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Mycoflora and Public Health Risks of Smoked Fish Sold in Port Harcourt Markets, Nigeria

Akani Nedie Patience*, Nwankwo Chidiebele Emmanuel Ikechukwu

Department of Microbiology, Rivers State University, Nkpolu-Oroworukwo, Port Harcourt, 500272 Rivers State, Nigeria

Abstract: Fish is a preferred source of protein globally, especially in developing countries like Nigeria. It is a savoured protein source in the Niger Delta, including Port Harcourt. Smoking is used to preserve fish by reducing its moisture content with a view to improved shelf life. This study aimed at determining the Mycoflora and the Public Health risks of smoked fish sold in Port Harcourt Markets. A total of 54 fish samples were collected from three strategic markets; Mile one, Oil Mill and Creek Road markets. Fish collected consists of 6 different species; Gadus morhua, Pseudotolithus typhus, Lutijanus goreensis, Ethalmosa fimbriata, Pseudotolithus senegalensis and Dasyatis pastinaca. All samples were grouped accordingly. Mycological study of fish samples was done using standard methods on Sabouraud Dextrose Agar. There was a significant difference in the mycoflora counts of smoked fish from different markets (p<0.05). Fungal load ranged from 1.23±0.08 x10³ sfu/g in Lutjanus goreensis to 8.89±0.10 x 103 sfu/g in Gadus morhua, at Creek road market. From Mile 1 market, Lutjanus goreensis still hosted the highest population of 13.25±0.7 x 10³ sfu/g and Dasyatis pastinaca had the least; 0.66±0.01 x 10³ sfu/g. At Oil mill market, Ethalmosa fimbriata hosted 13.23±0.47 x 10³ sfu/g while Gadus morhua had 0.77±0.02 x 10³sfu/g. The fungal load in all fish from all three markets were significantly high for food and calls for attention. Nine fungal genera; Saccharomyces spp, Rhizopus spp, Penicillium spp, Mucor spp, Fusarium spp, Cladosporium spp, Candida spp, Absidia spp and Aspergillus spp, were isolated. All six fish species studied recorded more than 50 % occurrence of fungal species in all the markets. The mycoflora of smoked fish sold in Port Harcourt markets suggest significant public health risks. The need for improved storage and handling of this important protein source is high towards reduced public health risk. Proper preparation method, such as boiling, is strongly advocated.

Keywords: Mycoflora, public health, risks, smoked fish, port harcourt, markets

Received May 04, 2019; Revised June 22, 2019; Accepted July 11, 2019

Citation: Akani Nedie Patience, Nwankwo Chidiebele Emmanuel Ikechukwu, Mycoflora and Public Health Risks of Smoked Fish Sold in Port Harcourt Markets, Nigeria. American Journal of Microbiological Research, 7 (3). 78-82. January 2019. doi:10.12691/ajmr-7-3-2

1. Introduction

The Niger Delta Nigeria is home of majority of Nigeria’s water bodies [1]. As expected, sea food forms a major part of the diet in this region. Port Harcourt is the current capital of Rivers State, a prominent state in the Delta. A travel through the markets in this oil-rich town, reveals a variety of sea foods in the markets. Prominent among these sea foods is fish of various sizes, species and display.

Fish is an important sea food of choice globally [2,3,4,5]. Presently, fish is quoted to constitute 60% total protein in humans [5]. It has been a preferred protein source over the years. The choice of fish as a protein source is owed to certain desirable features [2,4]. Fish is easy to digest, cheap, rich in protein, vitamins and minerals [5,6,7]. Further, the presence of constituents, like omega 3 fatty acid, make fish a preferred protein source [5]. The presence of only 10% cholesterol in fish has also made it a desired flesh protein [7]. Fish consumption has increased because it defiles health, cultural as well as socio-economic barriers [2,6].

Fish is highly perishable [5], in fact the most perishable of muscle foods [2]. Thus, the need for proper fish preservation methods [2,5]. Smoking is a popular preservation method [8]. Smoked fish constitutes up to 45% of all fish consumed in Nigeria [7]. Preferred for convenience and the resulting aroma it leaves on the fish, smoking has been used widely in fish preservation. Primarily, smoking reduces the moisture content of food and thus limiting the activities of spoilage microorganisms [5]. Though very advantageous, smoking has some side effects such as inclusion of Polycyclic Aromatic Hydrocarbons (PAHs) in the preserved food [9].

