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Abdel-Hamid MS, Fouda A, El-Ela HKA, El-Ghamry AA, Hassan SED. Plant growth-promoting properties of bacterial endophytes isolated from roots of Thymus vulgaris L. and investigate their role as biofertilizers to enhance the essential oil contents. Biomol Concepts 2021; 12:175-196. [PMID: 35041305 DOI: 10.1515/bmc-2021-0019] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 12/19/2021] [Indexed: 12/13/2022] Open
Abstract
The main objective of the current study was to improve the essential oil contents of Thymus vulgaris L. using bio-inoculation with bacterial endophytes. Therefore, out of fourteen endophytic bacterial isolates obtained from roots of T. vulgaris, five isolates were selected based on the highest nitrogen-fixation and phosphate solubilization activity and identified as: Bacillus haynesii T9r, Citrobacter farmeri T10r, Bacillus licheniformis T11r, Bacillus velezensis T12r, and Bacillus velezensis T13r. These five strains have been recorded as ammonia, hydrogen cyanide (HCN), siderophores, and indole-3-acetic acid (IAA) producers. These strains have the efficacy to fix-nitrogen by reduction of acetylene with values of 82.133±1.4-346.6±1.4 n-mole-C2H4/ml/24 h. The IAA, gibberellic acid, abscisic acid, benzyl, kinten, and ziaten production were confirmed using HPLC. Two strains of T11r and T13r showed the highest plant growth-promoting properties and were selected for bio-inoculation of T. vulgaris individually or in a consortium with different mineral fertilization doses (0, 50, 75, and 100%) under field conditions. The highest growth performance was attained with the endophytic consortium (T11r+T13r) in the presence of 100% mineral fertilization. The GC-MS analysis of thyme oil contents showed the presence of 23 various compounds with varying percentages and the thymol fraction represented the highest percentages (39.1%) in the presence of the bacterial consortium.
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Affiliation(s)
| | - Amr Fouda
- Soil Fertility and Microbiology Department, Desert Research Center, El-Mataria, Cairo, Egypt
| | - Hesham Kamal Abo El-Ela
- Soil Fertility and Microbiology Department, Desert Research Center, El-Mataria, Cairo, Egypt
| | - Abbas A El-Ghamry
- Botany and Microbiology Department, Faculty of Science, Al-Azhar University, Cairo 11884, Egypt
| | - Saad El-Din Hassan
- Botany and Microbiology Department, Faculty of Science, Al-Azhar University, Cairo 11884, Egypt
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Fouda A, Eid AM, Elsaied A, El-Belely EF, Barghoth MG, Azab E, Gobouri AA, Hassan SED. Plant Growth-Promoting Endophytic Bacterial Community Inhabiting the Leaves of Pulicaria incisa (Lam.) DC Inherent to Arid Regions. PLANTS (BASEL, SWITZERLAND) 2021; 10:E76. [PMID: 33401438 PMCID: PMC7824221 DOI: 10.3390/plants10010076] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 12/23/2020] [Accepted: 12/29/2020] [Indexed: 11/16/2022]
Abstract
In this study, 15 bacterial endophytes linked with the leaves of the native medicinal plant Pulicaria incisa were isolated and identified as Agrobacterium fabrum, Acinetobacter radioresistant, Brevibacillus brevis, Bacillus cereus, Bacillus subtilis, Paenibacillus barengoltzii, and Burkholderia cepacia. These isolates exhibited variant tolerances to salt stress and showed high efficacy in indole-3-acetic acid (IAA) production in the absence/presence of tryptophan. The maximum productivity of IAA was recorded for B. cereus BI-8 and B. subtilis BI-10 with values of 117 ± 6 and 108 ± 4.6 μg mL-1, respectively, in the presence of 5 mg mL-1 tryptophan after 10 days. These two isolates had a high potential in phosphate solubilization and ammonia production, and they showed enzymatic activities for amylase, protease, xylanase, cellulase, chitinase, and catalase. In vitro antagonistic investigation showed their high efficacy against the three phytopathogens Fusarium oxysporum, Alternaria alternata, and Pythium ultimum, with inhibition percentages ranging from 20% ± 0.2% to 52.6% ± 0.2% (p ≤ 0.05). Therefore, these two endophytic bacteria were used as bio-inoculants for maize seeds, and the results showed that bacterial inoculations significantly increased the root length as well as the fresh and dry weights of the roots compared to the control plants. The Zea mays plant inoculated with the two endophytic strains BI-8 and BI-10 significantly improved (p ≤ 0.05) the growth performance as well as the nutrient uptake compared with an un-inoculated plant.
