Exploration of microbiome of medicinally important plants as biocontrol agents against Phytophthora parasitica

• Published in: Archives of microbiology Vol. 203; no. 5; pp. 2475 - 2489
• Main Authors: Iqrar, Irum, Shinwari, Zabta Khan, El-Sayed, Ashraf Sabry Abdel Fatah, Ali, Gul Shad
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-07-2021; Springer Nature B.V
• Subjects: Acetic acid; Allelochemicals; Antiinfectives and antibacterials; Antimicrobial activity; Antimicrobial agents; Arthrobacter; Assaying; Bacteria; Biochemistry; Biological activity; Biological control; Biomedical and Life Sciences; Biotechnology; Cell Biology; Crop production; Ecology; Endophytes; Enterobacter; Ethyl acetate; Fractionation; Gene sequencing; Herbal medicine; Lesions; Life Sciences; Medicinal plants; Microbial Ecology; Microbiology; Microbiomes; Original Paper; Pesticides; Phytophthora parasitica; Plant bacterial diseases; Pseudomonas; rRNA 16S; Spectroscopy; Streptomyces; Sustainable production; Tobacco; Volatiles; Medicinal plants; Bioactivity-driven fractionation; Endophytic bacteria; Biocontrol agents; HPLC; Phytophthora
• ISSN: 0302-8933; 1432-072X
• DOI: 10.1007/s00203-021-02237-2

In a preliminary plant-based microbiome study, diverse bacterial taxa were identified from different medicinal plants using 16S rRNA gene sequencing. Based on initial antimicrobial screening, eight (8) bacterial endophytes in six (6) different genera,
Streptomyces, Pseudomonas, Enterobacter, Bacillus, Arthrobacter,
and
Delftia
, from four important medicinal plants
Dodonaea viscosa, Fagonia indica, Caralluma tuberculata,
and
Calendula arvensis
were selected for further analyses
.
Antimicrobial assays revealed that
Pseudomonas taiwanensis
MOSEL-RD23 has strong anti-
Phytophthora
activity
.
Volatiles produced by
P. taiwanensis
MOSEL-RD23and
Bacillus flexus
MOSEL-MIC5 inhibited the growth of
Phytophthora parasitica
by more than 80%. Ethyl acetate extracts of
Streptomyces alboniger
MOSEL-RD3,
P. taiwanensis
MOSEL-RD23
, Enterobacter hormaechei
MOSEL-FLS1, and
Bacillus tequilensis
MOSEL-FLS3, and
Delftia lacustris
MB322 displayed high potency against
P. parasitica
. All these bacterial extracts showed strong inhibition of more than 80% inhibition in vitro against
P. parasitica
at different concentrations (4–400 µg/mL). Bacterial extracts showing strong antimicrobial activity were selected for bioactivity-driven fractionation and showed anti-
Phytophthoral
activity in multiple fractions and different peaks observed in UV–Vis spectroscopy. In the detached-leaf assay against
P. parasitica
on tobacco, 1% ethyl acetate bacterial extract of
S. alboniger
MOSEL-RD3,
P. taiwanensis
MOSEL-RD23,
E. hormaechei
MOSEL-FLS1,
B. tequilensis
MOSEL-FLS3, and
D. lacustris
MB322 reduced lesion sizes and lesion frequencies caused by
P. parasitica
by 68 to 81%. Overall,
P. taiwanensis
MOSEL-RD23 showed positive activities for all the assays. Analyzing the potential of bacterial endophytes as biological control agents can potentially lead to the formulation of broad-spectrum biopesticides for the sustainable production of crops.