In vitro study of biocontrol potential of rhizospheric Pseudomonas aeruginosa against Fusarium oxysporum f. sp. cucumerinum

Tian

Egypt J Biol Pest Control

et al. 2020

Poplar anthracnose is one of the most serious diseases caused by the fungal pathogen Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. Biocontrol is an efficient green way for the disease control, and numerous researches have focused on exploring the potential biocontrol bacteria strains against C. gloeosporioides. In this study, antifungal activities against C. gloeosporioides of 108 rhizosphere soil isolates from healthy polar plants were investigated in vitro by the dual culture assay. The results suggested that strain ZSH-1 showed the highest level of antifungal activity, as it inhibited C. gloeosporioides at a distance of 10.00 mm. Based on the morphological, physiological-biochemical characteristics, and phylogeny analysis, strain ZSH-1 was identified as Bacillus subtilis. The sterile culture filtrate, crude protein, and crude lipopeptide extracts from the culture filtrate, and volatile compound(s) of ZSH-1 displayed a strong antagonism towards 7 fungal phytopathogens (C. gloeosporioides, Fusarium oxysporum, Alternaria tenuissima, Cytospora chrysosperma, Botryosphaeria dothidea, Mucor sp., and Absidia sp.), with inhibition rates ranging from 44.0 to 89.1%, 26.7 to 85.4%, 11.6 to 89.7%, and 7.8 to 63.2%, respectively. Moreover, ZSH-1 exhibited cell wall-degrading traits by producing 3 lytic enzymes (cellulose, β-1,3-glucanase, and protease). Finally, the greenhouse studies also revealed that strain ZSH-1 had a 47.6% (12 days) efficacy in controlling poplar anthracnose when compared with the control. In concluding, obtained results demonstrate the potential biocontrol effect of B. subtilis ZSH-1, and it can be used as a promising biocontrol agent against poplar anthracnose and other fungal phytopathogens.

Section: Resultsmentioning

confidence: 99%

Biological control of poplar anthracnose caused by Colletotrichum gloeosporioides (Penz.) Penz. & Sacc.

Tian

Egypt J Biol Pest Control

et al. 2020

Front. Bioeng. Biotechnol.

“…Since many years, Pseudomonas sp. are known to be used as biocontrol agents (Islam et al, 2018). Along with other traits such as antibiotics, proteolytic and cellulolytic enzymes, volatile compounds, siderophores, BS is also one among them.…”

Section: Discussionmentioning

confidence: 99%

“…They have been documented since many years as plant growth promoters, bioremediation agents and biocontrol agents. Several strains of P. aeruginosa are involved in plant growth promotion ( Islam et al, 2018 ; Uzair et al, 2018 ) while some strains are known to be opportunistic pathogens ( Lyczak et al, 2000 ). However, Jan et al (2011) have reviewed that Pseudomonas isolated from close association of plants are beneficial and they exert antagonistic effect only against plant pathogens.…”

Section: Introductionmentioning

confidence: 99%

Pseudomonas aeruginosa RTE4: A Tea Rhizobacterium With Potential for Plant Growth Promotion and Biosurfactant Production

Chopra

Bobate

Rahi

et al. 2020

Tea is an ancient non-alcoholic beverage plantation crop cultivated in the most part of Assam, India. Being a long-term monoculture, tea plants are prone to both biotic and abiotic stresses, and requires massive amounts of chemicals as fertilizers and pesticides to achieve worthy crop productivity. The rhizosphere bacteria with the abilities to produce phytohormone, secreting hydrolytic enzyme, biofilm formation, biocontrol activity provides induced systemic resistance to plants against pathogens. Thus, plant growth promoting (PGP) rhizobacteria represents as an alternative candidate to chemical inputs for agriculture sector. Further, deciphering the secondary metabolites, including biosurfactant (BS) allow developing a better understanding of rhizobacterial strains. The acidic nature of tea rhizosphere is predominated by Bacillus followed by Pseudomonas that enhances crop biomass and yield through accelerating uptake of nutrients. In the present study, a strain Pseudomonas aeruginosa RTE4 isolated from tea rhizosphere soil collected from Rosekandy Tea Garden, Cachar, Assam was evaluated for various plant-growth promoting attributes. The strain RTE4 produces indole acetic acid (74.54 µg/ml), hydrolytic enzymes, and solubilize tri-calcium phosphate (46 µg/ml). Bio-control activity of RTE4 was recorded against two foliar fungal pathogens of tea (Corticium invisium and Fusarium solani) and a bacterial plant pathogen (Xanthomonas campestris). The strain RTE4 was positive for BS production in the preliminary screening. Detailed analytical characterization through TLC, FTIR, NMR, and LCMS techniques revealed that the strain RTE4 grown in M9 medium with glucose (2% w/v) produce dirhamnolipid BS. This BS reduced surface tension of phosphate buffer saline from 71 to 31 mN/m with a critical micelle concentration of 80 mg/L. Purified BS of RTE4 showed minimum inhibitory concentration of 5, 10, and 20 mg/ml against X. campestris, F. solani and C. invisium, respectively. Capability of RTE4 BS to be employed as a biofungicide as compared to Carbendazim-commercially available fungicide is also tested. The strain RTE4 exhibits multiple PGP attributes along with production of di-rhamnolipid BS. This gives a possibility to produce di-rhamnolipid BS from RTE4 in large scale and explore its applications in fields as a biological alternative to chemical fertilizer.

“…Also, Islam et al, 2018 showed that P. aeruginosa RKA5 inhibited mycelia growth of F. oxysporum f. sp. cucumerinum [41]. On the other hand, Ahmedzedah et al, 2006 reported that 13 out of 47 fluorescent Pseudomonas isolates showed antagonistic effects against Fusarium sp.…”

Section: Discussionmentioning

confidence: 99%

Maximization of Siderophores Production from Biocontrol Agents, Pseudomonas aeruginosa F2 and Pseudomonas fluorescens JY3 Using Batch and Exponential Fed-Batch Fermentation

et al. 2020

Twenty fluorescent Pseudomonas isolates were tested for their ability to produce siderophores on chrome azurol S (CAS) agar plates and their antagonistic activity against six plant pathogenic fungal isolates was assessed. Scaling-up production of siderophores from the promising isolates, P. aeruginosa F2 and P. fluorescens JY3 was performed using batch and exponential fed-batch fermentation. Finally, culture broth of the investigated bacterial isolates was used for the preparation of two economical bioformulations for controlling Fusarium oxysporum and Rhizoctonia solani. The results showed that both isolates yielded high siderophore production and they were more effective in inhibiting the mycelial growth of the tested fungi compared to the other bacterial isolates. Exponential fed-batch fermentation gave higher siderophore concentrations (estimated in 10 µL), which reached 67.05% at 46 h and 45.59% at 48 h for isolates F2 and JY3, respectively, than batch fermentation. Formulated P. aeruginosa F2 and P. fluorescens JY3 decreased the damping-off percentage caused by F. oxysporum with the same percentage (80%), while, the reduction in damping-off percentage caused by R. solani reached 87.49% and 62.5% for F2 and JY3, respectively. Furthermore, both formulations increased the fresh and dry weight of shoots and roots of wheat plants. In conclusion, bio-friendly formulations of siderophore-producing fluorescent Pseudomonas isolates can be used as biocontrol agents for controlling some plant fungal diseases.