Nine microorganisms were isolated from four varieties of Dioscorea rotundata (gbongu, ogoja, Amula, Hembamkwase); four bacteria, Erwinia carotovora, Pseudomonas aeruginosa, Serratia marcescens, Klebsiella oxytoca and five fungi, Rhizopus stolonifera, Aspergillus niger, Aspergillus flavus, Fusarium oxysporum, Penicillium marneffei, from five local government areas of Benue State (Vandeikya, Ukum, Katsina Ala, Guma and Logo). Pathogenicity test on the isolates confirmed them to be the cause of rot. The nine plants extract ( Ceiba pentandra, Jatropha tanjorensis, Azadirachta indica, Moringa oleifera, Carica papaya, Mangifera indica, Daniella oliveri, Terminalia catapa and Passiflora edulis) synergistically added inhibited all the four bacteria isolates completely. The five fungi were inhibited by 60% (c) - 80% (b); Rhizopus stolonifera, Aspergillus flavus, Fusarium oxysporum; and Aspergillus niger, Penicillium marneffei, respectively.
Africa is the highest producer of yam in the world. West Africa is the largest producer of yam in Africa and Nigeria, the highest in West Africa [
Pesticides and plant extracts can be used to prevent or at least reduce postharvest losses in yam [
Plant extracts are known to inhibit partially or completely only selected organisms [
The aim of this work is to use plants which are known to be food to mankind and are at the same time used for medicinal purposes for humans and livestock, for preservation of food and indeed control of postharvest losses. It is hoped that with careful blending and changes in concentration of extracts applied to the organisms, complete or higher percentage of inhibition of all microorganisms may be achieved. This study reports our findings on synergistic effects using nine plants (Ceiba pentandra, Jatropha tanjorensis, Azadarichta indica, Moringa oleifera, Carica papaya, Mangifera indica, Daniella oliveri, Terminalia catapa and Passiflora edulis) and nine microorganisms; four bacteria (Erwinia carotovora, Pseudomonas aeruginosa, Serratia marcescens, Klebsiella oxytoca) and five fungi (Rhizopus stolonifera, Aspergillus niger, Aspergillus flavus, fusarium oxysporum, Penicillium marneffei).
Sixty cut or bruised tubers and sixty healthy tubers of Discorea rotundata; 6 tubers of each of the varaieties (Gbongu, Ogoja, Amula and Hembamkwase) were purchased from farmers in Vandeikya, Ukum, Katsina Ala, Guma and Logo Local government area of Benue State, amounting to 15 tubers of each variety per local government. The samples were labeled, dated, and packaged in cellophane bags at collection sites. These were transported to the Microbiology Laboratory of Benue State University, Makurdi; where they were kept and some were analyzed on appearance of visible sign of rot, while others were used for pathogenicity test.
Plant leaves of Ceiba pentandra, Jatropha tanjorensis, Azadarichta indica, Moringa Oleifera, Carica papaya, Mangifera indica, Daniella oliveri, Terminalia catapa and Passiflora edulis used for the plants extract were collected along Gboko road, Makurdi.
Isolation of bacteria and fungi from rotten yam tubers was carried out by the methods of [
The methods of [
Nutrient Agar (HIMEDIA, India) for bacteria isolation and potato dextrose agar (Micro Master, India) for fungi isolation were prepared according to manufactures directions respectively. Biochemical test media and reagent were also prepared according to standard methods [
The method of [
The distinct colonies of organisms were sub-cultured severally until a single uniform growth was achieved. The bacteria were identified by the method of [
The methods of [
The methods of the Tiv traditional health care in Benue, Nigeria, using plant extracts (unpublished work) and [
The method of [
The methods of [
Four bacteria species (Erwinia carotovora, Pseudomonas aeruginosa, Serratia marcescens and Klebsiella oxytoca) and five fungi species (Rhizopus stolonifera, Aspergillus niger, Aspergillus flavus, Fusarium oxysporum and Penicillium marneffei were isolated from the rotten yam tubers (
Pathogenicity test on the isolated microorganisms showed tissue rot, damage intensity and different pigment production by different microorganisms. Re- isolation of the seeded organisms from the rotten tissues confirms them to be responsible for the rot (
