In the search for new and active natural resources and to find friendly environmental solutions for yield increase and crop protection, Actinobacteria (especially
From all known antibiotics that are produced by microorganisms, Actinobacteria produces two-thirds of them.
The
The selection of biological control agents usually starts with an
Upon the beginning of sporulation and development of aerial hyphae, the production of
On the other hand, some fungal pathogens require iron (Fe) for their pathogenicity. The beneficial rhizobacteria that produce siderophores are chelating ferric iron from the surrounding environment and subsequently could inhibit the growth of pathogen via iron competition (Expert et al. 2012). At the same time, these bacteria provide the iron available for plant growth and work as plant inducers.
Otherwise, the environment is highly contaminated due to agrochemical usage like pesticides and/or fertilizers. Some opponents expressed concern about the heavy use of pesticides, which has led to a significant shift in people’s attitudes to pesticide use in both the surrounding environment and agriculture (Yoon et al. 2013; Nicolopoulou-Stamati et al. 2016; Brauer et al. 2019).
Characteristics of eleven Actinomycetes strains.
Symbol of isolate | Pigmentation | Opacity of colony | Colony consistency | Growth under the surface of liquid media |
---|---|---|---|---|
Brown | Opaque | Rough | Sediment of balls | |
White | Opaque | Rough | Sediment of balls | |
Yellow* | Opaque | Rough | Sediment of balls | |
Yellow | Opaque | Rough | Sediment of balls | |
Actino7 | Red | Opaque | Rough | Sediment of balls |
Cream | Opaque | Rough | Sediment of balls | |
Cream | Opaque | Rough | Sediment of balls | |
Dark brown | Opaque | Rough | Sediment of balls | |
Actino10 | Cream light pink | Opaque | Rough | Sediment of balls |
Actino11 | Cream | Opaque | Rough | Sediment of balls |
Yellow** | Opaque | Rough | Sediment of balls |
– Yellow pigment colored the surrounding media
– Dark green pigment colored the surrounding media
Scanning electron microscopy of
Identified Streptomyces strains via 16S rRNA amplicon sequencing and their similarity with identified strains at the NCBI website.
No. | The isolated strain | Similarity (%) | |
---|---|---|---|
1 | 99.46 | ||
2 | 99.85 | ||
3 | 99.62 | ||
4 | 99.46 | ||
5 | 99.23 | ||
6 | 99.54 | ||
7 | 99.46 | ||
8 | 99.77 |
Antagonism of eight identified
Isolates | Tested Fungi* | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
F. mon | F. so | F. ox | F. gra | Collet | Bot | Alt | Rhiz | Myro | Thiel | Total | |
– | – | +++ | – | – | – | – | – | – | – | 1 | |
– | – | – | – | – | – | – | – | – | – | 0 | |
+++ | +++ | +++ | +++ | +++ | +++ | +++ | +++ | +++ | +++ | 10 | |
– | – | – | – | +++ | +++ | +++ | +++ | – | – | 4 | |
Actino7 | + | +++ | + | +++ | – | +++ | +++ | +++ | +++ | +++ | 5 |
– | – | – | – | – | – | – | – | – | – | 0 | |
– | – | – | – | – | – | – | – | – | – | 0 | |
– | – | – | – | – | – | – | – | – | – | 0 | |
Actino10 | +++ | +++ | – | +++ | – | – | – | 3 | |||
Actino11 | 0 | ||||||||||
+++ | +++ | +++ | +++ | +++ | +++ | +++ | +++ | +++ | +++ 16 m | 10 | |
Total | 3 | 3 | 4 | 3 | 4 | 3 | 5 | 3 | 2 | 3 |
+ – The
F. ox –
Antagonistic activity of
The antagonism effect of eight identified
Isolates | Total | |||
---|---|---|---|---|
+ 3 mm | – | – | 1 | |
– | – | – | 1 | |
– | + 12 mm | Trace 3 mm | 2 | |
– | – | – | 0 | |
– | – | – | 0 | |
– | – | – | 0 | |
– | – | – | 0 | |
– | – | – | 0 |
Antibacterial activity of some selected isolated
The production of siderophores, extracellular indole-3-acetic acid (IAA) and phosphor fixing of eleven isolated
Isolate | Iron1 | Phosphor2 | IAA3 µg/ml | |||
---|---|---|---|---|---|---|
Reaction | Width | D/D colony | h/c | |||
++ | 2 mm | 9.5/5.5 | 1.98 | + | 77.19 | |
++ | 1.5 mm | 10.1/7.5 | 2.15 | + | 89.36 | |
+ | 1 mm | 11/8 | 1.67 | Trace | 86.66 | |
++ | 2.5 mm | 11/5.5 | 3.36 | – | 72.26 | |
Actino7 | +++ | 5 mm | 16.5/8 | 4.25 | – | 112.96 |
++ | 2 mm | 11.5/7.5 | 2.35 | – | 43.65 | |
+++ | 5 mm | 14/4 | 12.25 | + | 99.3 | |
+++ | 11 mm | 24/3 | 64 | Trace | 75.6 | |
Actino10 | +++ | 10 mm | 25.5/4.5 | 32.1 | + | 172.13 |
Actino11 | +++ | 9 mm | 20/3.5 | 32.65 | – | 270.33 |
+++ | 11.5 mm | 28.5/6 | 22.56 | + | 273.02 |
– + A thin yellow area surrounding the colony (about 1 mm width), ++ less than 5 mm width of the yellow area surrounding the colony, +++ more than 5 mm width of the yellow area surrounding the colony, D = diameter, h/c = halo zone area/colony area
– + A thin transparent area surrounding the colony (about 1 mm width), ++ less than 5 mm width of the transparent area surrounding the colony, +++ more than 5 mm width of the transparent area surrounding the colony
– Quantitative estimation of IAA as microgram per ml according the equation: y = 185.8x + 41.05
Iron cheating of isolated eleven
Effects of
% Cells Viability (Mean + SD) | Cells Viability (%) (Mean ± SD) | ||
---|---|---|---|
Untreated cells | 98.3 ± 8.2 | Untreated cells | 99.1 ± 6.1 |
20 | 98.2 ± 9.2 | 20 | 99.2 ± 5.5 |
40 | 97.4 ± 6.8 | 40 | 98.3 ± 6.6 |
60 | 98.5 ± 7.3 | 60 | 97.1 ± 4.6 |
80 | 97.3 ± 9.6 | 80 | 98.2 ± 7.3 |
100 | 96.2 ± 9.1 | 100 | 98.3 ± 8.8 |
120 | 98.4 ± 7.2 | 120 | 97.7 ± 9.5 |
140 | 98.8 ± 9.5 | 140 | 99.1 ± 6.4 |
160 | 96.2 ± 9.1 | 160 | 98.2 ± 7.2 |
180 | 98.2 ± 8.2 | 180 | 97.1 ± 7.3 |
200 | 97.1 ± 8.5 | 200 | 98.3 ± 9.5 |
Phylogenetic tree based on 16S rRNA sequences. The evolutionary history was inferred by using the Maximum Likelihood method and Tamura-Nei model. The tree with the highest log likelihood (–4351.16) is shown. Initial tree for the heuristic search were obtained automatically by applying the Maximum Parsimony method. This analysis involved 38 nucleotide sequences. Evolutionary analyses were conducted in MEGA X.
Plant growth-promoting activities like siderophore and auxin production or phosphate dissolving, helps plants to grow up.
In this work, based on the 16S rRNA amplicon sequences, eight