Printer Friendly

Fungal species associated with the spoilage of some edible fruits in Maiduguri Northern Eastern Nigeria.

Introduction

Fruits and vegetables are vital sources of nutrient to human beings. They give the body the necessary vitamins, fats, minerals and oil in the right proportion for human growth and development. Fruits and vegetables however, have serious challenges to their existence. These include changes in climatic condition, pest, inadequate rainfall and fungal attack. Over the years, there has been an increase in the need to identify and isolate the fungi associated with their spoilage.

Spoilage refers to any change in the condition of food in which the food becomes less palatable, or even toxic; these changes may be accompanied by alterations in taste, smell, appearance or texture. (Paul et-al 1978) Numerous microbial defects (signs and symptoms) of agricultural crops are characterized by the types of microorganism responsible for the deterioration; the process of infection in the case at fungal invasion follows the development of fungal penetrating structure (appresorium). Colonization of fungi is a critical phase in the microbial spoilage of post harvested fruits. The colonization process involves the ability of the microorganism (fungi) to establish itself within the produce (host). This is initiated when fungi (following adhesion and release of enzymes) depolymerises certain specific cell wall polymers (such a protopectin, the cementing substance) of the produce [13]. Susceptibility of fruits and vegetables is largely due to differential chemical composition such as pH and moisture contents. The higher pH (near neutrality) and moisture contents are associated with their greater predisposition to fungal spoilage. The occurrence of fungal spoilage of fruits is also recognized as a source of potential health hazard to man and animals. This is due to their production of mycotoxins (naturally occurring toxic chemical often of aromatic structure) compounds which are capable of including mycotoxicoses in man following ingestion or inhalation. They differ in their degree and manner of toxicity [4].

The contamination of fruits and vegetables by fungi could also be as a result of poor handling practices in food supply chain, storage conditions, distribution, marketing practices and transportation [4].

Fungi affecting Tomatoes (lycopersicum esculentus) includes Fusarium Oxysporium, Fusarium moniliform, Aspergillus niger and Rhizopus Stolonifer. They are responsible for Tomato soft rot, as was isolated by [8]. Result on the percentage incidence and rot shows that Rhizopus Stolonifer caused the greatest rot on tomato fruit. A lot of breading works have been carried on Tomato up to the point where we now have Tomato hybrids that could withstand adverse environmental condition and are resistant to diseases and pests [3].

The preponderance of the isolated moulds from Orange(Citrus sinensis) belongs to Aspergillus species, and this confirms their prevalence in foods and fruits exposed to tropical humid climate thus constituting potential health risks to consumers of this fruit and it's by products [7].

Aspergillus niger, Aspergillus flavus, Rhizopus nigrican, Curvularia lunata, Rhizopus oryzae, Fusarium equiseti and Fusarium moniliforme were responsible for post harvested losses in Pawpaw (Caricapaya) in southern Nigeria [5]. Fungi such as Phytopthora cinnamoni, Aspergillus niger and Candida sp also attack Pineapple (Ananas comosus) [5].

Materials and method

The fruits Caricapaya, lycopersicum esculentus, Citrus sinensis and Ananas comosus both fresh that those with spoilage signs were purchased from three different markets which are Maiduguri Monday Market, custom market and Gidan madara fruit shop in Borno state of Nigeria. A total of forty-four fruits comprising eleven fruits from each fruit type were purchased. Among each of the eleven fruits, there were three infected or spoilt and eight healthy looking fruits. All together there were twelve rotten fruits. The fruits were put in 90% ethanol sterile polyethene bags and transported to the laboratory for analysis.