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Affiliation(s)
- Amr Fouda
- Department of Botany and Microbiology, Faculty of Science, Al-Azhar University, Nasr City, Cairo 11884, Egypt; (A.M.E.); (A.E.); (E.F.E.-B.); (M.G.B.); or (S.E.-D.H.)
| | - Ahmed M. Eid
- Department of Botany and Microbiology, Faculty of Science, Al-Azhar University, Nasr City, Cairo 11884, Egypt; (A.M.E.); (A.E.); (E.F.E.-B.); (M.G.B.); or (S.E.-D.H.)
| | - Albaraa Elsaied
- Department of Botany and Microbiology, Faculty of Science, Al-Azhar University, Nasr City, Cairo 11884, Egypt; (A.M.E.); (A.E.); (E.F.E.-B.); (M.G.B.); or (S.E.-D.H.)
| | - Ehab F. El-Belely
- Department of Botany and Microbiology, Faculty of Science, Al-Azhar University, Nasr City, Cairo 11884, Egypt; (A.M.E.); (A.E.); (E.F.E.-B.); (M.G.B.); or (S.E.-D.H.)
| | - Mohammed G. Barghoth
- Department of Botany and Microbiology, Faculty of Science, Al-Azhar University, Nasr City, Cairo 11884, Egypt; (A.M.E.); (A.E.); (E.F.E.-B.); (M.G.B.); or (S.E.-D.H.)
| | - Ehab Azab
- Department of Biotechnology, College of Science, Taif University, P.O. Box 11099, Taif 21944, Saudi Arabia;
- Botany and Microbiology Department, Faculty of Science, Zagazig University, Zagazig 44519, Sharkia, Egypt
| | - Adil A. Gobouri
- Department of Chemistry, College of Science, Taif University, P.O. Box 11099, Taif 21944, Saudi Arabia;
| | - Saad El-Din Hassan
- Department of Botany and Microbiology, Faculty of Science, Al-Azhar University, Nasr City, Cairo 11884, Egypt; (A.M.E.); (A.E.); (E.F.E.-B.); (M.G.B.); or (S.E.-D.H.)
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Abstract
One representative of each of five different pathogenic serotypes of Leptospira as well as one saprophytic strain were capable of growing on medium containing urea in place of an ammonium salt as a nitrogen source. Growth of all of the organisms tested on 1% urea was substantial, but only those that exhibited strong urease activity could grow to any appreciable extent on urea at a concentration as high as 2%. Intact urea-grown cells of the pathogenic serotypes tested (grippotyphosa and icterohaemorrhagiae) exhibited urease activity, with the level of activity of the former being considerably greater. No urease could be detected in cells of the saprophytic strain. When the pathogenic leptospires were sonicated or treated with toluene, the urease activity was greatly enhanced. When cultivated on NH(4)Cl, neither intact nor disrupted cells of any of the strains tested exhibited any urease activity. Cells of the grippotyphosa and icterohaemorrhagiae strains exhibited diauxic growth when cultivated in the presence of both NH(4)Cl and urea, whereas only monophasic growth could be detected for the saprophytic test strain. The experimental data on urea utilization and urease activity, when considered in the light of previously reported findings on leptospiral pathology, renal physiology, and the role of urease in other bacterial infections, suggests a significant role for leptospiral urease (in addition to other factors) in determining localization of the organism in the kidney and contributing to the resultant kidney pathology.
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