Numerous studies have questioned the public health safety of smoked fish [2,5,7]. Fish at the point of harvesting possess a notable microbial load in various body parts [3,5]. These studies have isolated microorganisms posing health hazards from smoked fish. The microbial population that contaminates these fish depend on numerous factors such as season [5,7]. The presence of these microorganisms could pose numerous public health risks. Further, smoking as a method of fish preservation could introduce polycyclic aromatic hydrocarbons [9] and yet fail to prevent microbial proliferation [5]. These PAHs have been implicated for various diseases of humans that could lead to mortality.

Food spoilage was not ascribed to fungi previously but fungal species have been shown responsible for spoilage recently [7]. The Mycoflora sums up the total fungal population in a sample. The Mycoflora of smoked fish could pose public health risk(s), especially considering fish consumption method and preparation. Studies have isolated numerous fungi from smoked fungi [5,6,7,8]. Most of these fungi are known to have public health risks based on certain pathogenic attributes. Some fungi produce aflatoxins known to pose severe consequences including being carcinogens and damage organ [7]. Aflatoxins are teratogenic, nephrotoxic, immunotoxic and mutagenic [10]. They have been linked to cases of hepatitis especially in developing countries like Nigeria [5,7]. Nigeria has been described as endemic for hepatitis virus with up to 13% having Hepatitis B and 8 % having Hepatitis C [11]. Several episodes of epidemic and high mortality have been linked to fungal toxins [10]. Further, the immunosuppressing effects of aflatoxins could expose humans to infections such as Human Immunodeficiency Virus (HIV) and tuberculosis [12].

Smoked fish is considered safely preserved and consumed variously. In Nigerian cities, including Port Harcourt, smoked fish is integral to most of delicious dishes. It has been consumed variously; cooked and uncooked. The method of consumption could further bring the health risks to fore, especially when consumed raw. Although preserved and apparently safe from spoilage, smoked fish sometimes appear damp and with moulds. The presence of moulds on smoked fish raises some questions as to the mycological status and consequent public health risk(s) of smoked fish. Numerous studies have successfully established public health risks associated with smoked fish in Nigerian markets [2,5,7,9]. The present study therefore, was aimed at studying the Mycoflora of smoked fish in Port Harcourt markets as a way of establishing the public health risk(s) associated with smoked fish consumption.

2. Materials and Methods

2.1. Study Area

The study area was Port Harcourt, Rivers State. Three (3) popular markets were chosen for the present study. Fish samples were obtained from Mile One, Oil Mill and Creek Road Markets, on coordinates 4.7918°N, 6.9986°E; 4.5121°N, 7.352°E and 4.7582869°N, 7.0208996°E respectively. Markets were considered representative of the entire metropolis and usually the major source of smoked fish in Port Harcourt.

2.2. Sample Collection

A total of 54 smoked fish samples consisting six different species: Gadus morhua (stock fish), Pseudotolithus typhus (Croaker), Lutijanus goreensis (Red snapper), Ethalmosa fimbriata (Bonga fish), Pseudotolithus senegalensis (Broke marriage) and Dasyatis pastinaca (Sting ray) were purchased from the various markets and transported in clean polythene bags to the laboratory for analysis. Each group (market) consisted of eighteen (18) samples used in the study.

2.3. Mycological Studies

Study of the Mycoflora of smoked fish was performed aseptically. Commercially available Sabouraud Dextrose Agar (SDA) (Biolab Laboratories, Hungary) was used. All dilutions were done in sterile normal saline. Standard plate count as in Cheesbrough (2006) [13] was used for isolation and enumeration of fungi.

For each set of 18 market samples, 10 g of smoked fish was weighed onto clean aluminium foil. Then the samples were macerated in 90 ml sterile normal saline using warring blender to give 10⁻¹ dilution as in previous studies [7]. The mixture was diluted serially up to 10⁻⁴ and 0.1 ml of respective solutions pipetted into sterile petri dishes. Then molten SDA, containing penicillin and streptomycin, was poured and allowed to solidify. All set up, in triplicates, were incubated at 28 ⁰C for 5 days. Colonies were then subcultured to obtain pure colonies used for identification. Identification was done using morphological and microscopic features (wet mount) with reference to Practical Mycology Manual for Fungi Identification [7].

2.4. Data Analysis

Analysis of Variance (ANOVA) was used to test all data for significance (p<0.05) using SPSS version 23. Where differences occurred, Duncan’s multiple range test (DMRT) was used to separate the means.

