Content uploaded by Lamidi Yusuf
Author content
All content in this area was uploaded by Lamidi Yusuf on Mar 29, 2021
Content may be subject to copyright.
Sumerianz Journal of Agriculture and Veterinary, 2020, Vol. 3, No. 5, pp. 54-56
ISSN(e): 2617-3077, ISSN(p): 2617-3131
Website: https://www.sumerianz.com
© Sumerianz Publication
CC BY: Creative Commons Attribution License 4.0
Original Article Open Access
*Corresponding Author
54 54
Isolation and Identification of Fungi Associated With Tomato (Lycopersicon
Esculentum M.) ROT
Yusuf Lamidi *
Department of Microbiology Kogi State University, Anyigba, Kogi State, Nigeria
Agieni G. A.
Department of Microbiology Kogi State University, Anyigba, Kogi State, Nigeria
Olorunmowaju Abiodun Israel
Department of Microbiology Kogi State University, Anyigba, Kogi State, Nigeria
Abstract
Tomato (Lycopersicon esculentum) is the most popular vegetable worldwide. They have high spoilage rate because
of their high moisture content. Many pathogenic fungi are the subject of intense study because they cause disease
symptoms that have negative effect on the yield and quality of tomato fruits; they produce mycotoxins that are
detrimental to human health. Isolation and identification of fungal organisms causing rot of tomato purchased from
Anyigba main market was carried out. Sabouraud Dextrose Agar was used and four fungal species were isolated;
Aspergillus spp, Penicillium spp, Rhizopus spp and Fusarium spp. The most frequent being Aspergillus spp
(38.89%) and the lowest was Fusarium spp (5.56%). The pathogenicity test carried out implicated these organisms
in the spoilage of healthy tomato fruits. Proper handling and adequate storage facilities must therefore be employed
to prolong the shelf life of tomato fruits.
Keywords: Tomato; Fungi; Isolation; Identification; Rot; Pathogenicity test.
1. Introduction
Tomato (Lycopersicon esculentum M.) belongs to the family Solanaceae is one of the most widely grown and
extensively consumed vegetable in the world. In the Nigerian Savanna, fresh tomato is the most valuable vegetable
crop. It accounts for about 18% of the average daily consumption of vegetables in Nigeria. Tomatoes may be pear-
shaped, elongated, flattened and heart shaped. They are edible, fleshy and reddish when ripe and vary in their acid
composition, with white and yellow ones being less acidic. Tomatoes can be used as savoury or flavouring in soups
and cooked foods or can be eaten as fruits. It is used in many dishes, salads, sauces and drinks and can also be dried
and ground into pancakes [1]. Tomato fruits are mostly harvested and transported in manners that expose them to
microbial infections; they are usually harvested and transported with locally made baskets which are prone to fungal
contaminants. They are usually displayed on benches and in baskets for prospective customers in the open market
until sold, thereby exposing them to further microbial infections beside those associated with its surface and those
from adjacent infected fruits [2]. Fungi are the most important and prevalent pathogens, infecting a wide range of
fruits and causing destructive and economically important losses of the fruits during storage, transportation and
marketing [3]. These study aims at identifying fungal causing tomato rot from Anyigba Main Market, Kogi State,
Nigeria.
2. Materials and Methods
Fresh tomato samples were purchased from Anyigba main market in Kogi State, Nigeria. They were rinsed with
sterile distilled water and transported to the Microbiology laboratory, Kogi State University in sterile polythene bags
for fungal isolation. The samples were left for seven (7) days for spoilage to occur. These spoilt tomatoes were then
used for the study. One gram (1 g) of each of the spoilt tomatoes was carefully cut with the aid of a sterile scalpel,
ten-fold serial dilutions of the sample were thereafter carried out in serially marked test tubes for a serial dilution
process and then removed and an appropriate dilution factor was obtained from the isolation of distinct colonies and
enriched in sterile Sabouraud dextrose agar media for seventy two (72) hours. The 10-3 diluent was used for
incubation. Following sample preparation, an aliquot (1ml) from the tube with the highest dilution factor (10-3) was
inoculated onto the already prepared SDA media with 1ml of chloramphenicol to inhibit bacteria growth using the
spread plate method. This procedure was repeated for the subsequent plates, and was left to gel prior to incubation in
an inverted position in the incubator at 25oc ±2 for 72 hours. The colonies that developed were then counted and
enumerated in colony forming unit per ml (cfu/ml). They were later subculture before identification and
characterization. Pathogenicity test was done using the procedures of Baiyewu, et al. [2] with ten (10) healthy
tomatoes inoculated and another ten bored that serves as control. The rot diameters were measured after the seventh
day of inoculation.
Sumerianz Journal of Agriculture and Veterinary
55
3. Results and Discussion
In this investigation, the fungi Aspergillus spp, Penicillium spp, Rhizopus spp and Fusarium spp were isolated.
The precise identification of these pathogens is central of an appropriate disease management strategy. Table 1
shows that isolated Aspergillus spp is one of the major fungi responsible for the production of volatile compounds in
spoilt tomato. Baker [4], reported that they are pathogenic on tomato fruits. Akinmusire [5] reported that Rhizopus
spp were associated with tomato spoilage. Wogu and Ofuase [6] isolated Aspergillus, Penicillium, Fusarium from
spoilt tomato fruits.
