Tomato fruits as a Potential source of Pectinolytic Enzyme Production by Pathogenic Fungi

 H. A. Akinyele^1*, M. F. Siyanbola², C. E. Odjede², M. O. Ukhureigbe², C.I Nwokeoma², Abdulmuiz A. Akinyele^3
1Department of Microbiology, Federal University, Oye Ekiti, Ekiti State, Nigeria.
²Department of Biological Science, the Polytechnic Ibadan, Oyo State, Nigeria.
³Department of Science Laboratory Technology, Federal Polytechnic Ayede, Oyo State, Nigeria
*Corresponding Author
Received: 07 January 2023; Revised: 21 January 2023; Accepted: 01 February 2023; Published: 28 February 2023

Abstract: – Microbes are well known source for the production of extracellular enzymes and industrial important secondary metabolites. Since fruits contain pectin, hence any microorganism that will involve in their spoilage must naturally possess cell wall destroying ability. This study was aimed at isolation and characterization of pectinase producing fungi from Tomato fruits. Tomato fruits were collected from Bodija. Market, Ibadan, Nigeria. Spoilage fungi were isolated and characterized with standard techniques. Six (6) fungi were isolated from the fruits: Aspergillus niger, Penicillium nigricans, Rhizopus stolonifer, Fusarium oxysporium and Trichoderma harzanium. The fungi were screened for the pectinolytic enzyme production on solid media. Among the isolates, Aspergillus niger, Penicillium nigricans, Rhizopus stolonifer and Fusarium oxysporium were selected for pectinase production using solid state fermentation (SSF) with Orange peel. Crude enzyme production was optimized with pH, temperature, substrate concentrations and incubation period. All the isolates produced maximally at pH 7, 1.5 substrate concentration , 50 0C and 72Hr incubation except Penicillium nigricans at pH(5) and temperature of 40oC. These organisms can further be studied for their enzymes to be purified and characterized.

Keywords: pectinase; Aspergillus niger; Penicillium nigricans ; extracellular enzymes; fermentation

I. Introduction

Vegetables constitute commercially and nutritionally important indispensable food commodity. Vegetable naturally play a vital role in human nutrition by supplying the necessary growth factors such as vitamins and essential minerals in human daily diet and that can help to keep a good and normal health. Vegetables are widely distributed in nature. One of the limiting factors that influence the fruit economic value is the relatively short shelf-life period, caused by pathogen’s attack (Droby, 2006; Zhu, 2006).

Tomato (Lycopersicon esculentum) is the most important vegetable worldwide. Tomato is an annual plant, which belongs to the Solanaceae family, which includes other well-known species such as Potato, Tobacco, Pepper and Egg plants (aubergine) and can reach a height of over two meters. It is a berry fruit grown mainly in soil (Frazier and Westhoff, 2004). Tomato is essential mainly for its dietary needs and can be consumed in diverse ways. It can be cooked as vegetable, as an ingredient in many dishes and sauces; in the making of stew, fruit juices and can be eaten raw in salads (Masefield et al., 2002). Tomato is grown in gardens and irrigation schemes in West Africa. In Nigeria, most tomatoes are grown in the northern parts of the country (Erinle, 2007) and there is no record of any systematic or organized traditional storage method for vegetables and fruits. They are usually sold immediately after harvesting. They are packed in baskets, cardboard boxes, or wooden crates ready for transportation to the markets. Tomato is the most perishable vegetable during handling, transportation and storage. This is because tomato contains large amount of water that makes them susceptible to spoilage by the action of microorganisms such as fungi, bacteria and protozoans. Estimates have shown that about one third of the produce is lost before reaching the consumer (Erinle, 2007), this loss has been attributed to a number of factors which include physical (mechanical breakage, bruises), physiological and also damages caused by pathological agents (Thompson and Kelly, 2000). Market value of the tomato are mainly reduced by these factors. The spoilage of food by microorganisms should not be viewed as a sinister plot on the part of the microbes deliberately to destroy foods but as a normal function of these organisms in the total ecology of all living organisms (Watt and Merrill, 2000). It has also been estimated that 20% of all fruits and vegetables harvested for human consumption are lost through microbial spoilage causing one or more of 250 market diseases (Watt and Merrill, 2000). Spoilage of fresh tomato usually occurs during storage and transit and while waiting to be processed. Frazier and Westhoff, (2004) reported that fruits and vegetables after picking continue to respire and as a result heat is produced, this heat is known as ‘vital heat’, the amount which varies with amount of fruits and vegetables. Vegetables that respire more thereby generating most heat are those that perish/spoil most rapidly (Wheeler, 2005).

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