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|Document Type: ||Thesis or dissertation|
|Title: ||Exploitation of Bioactive Constituents of Olive Leaves, Grape Pomace, Olive Mills Waste Water and their Application in Phytoprotection|
|Authors: ||Mavrakis, Titos Nikolaou|
|Supervisors: ||Aldred, David|
Ververidis, Filippos N.
|Issue Date: ||Oct-2009|
|Abstract: ||Pure plants extracts or/and essential oils show antifungal and antibacterial activity
against a wide range of fungi and bacteria. Recently there has been increasing interest
in the effects of natural compounds against important plant pathogens (fungi and
bacteria). Although the antimicrobial activity of oleuropein, grape pomace (GPE) and
olive mills waste water (OMWW) extracts have been studied widely, little research
has been done on the in vitro and in vivo evaluation of these extracts efficiency
against important plant diseases and postharvest treatments.
The overall objectives of this study were firstly to extract and isolate from olive leaves
(oleuropein), olive mills waste water and from grape pomace (winery by-products)
natural compounds in order to be used for in vitro and in vivo experiments.
In particular, all three natural extracts were found to restrain in vitro growth of a
series of important bacterial and fungal pathogens, such as: Botrytis cinerea, the cause
of grey mold disease, Alternaria alternata, causing leaf spots and moulds on several
plant species, Fusarium oxysporum fsp melonis, causing Fusarium wilt of melon, a
Rhizopus species (a genus causing fruit and vegetable decays), the crucifer pathogen
Colletotrichum higginsianum, causing anthracnose leaf spot disease on several
Brassica and Raphanus species and Phytophthora parasitica var. nicotianae, the
causal agent of the black shank disease of tobacco. Bacterial strains including
Clavibacter michiganensis spp. michiganensis, the cause of bacterial canker of
tomato, Ralstonia solanacearum causing bacterial wilt in solanaceous plants,
Pseudomonas syringae pv. tomato, the cause of bacterial speck on tomato and
Arabidopsis and Xanthomonas campestris pv. vesicatoria causing the bacterial spot
disease of pepper and tomato were tested. Oleuropein (semipure and pure) showed
remarkable antibacterial activity. The minimal inhibitory concentration (MIC), at least
of oleuropein was lower than 0.1%. MICs values for GPE and OMWW extract ranged
from 0.1% to 0.2%. Moreover, these natural extracts were shown to inhibit and/or
restrain spore germination of fungi in solid media, however grape pomace extract,
was sufficiently effective to inhibit spore germination and germ tube of C.
higginsianum and B. cinerea.
Furthermore in vivo antibacterial activity of pure oleuropein and OMWW extract was
assessed in greenhouse experiments, on Xanthomonas campestris pv. vesicatoria, the
cause of bacterial spot of pepper plants and Pseudomonas syringae pv. tomato, the
cause of bacterial speck of tomato plants, respectively. It seems that 0.1% pure
oleuropein (98%) and 0.1% OMWW extract had a protective effect against bacterial
spot and bacterial speck respectively, which is more obvious when oleuropein
application started before infection. Besides endophytic growth of Phytophthora
parasitica var. nicotianae, causal agent of the black shank disease of tobacco, on
tobacco leaves by measuring its radial growth inside the infected tissue, was assessed.
0.1% GPE showed the most significant inhibition in all tobacco leaves treatments.
The potential of postharvest treatment of table grapes with the grape pomace extract
(GPE) to restrain grey mould (Botrytis cinerea) disease incidence and development
was estimated. 5% GPE treatments produced the strongest inhibitory effect against B.
cinerea incidence on grape berries and the time after treatment influenced the
numbers of decayed berries.
Finally the use of pure oleuropein as antibacterial in vase solution for cut flowers
(carnation) was evaluated. Oleuropein showed strong antibacterial activity as vase
solution and carnations vase life was more than doubled by using oleuropein 200ppm
and 400ppm, compared with control (water).|
|Appears in Collections:||PhD, EngD and MSc by research theses (Cranfield Health) |
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