3. Results

A study of the Mycoflora of smoked fish showed numerous fungal genera in all three markets. All six fish species studied, presented with significant fungal load. In creek road market, the highest fungal load (8.89±0.10 x 103 sfu/g) was recorded in Lutjanus goreensis while Gadus morhua had the least load (1.23±0.08 x 103 sfu/g) (Table 1). In Mile 1 market, Lutjanus goreensis still recorded the highest fungal load (13.25±0.70 x103 sfu/g) while Pseudotolithus typhus had the least (0.59±0.06 x 103 sfu/g). However, a look at results from Oil mill market showed that Ethalmosa fimbriata had the highest load (13.23±0.47 x 103 sfu/g) with the Gadus mohua presenting the least load (0.77±0.02 x103 sfu/g) as in Creek road market.

Marked difference in the Mycoflora of the fish in various markets was recorded. Obviously, there was a significant difference (p<0.05) in the Mycoflora of all fish studied across the markets apart from Gadus morhua, where difference was noted only between Creek road and other markets (Table 1).

Further, the percentage occurrence of fungal isolates was studied. Again, an interesting pattern in the occurrence of fungal species was recorded. Nine fungal genera, including Saccharomyces, Rhizopus, Penicillium, Mucor, Fusarium, Cladosporin, Candida, Absidia and Aspergillus species were consistently present in all three market samples. Of the nine genera isolated, Aspergillus spp. (38.33%) closely followed by Penicillium spp. (26.67%) was most abundant in all markets (Figure 1). The least abundant species isolated across the markets however varied. They were Cladosporium spp. (1.67%) in Oil mill, Mucor (2.82%) in Creek road and Rhizopus, Mucor and Cladosporium (1.89% each) in Mile one market.

The distribution of Mycoflora on the fish species was also studied and recorded. Interestingly, none of the fish species hosted all nine fungal species. The highest fungal presence was noted in Ethalmosa fimbriata (Bonga fish), with all species apart from Candida tropicalis present (Table 2). Otherwise, all other fish species studied presented with at least five of all nine fungal species.

Table 1. Fungal Populations (x103 sfu/g) of smoked fishes in the various markets in Port Harcourt

Figure 1. Percentage occurrence of Fungal isolates in the different markets sampled

Table 2. Distribution of fungal isolates in the different fishes sampled

4. Discussion

The fungal population in the smoked fish species in this study varied according to the location of the market and were significantly different (p<0.05). The highest fungal load was recorded in Ethalmosa fimbrata (13.23±0.47 x 103 sfu/g) while the least was recorded in Dasyatis pastinaca (0.66±0.01 x 103 sfu/g) and Gadus morhua (0.77±0.02 x 103 sfu/g). These results are however comparable to that of previous studies conducted in other parts of Nigeria [5,7,14]. Although the safe fungal load for food is at < 10⁶cfu/g [22], the health risk exposed by the present study is enormous. This is based on aflatoxin production and tolerable limit in humans ranging from less than 1 ng/kg body weight in developed countries to about 100 ng/kg body weight in Africa [12]. Several factors have been highlighted to support fungal infestation of fish. Some of the factors include temperature, humidity and handling [5]. Similarly, these factors also enhance aflatoxin production [10]. More worrisome, is the presence of these factors in the study area. Proper insight into the preservation processes leaves a lot to be desired. Harvested fish are preserved in many unhygienic ways due to its high perishability. Efforts are made to keep the temperature at safe levels. This has been achieved by using damp sack to cover as well as mixing with wet weed or green grass [15]. Although for good reasons, these handling practices could increase the Mycoflora of fish. The high Mycoflora in all markets could be blamed on hygiene conditions of all the markets.

Further, smoking is a method of fish drying that applies between 20°C and 30°C [16,17]. This temperature will not deter but may even encourage fungal proliferation as well as toxin production. Fungal growth temperature in the present study was 28°C. This is within the range of temperature obtainable in the traditional drying method. Obviously, this could explain the high fungal load of the fish studied. Also, aflatoxin production is favoured at temperatures between 24°C to 28°C [10]. Previous studies have reported that although smoking is seen as a good preservation method, the resulting fish do not have a good shelf life [7]. Shelf life prolongation is a key consideration in choosing a preservation method. More improved drying methods have been reported with better results and improved shelf life [16,17]. Such methods require more sophisticated procedure in Kilns, using higher temperatures and thus, better results. Fungi are spore-forming and these spores are resistant to heat [5]. These spores are implicated for colonisation and spoilage of dry materials such as smoked fish. Spore propagation could be fostered the more by the poor hygiene practices obtainable in the markets studied. The present study as well as previous studies has noted the display of fish close to dirty drainage gutters in markets leading to contamination of smoked fish [2,5,7,15].