Synergistic effect of nine plants extract mix on the isolates reveals that 1.0 mL addition of extracts in the culture media was able to inhibit mildly (e) the growth
Bacteria | Fungi |
---|---|
Erwinia carotovora | Rhizopus stolonifera |
Pseudomonas aeruginosa | Aspergillus niger |
Serratia marcecens | Aspergillus flavus |
Klebsiella oxytoca | Fusarium oxysporum |
Penicillium marneffei |
Microorganisms | Yam Varieties | |||
Gbongu Width depth | Ogoja Width depth | Amula Width depth | Hembamkwase Width depth | |
Erwinia carotovora | 1.2 2.3 | 1.2 2.9 | 1.0 4.8 | 1.8 3.2 |
Psendomona aeruginosa | 2.1 3.0 | 1.4 2.9 | 1.2 2.4 | 1.5 3.0 |
Serratia marcescens | 1.2 3.1 | 1.2 3.0 | 1.1 2.2 | 1.2 3.2 |
Klebsiella oxytoca | 1.0 1.8 | 1.5 2.8 | 1.4 3.6 | 1.6 2.4 |
Rhizopus stolonifera | 2.3 4.1 | 1.0 2.6 | 1.0 2.6 | 1.0 2.8 |
Aspergillus niger | 1.7 3.0 | 2.0 3.3 | 2.2 3.2 | 1.4 3.0 |
Aspergillus flavus | 1.8 2.6 | 2.1 3.2 | 1.8 2.4 | 2.3 3.2 |
Fusarium oxysporum | 2.1 2.2 | 1.2 2.4 | 1.6 3.0 | 1.0 2.0 |
Penicillium maneffei | 1.2 2.0 | 1.5 2.2 | 1.1 2.0 | 1.6 2.4 |
All bacteria | 2.1 3.6 | 2.2 3.4 | 1.6 3.2 | 2.0 3.4 |
All fungi | 2.0 3.3 | 2.7 3.3 | 1.8 2.2 | 2.2 3.6 |
All bacteria and all fungi | 3.1 3.5 | 2.3 3.6 | 2.4 4.2 | 3.6 4.2 |
of only two bacteria (Erwinia carotovora and Klebsiella oxytoca) without affecting the other bacteria or fungi; 2.0 mL incorporation of the extract was able to inhibit all the four bacteria isolates completely, the fungi isolates were still not inhibited. Addition of 3.0 mL of extract showed mild inhibition (e) for Aspergillus niger and Penicillium marneffei without affecting the other three fungi; 4.0 mL incorporation of the extract showed mild inhibition (e) of Rhizopus stolonifera and Fusarium oxytoca, moderate inhibition (d) of Aspergillius niger, Penicillium marneffei and Aspergillus flavus. There was marked increase in the inhibition with the addition of 5.0 mL of the extract, showing good inhibition (c) for Rhizopus stolonifera, Aspergillus flavus and Fusarium oxysporum; and high inhibition (b) for Aspergillus niger and Penicillium marneffei (
The study confirms the isolate as microorganisms responsible for microbial yam tuber losses in most part of Benue State, Nigeria as they were previously isolated [
Pathogenicity test confirms that the isolates were responsible for the yam tuber rot as earlier reported [
The complete inhibition of the four bacteria (Erwinia carotovora, Pseudomonas aeruginosa, Serratia marcescens and Klebsiella oxytoca) by the synergistic plants extract (Ceiba pentandra, Jatropha tanjorensis, Azadarichta indica, Moringa Oleifera, Carica papaya, Mangifera indica, Daniella oliveri, Terminalia catapa and Passiflora edulis) has not yet been reported by other workers, using
Microorganism | Extract volume applied | ||||
---|---|---|---|---|---|
1 ml | 2 ml | 3 ml | 4 ml | 5 ml | |
Bacteria | |||||
Erwinia carotovora | +e | +++++a | NA | NA | NA |
Pseudomonas aeruginosa | -f | +++++a | NA | NA | NA |
Serratia marcescens | -f | +++++a | NA | NA | NA |
Klebsiella oxytoca | + e | +++++a | NA | NA | NA |
Fungi | |||||
Rhizopus stolonifera | −f | −f | −f | +e | +++c |
Aspergillus niger | −f | −f | +e | ++d | ++++b |
Aspergillus flavus | −f | −f | −f | ++d | +++c |
Fusarium oxysporum | −f | −f | −f | +e | +++c |
Penicillium marneffei | −f | −f | +e | ++d | ++++b |
synergistic or single plant extracts. Single bacteria have been inhibited by synergistic plant extracts as well as single plant extract [
The plants in the study are all edible by man and livestock without any recorded danger on health. There is need to research further on the use of synergistic plants extract for their application on tubers and perhaps crops in general to prevent microbial rot and poison for shelf life elongation and the economic benefits that may follow.
Our gratitude goes to the management of Benue State University Makurdi for the facilities and finances made available to us to carry out this research, the famers in the various local governments where the samples were obtained. We appreciate the assistance of the staff of Biology and Chemistry Departments of Benue State University.
Shiriki, D., Obochi, G.O., Eke, M.O. and Shambe, T. (2017) Postharvest Loss Control: Synergistic Plants Extract Inhibition of Ten Microbial Yam Rot Organisms. Food and Nutrition Sci- ences, 8, 725-732. https://doi.org/10.4236/fns.2017.87051