Moroccan Journal of Biology 07-2008/N 4-5 Isolation and characterisation of yeast strains for the olive fly Bactrocera oleae biological control
Ahmed El Haidani1, Malika Chakri1, Mohammed Mostakim1, Mohammed El Mzibri2,
Jalila. Boudouma1, Mhammed El Hassouni3, Abdelatif Haggoud1, Mohamed Housaini
Iraqui1 Abdellah Houari1 and Saad Koraichi Ibnsouda1*,
1Laboratoire de Biotechnologie Microbienne, Université Sidi Mohammed Ben Abdellah, Faculté des Sciences et Techniques de Fès, Route d’Immouzer, BP 2202, Fès, MAROC. Corresponding author: 2Unité de Biologie et Recherche Médicale, Centre National de l'Energie, des Sciences et Techniques Nucléaires (CNESTEN), BP 1382 RP. 10001 Rabat, MAROC. 3Laboratoire de Biotechnologie, Université Sidi Mohammed Ben Abdellah, Faculté des Sciences Dhar El Abstract Bactrocera oleae (Diptera: Tephritidae) is one of the major pests of the olive fruits all around the Mediterranean basin. Our laboratory is interested in developing microbial strategies to fight this insect. During B. oleae’s breeding, certain pupas were unnable to accomplish their development cycle. These pupas were used to isolate pathogenic yeast strains against B. oleae. Two strains were shown to be particularly interesting. Their actions during different stages of B. oleae’s development were determined. The two strains were identified as Pichia guilliermondii and Debaryomyces hansenii according to both conventional and molecular methodologies. Key words: Bactrocera oleae (Diptera: Tephritidae), Bio-control, Debaryomyces hansenii, Pichia guilliermondii, Yeast strains. Introduction
The olive fruit’s fly Bactrocera oleae
usually spread by aircraft over vast areas,
(Diptera: Tephritidae) is one of the major
Mediterranean basin. In fact, the damages
caused by this insect are very important
become black and fall before maturation;
insecticide residues in the olive oil mainly
and the quality of oil is degraded (high
caused by high concentrations of lipophilic
degree of acidity, low organoleptic quality
and unpleasant flavour). This leads to the
decrease of the commercial values of the
improve B. oleae control including the male
olives and their oil. Furthermore, it is
sterilization technique (Tzanakakis, 1967)
important to note that the international
and the use of pheromone baits (Haniotakis
regulations tolerate less than 2 % of B.et al. 1987, Broumas et al. 1990). Natural
The control of B. oleae population is
method of control is based on the use of
killing activity have been developed in bio-
conventional pesticides. In fact, control of phytopathogenic micro-applications of some organophosphate
organisms and pathogens in agriculture and
mainly used to kill B. oleae adults.
A. El Haidani et al. / Moroccan J. Biol. 4-5 (2008) 1-8
Janisiewcz & Korsten 2002). There exists a
currently used for insect control (Lacey et
limited number of pathogenic yeast species
and they generally belong to Candida,
reported to suffer high infection levels
Saccharomyces and caused by fungi. Entomophthora muscaeMalassezia genera. These yeasts are known
infects several species (Delia antigua, Delia
as "opportunists" i.e. that they are frequent
coarctata, Chamaepsila rosae) and flies
in the environment but do not parasitize any
associated with animal production (Musca
host unless the latter presents intrinsic or
penetration, adhesion and multiplication in vivo (Drouhet & Dupont, 1979). The yeast
killer toxins (mycocines) are suspected to
virulence of some fungi against B. oleae
play a significant ecological role like a form
adults, in particular Beauveria bassiana,
Beauveria brongniartii and other species
isolated from B. oleae pupae and Sesamia
occasional high infection levels in insect
demonstrated that the B. oleae fly is
populations despite the fact that during the
sensitive to different tested isolates of toxic
last years, several species have been and
still are used and engineered as biocontrol
Sesamia nonagrioides was the most virulent
agents (Tanada & Kaya 1993, Hajek & St.