Apart from drying procedure, handling has also been blamed for smoked fish contamination [2,3,5,7,18]. Specifically, the method of displaying these fish may not be proper. Display of fish for sale is mostly done in trays with no allowance for proper aeration. This could increase humidity and thus fungal proliferation as well as aflatoxin production. The study by Adebayo-Tayo et al. [7], also highlighted the crowding of fish on trays for fungal infestation. Further, Port Harcourt is a humid city [19]. Naturally, this could have availed the needed humidity for fungal growth.

The lowest fungal population recorded in Gadus morhua (the normal stock fish) may be due to the method of drying in more regulated Kilns before importation. Apparently, the stock fish has lower proliferation requirements for fungal colonisation. This would explain the significant reduction in fungal load. Conversely, other smoked fish samples are dried in the local Kilns. These drying apparatus may not be able to achieve the temperatures of the more sophisticated Kilns. Thus, fungal load is higher in these locally preserved fish samples.

The Isolation of nine (9) fungal species (including, Saccharomyces, Rhizopus, Penicillium, Mucor, Fusarium, Cladosporium, Candida, Absidia and Aspergillus) in this study calls for concern as to the efficacy of the usual local drying methods and the mycological safety of smoked fish. Although fungal species occurred in varying frequencies, Aspergillus spp. (38.33%) closely followed by Penicillium spp. (26.67%) was most abundant in all markets. This finding is similar to those of other researchers [5,7,14], although they failed to isolate Candida tropicalis and Absidia spp. Fungal growth is supported by adequate moisture beyond 16 % [5,7,20]. Fish preservation by drying aims to remove up to 90 % moisture from the food and mould proliferation is hampered at 10 % moisture [5]. Total Mycoflora load in all fish samples in all markets were high and a source of concern considering their toxin production abilities [12].

The Mycoflora of smoked fish sold in Port Harcourt Markets suggest public health risks. Certain fungal species such as Aspergillus spp. and Penicillium spp have been implicated for public health risks [7]. Aspergillus and Penicillium species have been associated with the production of toxins including aflatoxins and ochratoxins leading to mortality [5,7,20]. With the level of fungal contamination in smoked fish, consumers may also be ingesting these fungal species as well as toxins and metabolites [5,7]. Most likely, the ingestion of these toxins will be above the tolerable dose per body weight per day [12].

5. Conclusion

Smoked fish sold in Port Harcourt presents with high fungal load and could pose significant public health risks. The use of more regulated, sophisticated Kilns would improve the quality of the resulting smoked fish. Further, it is important that fish handlers are educated to imbibe a quality assurance process in the model of the Hazard Analysis Critical Control Points (HACCP). Smoked fish should be adequately cooked prior to consumption to reduce public health risks.

References

[1]   | Ekong, F., Jacob, A., & Ebong, S. Water resource management in the Niger Delta region of Nigeria: The role of physical planning. Int. Rev. Soc. Sci. Human, 3(1), 51. February 2012.
[2]   | Anihouvi, D. G. H., Kpoclou, Y. E., Abdel Massih, M., Iko Afé, O. H., Assogba, M. F., Covo, M., & Mahillon, J. Microbiological characteristics of smoked and smoked–dried fish processed in Benin. Food Science & Nutrition, 7, 1821-1827. April 2019.
[3]   | Adeyemi, O. T., Osilesi, O. O., Onajobi, F., Adebawo, O., & Afolayan, A. J. Stability study of smoked fish, horse mackerel (Trachurustrachurus) by different methods and storage at room temperature. African Journal of Biochemistry Research, 7(6), 98-106. June 2013.
[4]   | Nwankwo, C. E., & Akani, N. P. Bacterial flora of Clarias gariepinus from some selected fish ponds in Port Harcourt. Journal of Environment & Biotechnology Research, 6(2), 208-212. April 2017.
[5]   | Samuel, O., Ifeanyi, O., & Ugochukwu, O. Mycoflora of smoke-dried fish varieties sold in Eke Awka Market in Anambra State, Nigeria. American Journal of Life Science Researches, 3(3), 196-201. August 2015.
[6]   | Sani, F. M., Nasir, I. A., & Torhile, G. Mycological evaluation of smoked-dried fish sold at Maiduguri Metropolis, Nigeria: preliminary findings and potential health implications. European Journal of Health Science, 2(1), 5-10. June 2016.
[7]   | Adebayo-Tayo, B. C., Onilude, A. A., & Patrick, U. G. Mycoflora of smoke-dried fishes sold in Uyo, Eastern Nigeria. World Journal of Agricultural Sciences, 4(3), 346-350. March 2011.
[8]   | Wogu, M. D., & Iyayi, A. D. Mycoflora of some smoked fish varieties in Benin City Nigeria. Ethiopian Journal of Environmental Studies and Management, 4(1), 36-38. January 2011.
[9]   | Tongo, I., Ogbeide, O., & Ezemonye, L. Human health risk assessment of polycyclic aromatic hydrocarbons (PAHs) in smoked fish species from markets in Southern Nigeria. Toxicology reports, 4, 55-61. December 2017.
[10]   | Atanda, O., Makun, H. A., Ogara, I. M., Edema, M., Idahor, K. O., Eshiett, M. E., & Oluwabamiwo, B. F. Fungal and mycotoxin contamination of Nigerian foods and feeds. In Mycotoxin and food safety in developing countries. Intech Open. January 2013.