Isolation of fungi from each of the blemished fruits was carried out using the method of Amusa et.al [1] and Bariyewu et.al [2]. Segments (3-5cm) of tissues from the margins of the rotted fruits were cut with a sterile scalpel and placed on the previously prepared sabouraud dextrose agar in Petri dishes and incubated at 28+ 1[degrees]c for 5 days. The detected fungi were carefully isolated into pure cultures on Sabouraud Dextrose Agar in plates and slants. The plates and slants were grown for seven days in an incubator preset at 28[degrees]C. Fugal isolates from plates were prepared into mounts on microscopic slides. These were prepared into mounts on microscopic slides. These were examined under the microscope for comparison of fungal morphology with descriptions given by Samson and Reenen-Hoekstra [12]

Pathogenicity of Isolated Fungi:

Three healthy fruits from each sample were surface sterilized with 90% ethanol, and incisions were made on them using a sterile 4mm cork borer; similar sterile cork-borer was used to cut pellets of agar containing the cultures of fungal mycelia of the isolates. These fungi were then inoculated into the hole created on the healthy fruits in a laminar flour chamber. The inoculate wound was sealed with petroleum jelly. Two controls with incision but not inoculated were established

The inoculated fruits and the controls were placed in a clean polyethene bag (one fruit per bag) each moistened with-wet balls of absorbent cotton wool to create a humid environment and incubated at 28[degrees]c for 5 days. After 72 hours, the inoculated fruits were observed for symptom development. The causal agents were re-isolated from the infected fruits and compared with the original isolates.

Result:

Seven fungal species, Aspergillus Sp, Rhizopus Sp, Candida Sp, Fusarium Sp, Phytophora Sp and Mucor Sp. were isolated from a total of twelve fruits. Aspergillus flavus was isolated from Carica papaya and, Ananas comosus, while Aspergillus niger was isolated from Citrus sinensis), Rhizopus Sp was obtained from Carica papaya and Lycopersicon esculentum, Candida sp was isolated from Citrus sinensis and Lycopersicon esculentum while Fusarium Sp, and Mucor Sp were isolated from Lycopersicon esculentum and Phytophthora Sp from Ananas comosus. (Table 1)

The frequency of occurrence shows that Aspergillus sp had the highest frequency occurring in five out of the 12 fruits tested (Table 2). Pathogenicity tests revealed that the isolated organisms were pathogenic. They were able to produce the same spoilage signs in the healthy fruits into which they were re- inoculated. (Table 3)

Discussion:

The fungi found associated with the spoilage of Pawpaw were Aspergillus flavus sp. and Rhizopus stolonifer sp. Baiyewu et al [2] reported that Aspergillus sp. and Rhizopus Sp, which is the same genus with those isolated from pawpaw in this study, as responsible for the soft rots of Pawpaw in southwestern Nigeria. Aspergillus niger and Candida tropicalis. were found associated with deterioration of orange; this is in line with the work of Niji et al [7] who reported that Aspergillus Sp. is the predominant organism associated with the spoilage of orange. The isolation of Phytophthora Sp., Aspergillus flavus and Candida tropicalis from pineapple is in line with the work of Efiuvwevwere [4] who reported that Aspergillus sp. and Candida Sp. is responsible for rotting of pineapple. The isolation of Fusarium oxysporum, Rhizopus stolonifer and Mucor Sp. from tomato confirmed the studies of Chuku et.al [3], Purse Glove [11], and Efiuvwerwere [4] who reported that Fusarium Sp, and Rhizopus stolonifer is responsible for the soft rot of tomato. Onyia et.al. [9] also reported that Fusarium monilifome, Aspergillus niger and Rhizopus stolonifer were isolated from rotten tomato fruits.

The prevalence of fungi as the spoilage organism of fruits and vegetables is due to a wide range of factors which are encountered at each stage of handling from pre-harvest to consumption and is related to the physiological and physical conditions of the produce as well as the extrinsic parameters to which they are subjected [4]. Damage inflicted on produce at the time of harvest is a major cause of infection since most of the spoilage microorganisms invade the produce through such damage tissues; similarly, the extent of deterioration is influenced by the depth of the wound. Furthermore, the incidence of infection is worsened by poor sanitary practices such as cross-contamination, contact infection during the transportation of produce [4].

Colonization of fruits and vegetables by the invading microorganism is a critical phase in the microbial spoilage of produce. The colonization process involves the ability of the microorganism to establish itself within the produce. This is initiated when the microorganism (following adhesion and release of enzyme) degrade certain specific cell wall polymers such as protopectin, the cementing substance of the produce. The magnitude of the symptoms of the induced disease is a reflection of the extent of colonization [3]. Whereas both fruits and vegetables are highly susceptible to microbial spoilage, there is a variation in the susceptibility which is due largely to the differential chemical composition such as pH and moisture contents Thus, the lower pH and moisture contents of the fruits makes them more prone to fungal spoilage Efiuvwevwere, [4] also reported that high moisture and relative humidity led to greater fungal growth in agricultural produce and thus low storability of fruits and vegetables.