Extending the shelf life of tomato fruits by controlling its ripening when it is to be transported over a long
distance can be employed. Appropriate temperature and relative humidity should be employed in tomato fruit
storage. Earlier workers have suggested 30-35oc and 50-80% relative humidity for its storage. Mechanically injured
and fungal infected fruits should not be package with healthy fruits, so as to prevent mass deterioration of tomato
fruits. Hayatu [7], reported that the high number of fungal colonies isolated on tomato could be due to physical
damage, and harvesting puncture, which could occur during harvesting and poor handling, which serve as portal of
entry for microbes. The result from Table 2 shows that all the isolates grow best aerobically as there were reductions
in their occurrence at anaerobic condition. However, Fusarium spp showed no growth anaerobically; this may be due
to the fact that Fusarium spp were obligate anaerobes. This shows that the oxygen concentration in a particular
environment also contribute to the spoilage organisms to be present in the tomato fruits.
The results of the pathogenicity tests show that these fungal isolates were capable of causing disease if the right
conditions were given. An observation worthy of note was given to a tomato species that has resistibility to fungal
spoilage; the Roma tomato. Roma tomato was able to maintain a healthy condition even when other species of the
fruit has deteriorated due to fungal spoilage (Plate 1). Morphological and microscopic characteristics were compared
with initial cultures after re-isolation and were found to be the same. The control (with bored whole and no isolate
inoculated) shows no symptoms of rot at the third day of examination. The ability of the fungal isolate to cause
disease in healthy tomato fruits was due to the fact that the pathogens are able to utilize the nutrients of the fruits as a
substrate for growth and development [8]. This was shown in Table 3 where the rot diameter of each fungi isolate
after 7 days was carefully measured.
Plate-1. Tomato fruits after the third day of fungal activity
Table-1. Occurrence Rate of Fungal Isolates
Fungal Isolates
Number of Occurrence
Rate of Occurrence (%)
Aspergillus spp.
28
38.89
Penicillium spp.
24
33.33
Rhizopus spp.
16
22.22
Fusarium spp.
4
5.56
TOTAL
72
100
Table-2. Occurrence Rate of Fungal Isolates by Spoilage Pattern
AEROBIC
ANAEROBIC
Isolates
Isolate
Frequency (%)
Isolate
Frequency (%)
Aspergillus spp.
20
41.67
8
33.33
Penicillium spp.
13
27.08
11
45.83
Rhizopus spp.
11
22.92
5
20.83
Fusarium spp.
4
8.33
0
0
TOTAL
48
100
24
99.99
Table-3. The Rot Diameter of Fungal Isolates
Sumerianz Journal of Agriculture and Veterinary
56
Isolate
Rot diameter (mm)
Aspergillus spp
20.0
Penicillium spp
8.2
Rhizopus spp
14.6
Fusarium spp
12.5
4. Conclusion
Many studies have been carried out with respect to occurrence, casual organisms, severity, losses and
pathogenicity. The present study implicated four fungal pathogens (Aspergillus, Penicillium, Rhizopus and
Fusarium) in the spoilage of tomato fruit. Tomato fruits were prone to fungal infection. This study also shows the
high occurrence of Aspergillus spp in Anyigba metropolis compare to other fungal contaminants. Control measures
must be employed by vegetative growers, marketers and consumers at the time of harvesting, transportation,
handling, storage and processing of tomato fruits to reduce these contaminants.
5. Recommendation
It is recommended that tomato fruits production should be handled with extreme care. Only recommended
chemicals are used at recommended dosage for its production and avoid the use of water flooded with untreated
sewage for irrigation. The resistant tomato species; “Roma tomato” )Plate 1) should be given more attention to detect
the genetic trait that lead to its resistibility, its productivity should also be on the increase. Individuals who prefer to
consume spoilt tomato fruits because it is very cheap should also desist as this may serve as a cheap source of
diseases too. Washing the tomato with clean water before consumption will also reduce the bacterial load.
References
[1] Onuorah, S. and Orji, M. U., 2015. "Fungi associated with the spoilage of post-harvest tomato fruits sold in
major markets in Awka, Nigeria." Universal Journal of Microbiology Research, vol. 3, pp. 11-16.
[2] Baiyewu, R. A., Amusa, N. A., Ayoola, O. A., and Babalola, O. O., 2007. "Survey of the post-harvest
disease and aflatoxin contamination of marketed pawpaw fruit (carica papaya l.) in South Western Nigeria."
Africa Journal of Agricultural Sciences, vol. 2, pp. 178-181.
[3] Sommer, N. F., Fortingae, R. J., and Edwards, D. C., 1992. "Postharvest diseases of selected commodities
(Kader A.A. Ed)." University of California Division of Natural Resources Publication, vol. 31, pp. 117-
160.
[4] Baker, S., 2006. "Aspergillus niger genomics: Past, present and into the future." Medical Mycology, vol. 44,
pp. S17-21.
[5] Akinmusire, O. O., 2006. "Fungi species associated with the spoilage of some edible fruits in maiduguri,
North Eastern Nigeria." Advances in Environmental Biology, vol. 5, pp. 157-161.
[6] Wogu, M. D. and Ofuase, O., 2014. "Microorganisms responsible for the spoilage of tomato fruits,
Lycopersicum esculentum, sold in markets in Benin City, Southern Nigeria." Scholar’s Academic Journal
of Bioscience, vol. 2, pp. 459-466.
[7] Hayatu, M., 2000. Post-harvest physiological studies of some selected members of family Solanaceae. M.
Sc Thesis (unpublished). Dept. of Biological Sciences, Bayero University, Kano., p. 25.
[8] Kator, L., Akomaye, M. U., and Okoro, J. K., 2015. "Efficacy of some botanicals in the control of fungi
causing postharvest rot of yam in katube market, Obudu, Nigeria." IOSR Journal of Pharmacy and
Biological Sciences, vol. 10, pp. 33-41.