[11]  
Meka, I. A., Omotowo, B. I., Ijoma, U. N., Okoli, E. V., Nwagha, T. U., Ndu, A. C., & Ugwu, E. O. Zero Prevalence of Hepatitis B and C Coinfection among a Large Cohort of Health care Workers in Enugu, Nigeria: a Cross-sectional Descriptive Study. International Journal of Medicine and Health Development, 23, 171-175. May 2018.

[12]   | World Health Organisation (WHO) Aflatoxins. Food Safety Digest, Department of Food safety and Zoonoses. REF. No.: WHO/NHM/FOS/RAM/18.1. 2018. Available at: https://www.who.int/foodsafety/FSDigest_Aflatoxins_EN.pdf. Accessed 01-06-2019.
[13]   | Cheesebrough, M. Biochemical tests to identify bacteria. District Laboratories Practice in Tropical Countries, 2nd ed. Cambridge university press, Cape Town. pp. 62-70. 2006.
[14]   | Ineyougha, E. R., Orutugu, L. A., &Izah, S. C. Assessment of Microbial Quality of Smoked Trachurustrachurus sold in some Markets of Three South-South States of Nigeria. International Journal of Food Research, 2, 16-23. May 2015.
[15]   | Akande, G. R., & Tobor, J. G. Improved utilization and increased availability of fishery products as an effective control of aggravated animal protein deficiency-induced malnutrition in Nigeria. 10th Annual Conference of the Fisheries Society of Nigeria (FISON) 1: 18-31. November 1993.
[16]   | Likongwe, M. C., Kasapila, W., Katundu, M., & Mpeketula, P. Microbiological quality of traditional and improved kiln smoked catfish (Clarias gariepinus; Pisces; Clariidae) in Lake Chilwa Basin. Food Sscience & Nutrition, 7(1), 281-286. January 2019.
[17]   | Stołyhwo, A., & Sikorski, Z. E. Polycyclic aromatic hydrocarbons in smoked fish–a critical review. Food Chemistry, 91(2), 303-311. June 2005.
[18]   | Sousa, A. K. A. D., Fogaça, F. H. D. S., Araujo, T. D. S., Castro, K. N. D. C., Pereira, a. M. L., Canuto, K. M., & Magalhães, J. A. D.Effect of Alpinia zerumbet essential oil on the shelf life of tambaqui fillets during short-term refrigerator storage. Acta Amazonica, 49(2), 152-161. May 2019.
[19]   | Nwaerema, P., Vincent, O. N., Amadou, C., & Atuma, I. M. (2019). Spatial Assessment of Land Surface Temperature and Emissivity in the Tropical Littoral City of Port Harcourt, Nigeria. International Journal of Environment and Climate Change, 88-103. April 2019.
[20]   | Carlile, M. J., Watkinson, S. C., & Gooday, G. W. The fungi. Gulf Professional Publishing. 2001.
[21]   | Ayeloja, A. A., George, F. O. A., Jimoh, W. A., Shittu, M. O., & Abdulsalami, S. A. Microbial load on smoked fish commonly traded in Ibadan, Oyo State, Nigeria. Journal of Applied Sciences and Environmental Management, 22(4), 493-497. April 2018.
[22]   | Cheesbrough, M. Microbiological test. In: District Laboratory Practice in Tropical Countries Part 2. Cambridge University Press, Cambridge Cape Town. 2002.