Conclusion:

Fruits and vegetables are very important and have high dietary and nutritional qualities. Pawpaw fruit can be freshly eaten or cooked. It can also be used in the preparation of jellies, juice and jams. It has great application in the preparation of fruit salad and desserts orange juice is made from fresh healthy oranges. Sweet orange oil is a by-product of the juice industry produced by pressing the peal. Pineapple can be used to prepare juice and fruit salad. Tomatoes are eaten raw or cooked. Large quantities of tomatoes are used to cook soup, juice, sauce, puree, paste and powder, seeds contain 24% oil and this is extracted from the pulp and residues of the canning industry [3].

The high prevalence of some fungi demand that appropriate control measures against infection, should be employed if farmers expect good performance of their produce. Adequate microbiological knowledge and handling practices of these produce would therefore help minimize wastes due to deterioration and unacceptability. The high moisture content of fruits and vegetables will be a serious limiting factor in their preservation. The fruits used in this study are not produced in the metropolis they are transported to the city from distant places in locally woven baskets and sacks under weather conditions that encourage the incubation of these contaminating microorganisms. It is therefore important that both the farmer who harvests the fruits into bags for transportation, the marketers and consumers take necessary precaution in preventing contamination and also try to create an environment that will not encourage the growth or multiplication of microorganisms. This will help in preventing the consumption of contaminated fruits thereby reducing the risk of poisoning by aflatoxin and other mycotoxins which are produced by these fungi that have been isolated in this study.

References

[1.] Amusa, N.A., I.A. Kehinde and O.A. Ashaye, 2002. Bio-deterioration of Breadfruit (Artocrarpus communis) in storage and its effects on the Nutrient Composition. African Journal of Biotechnology, 1(2): 57-60.

[2.] Baiyewu, R.A., N.A. Amusa, O.A. Ayoola, and O.O. Babalola, 2007. Survey of the post harvest Diseases and Aflatoxin Contamination of Marketed Pawpaw Fruit (carica papaya) in south western Nigeria. African journal of Agricultural Research, 2(4): 178-181.

[3.] Chuku, E.C., D.N. Ogbonna, B.A. Onuegbu and M.T.V. Adeleke, 2008. Comparative Studies on the Fungi and Bio-Chemical Characteristics of Snake Gaurd (Trichosanthes curcumerina linn) and Tomato (Lycopersicon esculentus mill) in Rivers state, Nigeria. Journal of Applied Sciences, 8(1): 168-172.

[4.] Effiuvwevwere, B.J.O., 2000. Microbial Spoilage Agents of Tropical and Assorted fruits and Vegetables (An Illustrated References Book). Paragraphics publishing company, Port Harcourt. pp: 1-39.

[5.] Gupta, A.K., V.N. Parthak, 1986. Survey of fruit Market for Papaya fruit Rot by Fungi pathogens; Indian J. Mycol., 16: 152-154.

[6.] Ihekoronye, A.I. and P.O. Ngoddy, 1985. Integrated Food Science and Technology for the Tropics. Mc Millan Publishers, London, pp: 258Nijis, Dee Van H.P. Egmond, F.M. Rombouts, and S.H.W. Notermans, 1997. Identification of Hazardous Fusarium Secondary Metabolites occurring in Food Raw Materials. Journal of Food Safety, 17: 161-191.

[7.] Nijis, Dee Van H.P. Egmond, F.M. Rombouts, and S.H.W. Notermans, 1997. Identification of Hazardous Fusarium Secondary Metabolites occurring in Food Raw Materials. Journal of Food Safety, 17: 161-191.

[8.] Onuegbu, B.A., 2002. Fundamentals of Crop Protection, ASCEU, RSUST, Port Harcourt, pp: 204-208.

