OBAFEMI, YEMISI DORCAS and Covenant University, Theses (2017) CHARACTERIZATION OF MICROORGANISMS AND EXTRACELLULAR ENZYMES ASSOCIATED WITH THE EFFECTIVENESS OF A POSTHARVEST STORAGE SYSTEM FOR TOMATO (Lycopersicon esculentum Mill.) FRUITS. Masters thesis, COVENANT UNIVERSITY.
![[img]](http://eprints.covenantuniversity.edu.ng/style/images/fileicons/application_pdf.png) |
PDF
Download (216kB) |
Abstract
Amylase (EC 3.2.1.1), Cellulase (EC 3.2.1.4), Polygalacturonase (EC 3.2.1.15) and Tannase (EC 3.1.1.20) are cellwall degrading enzymes which promote pathogenicity in microorganisms associated with spoilage of tomato fruits. Potential use of these enzymes has made it very important to optimize production process to achieve maximum yields. One hundred and eighty tomato fruits each of average weight were sorted, washed and stored in the locally made post-harvest storage system, refrigerator and at ambient temperature for a period of fourteen days. Pure bacterial and fungal isolates were screened for amylase, cellulase, polygalacturonase and tannase production based on their ability to produce clear zones of hydrolysis on the starch, carboxylmethylcellulose (CMC), pectin and tannic acid supplemented agar plates respectively. The isolates were characterized by biochemical and molecular tests and the activities of the enzymes were determined. Partial purification of the crude enzymes was carried out by ammonium sulphate precipitation. The enzymes were characterized using the parameters of temperature, pH, substrate concentration and effect of heating time. Five bacterial isolates and two fungal isolates were able to produce the cellwall degrading enzymes in tomato fruits. Isolate B5 and F2 exhibited highest amylase activity; Isolate B18 and F3 exhibited highest cellulase activity, and Isolate B5 and F3 had highest polygalacturonase activity. None of the isolate was able to produce tannase. Optimum conditions were ascertained at pH 6.0, and 5.5; temperature 30°C, and 35°C; substrate concentration of 0.25mg/ml, and 0.3mg/ml, heating for 5min and 10min for Amylase AMY F2 and AMY B5 respectively. Cellulase CMC B18 had an optimum pH of 4.5, optimum temperature of 35°C substrate concentration of 0.4mg/ml and heating for 5min while the optimum pH of 4.5, optimum temperature of 35°C, substrate concentration of 0.3mg/ml and heating for 5min was obtained for Polygalacturonase PEC B5. 16S rRNA revealed isolate code B5, B18 and B27 as Enterobacter tabaci, Enterobacter aerogenes and Citrobacter freundii respectively while the fungi isolate code F2 and F3 were identified as Aspergillus niger and Rhizopus stolonifer. This research established the efficiency of the post-harvest storage system for the storage of tomato fruits.
| Item Type: | Thesis (Masters) |
|---|---|
| Uncontrolled Keywords: | Storage system, Extracellular Enzymes, Amylase, Cellulase, Polygalacturonase, Post-Harvest |
| Subjects: | Q Science > Q Science (General) Q Science > QH Natural history > QH301 Biology |
| Divisions: | Faculty of Medicine, Health and Life Sciences > School of Biological Sciences |
| Depositing User: | Mrs Hannah Akinwumi |
| Date Deposited: | 22 Jun 2020 16:05 |
| Last Modified: | 22 Jun 2020 16:05 |
| URI: | http://eprints.covenantuniversity.edu.ng/id/eprint/13407 |
Actions (login required)
 |
View Item |
