Ogundijo, 2017). The reason behind these results may be attributable to the ability of A. flavus to utilize more protein. ...
... Foodborne pathogens are not limited to bacteria, viruses, or parasites; fungi also contribute to foodborne diseases by releasing their toxins in food, especially Aspergillus sp. 74,75 Ismail et al 76 found out that meat and meat products in Egypt harbour fungi, such as Candida sp., Aspergillus sp., Cladosporium sp., Eurotium sp., Eupenicillium sp., Mucor sp., Geotrichum sp., Rhototorula sp. and Penicillium sp. Meat is exposed to these fungi through improper meat processing, meat handlers' and equipment contamination, and animal harbour. ...
Meat handling is a crucial aspect of public health as it forms complex interactions among humans, animals, and the environment. African meat handlers continue to face various challenges in slaughterhouses that significantly impact their lives and the general public during meat processing. This paper reviews the challenges meat handlers encounter and the associated risks of improper meat handling in various African slaughterhouses. A comprehensive literature search was performed on Science Direct, Web of Science, PubMed, Scopus and Google Scholar. Articles published to investigate the challenges and health risks of meat handling practices in Africa from 1961 to 2022 were included in this review. African meat handlers face socio-economic difficulties, including inadequate returns, unpredictable working environment, market, security, and limited healthcare access. Many meat handlers work informally in unregistered facilities and are not trained by experts on proper meat handling. This results in improper meat handling, raising the possibility of meat contamination by foodborne pathogens like Salmonella sp. and E. coli on slaughter and contact surfaces, hence posing a threat to meat safety and public health. We recommended that governmental, institutional and community-level actions should be used to address the health challenges associated with improper meat handling in Africa. Government and institutional bodies play an important role in supporting and upholding the laws that guide proper meat handling and processing. Meat handlers must be educated on meat safety, handling and storage to ensure meat is safe for consumption.
... Increased level of fungal contamination in food processing environment is expected in time as a result of the biofilm forming abilities of Aspergillus organisms as reported by Ogundijo and Adetunji (2017). ...
Meat contamination in abattoirs and meat markets has been associated with several factors. Of major concern is contamination due to pathogenic microbes present in food processing environments. This study investigated fungal contamination in meat markets and abattoir environments. Four meat markets (Olunloyo, Oja Oba, Olorunsogo, and Olodo) and three abattoirs (Olorunsogo, Akinyele, and University of Ibadan) in Ibadan, Oyo State, Nigeria, were assessed for prevalence of Aspergillus species. Fungi counts were determined by Pour-plate method at 10-5 dilution on Sucrose-Potato Dextrose Agar, supplemented with streptomycin, and incubated at 26ºC for 5 days. Culture and enumeration of Aspergillus flavus and Aspergillus niger from table scrapings (n = 260) and swabs (n=100) of abattoir environment were done using standard microbiological methods. The mean value for the total fungal count (TFC) was 4.46 ± 0.24 log CFUml-1. There were significant differences in the total fungal counts among locations, with Olunloyo market having the highest fungal load (4.73 ± 0.64 log CFUml-1), and the lowest total fungal count was at the University of Ibadan abattoir (4.14 ± 1.29 log CFUml-1). A. niger (30.18 %) was the most frequently isolated fungi, while the least was A. fumigatus (1.0 %). Prevalence of A. flavus was 14.79 %. Other fungi species were A. tamarii, A. terreus, Fusarium compacticum, F. oxysporum, F. proliferum, Penicillium chrysogenum, and P. oxalicum. The study revealed a compromise in food safety in meat producing areas of Ibadan and hence, a need to enhance hygienic standards to improve food safety in these locations.
Background: Aspergillus spp., Scopulariopsis spp., Alternaria spp., Acremonium spp. and Fusarium spp. is reported to be responsible as the causative agent of infection in 2-25% of all cases of onychomycosis. The resistance of three types of azole (triazole) antifungals has increased in cases of infection due to Aspergillus spp. This case report discusses combining ciclopirox olamine and fluconazole in recalcitrant onychomycosis due to Aspergillus spp. as an alternative therapy. Case: A 26-year-old woman complained of yellow fingernails 1 year ago. Solitary geographic hyperpigmented macule, brownish yellow onychodyschromia, onycholysis and subungual debris were observed on the fourth digit of the left manus. On examination of 20% potassium hydroxide, long hyphae, and saboraoud dextrose agar (SDA) culture identified Aspergillus spp. Previous treatment was itraconazole 4 pulses and fluconazole 150 mg/week for 3 months showed no improvement. Ciclopirox olamine for 4 months combined with fluconazole 150 mg/week showed healthy nail matrix growth and negative fungal element on a 20% potassium hydroxide examination after 8 weeks of treatment. Conclusion: Recalcitrant onychomycosis can occur due to resistance to azole antifungals. Administration of topical azoles and ciclopirox combination therapy showed clinical and immunological improvements. Latar belakang: Aspergillus spp., Scopulariopsis spp., Alternaria spp., Acremonium spp. dan Fusarium spp. merupakan kapang nondermatofita tersering yang dilaporkan bertanggung jawab sebagai agen penyebab infeksi pada 2-25% dari semua kasus onikomikosis. Saat ini resistensi tiga jenis antijamur golongan azol (triazol) meningkat pada kasus infeksi akibat Aspergillus spp. dan terapi inadekuat dapat menyebabkan resistensi dan rekurensi. Laporan kasus ini membahas penggunaan kombinasi siklopiroks olamin dan flukonazol pada onikomikosis rekalsitran karena Aspergilus spp. sebagai terapi alternatif. Kasus: Seorang perempuan 26 tahun mengeluh kuku jari tangan menguning sejak 1 tahun lalu. Pada digiti IV manus sinistra didapatkan makula hiperpigmentasi soliter bentuk geografika, onikodiskromia kuning kecoklatan, onikolisis dan subungual debris dengan pemeriksaan kalium hidroksida (KOH) 20% ditemukan hifa-hifa panjang dan kultur saboraoud dextrose agar (SDA) teridentifikasi Aspergillus spp. Riwayat terapi sebelumnya dengan itrakonazol 4 denyut dan flukonazol 150mg/minggu selama 3 bulan tidak menunjukkan perbaikan. Siklopiroks olamin selama 4 bulan dengan melanjutkan flukonazol diberikan dan menunjukkan perbaikan matriks kuku normal dan KOH negatif setelah 8 minggu perawatan. Simpulan: Onikomikosis rekalsitran dapat terjadi karena adanya resistensi terhadap antijamur golongan azol. Pemberian terapi kombinasi golongan azol dan siklopiroks topikal menunjukkan perbaikan klinis serta imunologis.
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