to B. oleae. Its high toxicity was related to
Leger 1994). Strains such as Beauveria bassiana (Balsamo) Vuillemin,Metarhizium anisopliae (Metschnikoff),
isolate pathogenic yeast strains from dead
Verticillium lecanii (Zimmermen) and
pupas and evaluate their toxicities against
Paecilomyces fumosoroseus (Wize) are
B. oleae adults in order to use them in different bio-control strategies. Materials and methods Yeast culture medium
then washed three times in sterile distilled
water (Cavados et al., 2001). The treated
Rij (1987) was used for yeast’s isolation
volume of 100 µl of various dilutions (10-1
medium containing three antibiotics (see
µg/ml) and Tetracyclin (30 µg/ml) to avoid
preserved at 4°C for frequent use and at -
Yeast isolated from dead pupas Identification of yeast strains
during the breeding of B. oleae in our
amplification of the ribosomal RNA 5.8 S
organisms contaminating the surfaces, the
3') primers allow the amplification of 5.8 S
A. El Haidani et al. / Moroccan J. Biol. 4-5 (2008) 1-8
program, version 5, May 2000” (Barnett et
amplification reaction was performed in a
al., 2000). Briefly, the physiological tests
final volume of 50 µl containing 50 pmol
of each primer (ITS-1 and ITS-4), 200 µM
polymerase buffer. The mixture was first
temperature tolerance tests, cyclohexemide
denatured at 94°C for 7 min. Then, thirty-
vegetative reproduction and formation of
extension at 72°C for 90 s. At the end of
the last cycle, the mixture was incubated at
72°C for 7 min. For each reaction, a negative control missing DNA template,
Test of yeast strains pathogenesis on B. oleae development
Efficient amplification was confirmed by
gel electrophoresis on 1.5% agarose gel.
yeast strain tested was spread over an YPG
medium and incubated at 30°C for 48 h. A
carpet of each strain was obtained in each
dish. B. oleae L3 larvae recovered from
reactions, then the sequence reaction for
medium (Tsitsipis, 1977) during 24 hours
thermocycler. The sequencing reaction was
containing the tested strain and incubated
containing 20 pmol of each primer (ITS-1
at 25°C. The development of these larvas
or IST-4), 3 µl of Big Dye (version 1.1)
was followed until their transformation to
and 2 µl of purified PCR product. Twenty
five cycles were performed: denaturation at
96°C for 10 s, primer annealing at 55°C for
10 s, and extension at 60°C for 4 min. In
B. oleae adults used in this work were
order to eliminate the excess of labelled
obtained from our laboratory at 24 °C with
Control Strain
study was isolated in our laboratory from
larvae of B. oleae. This strain identified as
(ABI Prism 310 Genetic Analyser, Applied
Candida diddensiae (Chakri et al., 2007)
Biosystem) and data analysis was done by
was used as control so as to estimate the
rate of pathogenic capacity of the tested
Nucleotide sequences
the molecular procedure, the conventional
Barnett et al. 2000). The results analysis
was done with the “Yeast identification PC
A. El Haidani et al. / Moroccan J. Biol. 4-5 (2008) 1-8
Table 1. Sequenced product and registered number in GenBank. Sequenced product registered number in Yeast Strain Results Isolation of yeast strains Identification of yeast strains
During B. oleae breeding, some dead
used to isolate yeast strains that would be
Several strains were isolated on YPG agar
containing three antibiotics (Ampicilline,
sequences are reported in figure 1. These
tetracycline and kanamycine). Eight strains
program (Table 3). For strain YS1, the 581 nucleotides sequenced show 98% of
Test of yeast strains pathogenesis on B. oleae development
correspond to two species Candida B. oleae were followed up on a medium
psychrophila and Debaryomyces hansenii.
Furthermore, the 540 nucleotides sequence
pupae and the percentage of lethality were
recorded. Among the eight tested strains,
Pichia guilliermondii (Table 3 and
important rate of lethality against B. oleae.