[9.] Onyia, V.N., C.O. Mbuka, G.O. Ihejirika, O.P. Obilor, C.I. Duruigbo and E.C. Onweremadu, 2005. Studies on the Performance and Incidence of Fusarium wilt of Tomatoes under different colours of plastic mulch. Nig. Soc. Plant proc. 32nd Ann. Conf. Book of Abstract, pp: 23-25.

[10.] Paul Singleton and Sainsbury Diana, 1981. Dictionary of Microbiology. John Wiley and Son's Publication, New York.

[11.] Purseglove, W., 1977. Tropical Crops Dicotyledons vol. 1 and 2 ELBS, pp: 137-533.

[12.] Robert. A., Samson and S. Ellen., Van Reenen-Hoekstra, 1988. Introduction to food borne fungi 3rd edition. CBS.

[13.] Snowdon, A.L., 1988. A Review of the nature and causes of Post harvest Deterioration in Fruits and vegetables, with special References to those in International Trade. Biodeterioration, 7: 585-602.

Corresponding Author:

Akinmusire, O.O., Department of Microbiology University of Maiduguri, Borno Nigeria E-mail: bolayanju1@yahoo.com

Akinmusire, O.O.

Department of Microbiology University of Maiduguri, Borno Nigeria

Akinmusire, O.O.: Fungal Species Associated with the Spoilage of Some Edible Fruits in Maiduguri Northern Eastern Nigeria
Table 1: Identification of fungal isolates from fruit samples showing
different spoilage patterns.

Fruit sample       Spoilage                   Macroscopic examination

Carica papaya      Sunken large depression    Colony white then
                                              light yellow-green,
                                              becoming dark
                                              yellow-green.

Carica papaya      Water soaked wrinkled      Whitish becoming
                   appearance with            brown black with
                   depression                 age

Ananas comosus     Sunken large depression    Colony white then
                                              light yellow-green,
                                              becoming dark
                                              yellow-green.

Ananas comosus     White deposit, fruit       Creamish white
                   become spongy with         colonies, opaque,
                   gas production             smooth, convex,
                                              entire and butyrous

Ananas comosus     Whitish foamy-like         Bluish-brown colour
                   growth with sunken         appearance, a long
                   depression                 branched thread-like
                                              filament of cell
                                              called hyphae

Citrus sinensis    Dark brown discoloration   Black colonies with
                   sunken spots Fruits        white edges
                   become spongy with gas
                   production

Citrus sinensis    Fruit becoming spongy      Creamish white
                   with gas production        colonies, opaque,
                   Sunken spots               smooth, convex,
                                              entire and butyrous

Lycopersicon       Water soaked wrinkled      Whitish becoming
esculentum         appearance and             brown black with
                   depression                 age

Lycopersicon       Water soaked wrinkled      Colony gray becoming
esculentum         appearance and             Brownish-gray with
                   depression                 age.

Lycopersicon       Whitish-pink               Colonies are
esculentum         mycelial growth            whitish-pick with
                                              a purple tinge
                                              mycelium extensive
                                              and cottony in
                                              culture

Fruit sample       Microscopic examination    Organism

Carica papaya      Conidial heads are         Aspergillius flavus
                   radiate, later splitting
                   into several loose
                   columns. Conidiophores
                   hyaline, coarsely
                   roughened vesicle is
                   globose and flask-shaped
                   phialides that produced
                   chains of rough conidia
                   are borne directly
                   on the vesicle.

Carica papaya      Non septate mycelia        Rhizopus stolonifer
                   Sporangios pores are
                   directly opposite
                   the branched rhizoids.
                   Sporangia are
                   subglobose.
                   sporangiospores are
                   ovoid in shape and
                   columella are subglbose.

Ananas comosus     Conidial heads are         Aspergillius flavus
                   radiate, later
                   splitting into several
                   loose columns.
                   Conidiophores hyaline,
                   coarsely roughened
                   vesicle is globose and
                   flask-shaped phialides
                   that produced chains of
                   rough conidia are borne
                   directly on the vesicle.

Ananas comosus     Budding, spherical to      cells, forming
                   elongate cells, forming    pseudomyceliu
                   pseudomyceliu

Ananas comosus     Zoospore bearing           Phytophthora sp
                   flagellate are seen
                   which  confirmed
                   homogenous sporangia
                   mortility on the
                   zoospore abundant

Citrus sinensis    Conidial heads are         Aspergillus niger
                   large, globose and dark
                   brown, becoming radiat
                   and splitting into
                   several columns with
                   age. Conidiophore stipes
                   is smooth walled.
                   Conidial heads ar
                   biseriate, and phialides
                   are borne on metula.
                   Conidia are globose
                   and rough walled.

Citrus sinensis    Budding, spherical to      Candida tropicalis
                   elongate cells, forming
                   pseudomycelium

Lycopersicon       Non septate mycelia        Rhizopus stolonifer
esculentum         Sporangiospores are
                   directly opposite the
                   branched rhizoids.
                   Sporangia are
                   subglobose.
                   sporangiospores are
                   ovoid in shape and
                   columella are
                   subglobose.

Lycopersicon       Non speptate mycelia       Mucor Sp
esculentum         with branching
                   sporangiophores;
                   columella pyriform,
                   ellipsoidal, pointed
                   conical

Lycopersicon       Micro-conidia, ovoid to    Fusarium
esculentum         ellipsoidal in shape are   oxysporum
                   borne on simple
                   phialides. Macro conidia
                   are borne on phialides
                   on branched
                   conidiospores. Septate
                   fusiform, slightly
                   curved and pointed at
                   both ends

Table 2: Frequency of occurrence of each isolate in fruit samples.

Fruit Sample      Total number      Fungal species    Percentage
                  of samples                          frequency

Carica papaya     2                 Aspergillius      66.7%
                                    flavus
                  1                 Rhizopus          33.3%
                                    stolonifer

Ananas comosus    1                 Candida           33.3%
                                    tropicalis
                  1                 Aspergillius      33.3%
                                    flavus
                  1                 Phytophthora sp   33.3%
                                    & Candida
                                    tropicalis

Citrus sinensis   1                 Candida           33.3%
                                    tropicalis
                                    Aspergillus       66.7%
                                    niger

Lycopersicon      1                 Fusarium          33.3%
esculentum                          oxysporum
                  1                 Mucor Sp &        33.3%
                                    Rhizopus
                                    stolonifer
                  1                 Fusarium          33.3%
                                    oxysporum &
                                    Mucor Sp

Table 3: Pathogenicity test result

Fungal species         Fruit inoculated       Spoilage pattern
                                              produced

Aspergillus flavus     Carica papaya          Sunken spots
                       Ananas comosus         Sunken depression

Aspergillus niger      Citrus sinensis),      Dark brown
                                              discoloration sunken
                                              spots

Rhizopus stolonifer    Lycopersicon           Water soaked
                       esculentum)            wrinkled appearance
                                              with depression
                       Carica papaya          Water soaked
                                              wrinkled appearance
                                              with depression

Mucor Sp               Lycopersicon           Water soaked
                       esculentum             appearance with
                                              whitish depression

Candida tropicalis     Citrus sinensis        Fruit is spongy with
                                              gas production.
                       Ananas comosus         White deposit, fruit
                                              become spongy with
                                              gas production
Fusarium oxysporum     Lycopersicon           Whitish-pink mycelia
Phytophthora sp        esculentum             growth
                       Ananas comosus 1       Whitish foamy-like
                                              growth with sunken
                                              depression.
COPYRIGHT 2011 American-Eurasian Network for Scientific Information
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2011 Gale, Cengage Learning. All rights reserved.

Article Details
Printer friendly Cite/link Email Feedback
Author:Akinmusire, O.O.
Publication:Advances in Environmental Biology
Article Type:Report
Geographic Code:6NIGR
Date:Jan 1, 2011
Words:2845
Previous Article:Response of maize genotypes to changes in chlorophyll content at presence of two types humic substances.
Next Article:Harvest index and its associated characters in winter wheat genotypes against terminal drought at presence of a peat derived humic fertilizer.
Topics:

Terms of use | Privacy policy | Copyright © 2021 Farlex, Inc. | Feedback | For webmasters |