The results obtained for these strains are
were subject to conventional identification
strong lethality of B. oleae. This mortality
according to Barnett et al. (2000). This
larval stage (85.2%), whereas the mortality
between Debaryomyces hansenii and
at the pupa stage was only 10.1%. In the
Candida psychrophila. Thus, strains YS1
presence of SY1 strain, the larval viability
and YS2 were identified as Debaryomyces hansenii and Pichia guilliermondii with a
Table 2. Test of yeast strains pathogenesis on B. oleae development (Page 9; lane 15). Larval development and pupation of B. oleae were followed up on a medium containing the tested yeast strain. In parallel, the number of dead larvae and pupae and the percentage of lethality were montred. SY2 showed a strong lethality of B. Oleae ( 95 %) and acted mainly at the larval stage (85.2%), whereas the mortality at the pupa stage was only 10.1%. For SY1 strain, the larval viability was very weak (19.4). Strain Total Dead pupae total lethality Emerged adults (larvae and pupas) (viability) Candida diddensiae (control)
A. El Haidani et al. / Moroccan J. Biol. 4-5 (2008) 1-8
Table 3. Sequence analysis of RNA 5,8S PCR products amplified from YS1 and YS2 yeast strains (Page 10, lane 1 and 6). The sequences of YS1 and YS2 strains are reported. These sequences were compared with available DNA sequence database using BLAST program. For strain YS1, the 581 nucleotides sequenced show 98% of homology with the ITS DNA sequences found in the GeneBank database that correspond to two species Candida psychrophila and Debaryomyces hansenii. The 540 nucleotides sequence of strain YS2 show 98% of homology with the ITS DNA sequences found in the GeneBank database that correspond to Pichia guilliermondii. Sequenced Percentage of Reference homology
1 TTGTTTGTTATATTGTAAGGCCGAGCCTAGAATACCGAGAAATATACCATTAAACTATTC 60 61 AACGAGTTGGATAAACCTAATACATTGAGAAGTGCATATAGCACTATCCAGTACCACTCA 120 121 TGCGCAATACATTTCAAGCAAACGCCTAGTTCGACTAAGAGTATCACTCAATACCAAACC 180 181 CGAAGGTTTGAGAGAGAAATGACGCTCAAACAGGCATGCCCTTTGGAATACCAAAGGGCG 240 241 CAATGTGCGTTCAAAGATTCGATGATTCACGAAAATCTGCAATTCATATTACTTATCGCA 300 301 TTTCGCTGCGTTCTTCATCGATGCGAGAACCAAGAGATCCGTTGTTGAAAGTTTTGAAGA 360 361 TTTTTTGAATTTAATCAACAAATTGACAATTAAAATAAATAACAATTCAATATAAATATT 420 421 GAAGTTTAGTTTAGTAAACCTCTGGCCCAAACTATTTCTAGTCCAGACCAAAGCAAGAGT 480 481 TCTTGTAATAACAAAAAACACTGTGTGTAAGGGTTTTTCGCCGCGCAATTAAGCGCTGGC 540 541 AAAAAGAATACTGGAATGATCCTTCCGCAGGTTCCCCTACG 581
Figure 1a.
1 TTGTTTGGTTGTTGTAAGGCCGGGCCAACAATACCAGAAGATATCCCGCCACACCATCTC 60 61 AACGAGTGTGGATAAACCTAATACATCTGAGAGGTCGACAGCACTATCCAGTACTACCCA 120 121 TGCGCAATACTCTCTTCAAGCAAACGCCTAGTCCGACTAAGAGTATCACTCAATACCAAA 180 181 CCCGGGGGTTTGAGAGAGAAATGACGCTCAAACAGGCATGCCCTCTGGAATACCAGAGGG 240 241 CGCAATGTGCGTTCAAAGATTCGATGATTCACGAAAATCTGCAATTCATATTACTTATCG 300 301 CATTTCGCTGCGTTCTTCATCGATGCGAGAACCAAGAGATCCGTTGTTGAAAGTTTTGAA 360 361 GATTAATTCAAAATTTGACTAACTGTAAAAATAATTAAATTGTGTTTTGTTAAACCTCTG 420 421 GCCCAACCTATCTCTAGGCCAAACCAAAGCAAGAGTTCTGTATCAAAAAGACACTGTGTG 480 481 TAAGGTTTTTCGCCGCGCAGTTAAGCGCTGGCAAAAGAATACTGTAATGATCCTTCCGCA 540
Figure1b. Figure 1 (Page 9, lane 12 and 18). Nucleotide sequence of the ITS amplified fragments of the two isolated yeast strains. The two PCR products from the yeast strains YS1 and YS2 were sequenced on both strands. Figure 1a: Sequence of the 5.8S ITS region of strain YS1 Figure 1b: Sequence of the 5.8S ITS region of strain YS2 Discussion
investigations were made to evaluate the
strategies such as biocontrol can provide
additional management tools as biocontrol of B. oleae fly. Konstantopoulou supplements to other control measures for
& Mazmenos (2005) showed that several
yeast strains, especially M. hiemalis, have a
toxic effect against B. oleae adults. Two
yeast strains were isolated from death B.
from the market or fail due to new strains
oleae pupas. Conventional and molecular
identifications of these strains showed that
they belong to Pichia guilliermondii and
in isolating pathogenic yeast strains from
Debaryomyces hansenii, respectively. The
dead B. oleae pupas. Indeed, several
virulence of Pichia guilliermondii strain
A. El Haidani et al. / Moroccan J. Biol. 4-5 (2008) 1-8
was the highest - 95.3 % of lethality - when
compared to that of D. hansenii strain with
frequent yeast species to be associated with
53 % lethality only. On the other hand, P. guilliermondii strain seems to act mainly at
non-pathogenic. It has been reported that
the larval stage since only few larvae had
D. hansenii grew mainly on the cheese
contrast, D. hansenii seems to act
satisfied (Leclercq-Perlat et al., 1999;
preferentially at the pupal stage (33.6 % of
Bonaïti et al., 2004). The single case of
infection associated to D. hansenii was
reported with bone infection (Yamamoto et
reports up to date on the susceptibility of B.oleae fly to P. guilliermondii and D. hansenii yeast strains. However, Pichia
products is increasing, they only represent
guilliermondii was reported in several
about 1% of agricultural chemical sales.
works to be used for bio-control essays.
Yeast based biocontrol strategies offer an
Wisniewski et al. (1991) have isolated a P. guilliermondii strain that protects apples
from postharvest fruit rotting fungi Botrytis
demonstrated, for the first time, that P.cinerea and Penicillium expansum. Other
guilliermondii and D. hansenii have
studies have demonstrated the ability of P.guilliermondii to inhibit the growth of
specifically, the olive fruit’s fly B. Oleae.
The results obtained in this paper are of
application of these strains for bio control
Aspergillus flavus (Paster et al., 1993).
against the devastating insect B. oleae.
Arras et al. (1998) reported the use of a
Generally, the toxicity of yeast species
strain of P. guillermondii in bio-control of
resides in their produced metabolites. The
blue mould of citrus fruits. The abilities of
high toxicity of P. guilliermondii and D. Pichia anomala, Pichia guilliermondii, and
hansenii may be due to some metabolites
Saccharomyces cerevisiae to inhibit the
produced by the two species. This makes it
growth of the mould Penicillium roqueforti
necessary for further research to identify
and eventually isolate these potent active
1995). Furthermore, yeast’s application as
biocontrol agents to prevent mold decay of
fruits and vegetables has been described
biorational screening processes to identify
Richards et al. (2004) have shown that
microorganisms with biocontrol potential.
Debaryomyces hansenii and Pichia guilliermondii were antagonists to
Salmonella Poona in cantaloupe juice.
production conditions, increased emphasis
on combining biocontrol strains with each
guilliermondii and insects has already been
other and with other control methods and
documented. Different strains in the Pichiaguilliermondii clade were isolated from the
system will be of great interest for the
control of the olive fruit fly B. oleae and
(Frants & Mertvetsova 1986, Suh & Blackwell 2004).
A. El Haidani et al. / Moroccan J. Biol. 4-5 (2008) 1-8
Acknowledgments
Barji Abdelhak for their critical reading of
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Liver cancer: Descriptive epidemiology and risk factorsother than HBV and HCV infectionShu-Chun Chuang a, Carlo La Vecchia b,c, Paolo Boffetta a,*a Lifestyle, Environment and Cancer Group, International Agency for Research on Cancer, 150 cours Albert Thomas, 69008 Lyon, Franceb Department of General Epidemiology, Mario Negri Institute of Pharmacological Research, Milan, Italyc Institute of B
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