Bacteria Isolated from Wastewater Irrigated Agricultural Soils Adapt to Heavy Metal Toxicity While Maintaining Their Plant Growth Promoting Traits

The present study explored the plant growth promotion and bioremediation potential of bacteria inhabiting wastewater irrigated agricultural soils. Thirty out of 75 bacterial isolates (40%), 29/75 (39%) and 28/75 (37%) solubilized Zn, K and PO4 during plate essays respectively. Fifty-six percent of the isolates produced siderophores, while 30% released protease in vitro. Seventy-four percent of bacteria resisted Pb, Ni and Cd at various concentrations added to the culture media plates. Sixteen out of 75 (26%) isolates were able to fix N in Nbf medium. Among these 16 N fixers, N fixing nifH, nifD and nifK genes was detected through PCR in 8, 7 and 1 strain respectively using gene specific primers designed in the study with Enterobacter sp. having all three (nifHKD) genes. Isolated bacteria showed resemblance to diverse genera such as Bacillus, Pseudomonas, Enterobacter, Citrobacter, Acinetobacter, Serratia, Klebsiella and Enterococcus based on 16S rRNA gene sequence analysis. In addition to showing the best mineral solubilization and metal resistance potential, Citrobacter sp. and Enterobacter sp. also removed 87%, 79% and 43% and 86%, 78% and 51% of Ni, Cd and Pb, respectively, from aqueous solution. These potent bacteria may be exploited both for bioremediation and biofertilization of wastewater irrigated soils leading to sustainable agriculture.

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Isolation of plant growth-promoting Pseudomonas sp. PPR8 from the rhizosphere of Phaseolus vulgaris L.

Archives of Biological Sciences ◽

10.2298/abs150701028k ◽

2016 ◽

Vol 68 (2) ◽

pp. 363-374 ◽

Cited By ~ 4

Author(s):

Pankaj Kumar ◽

Ramesh Dubey ◽

Dinesh Maheshwari ◽

Yong-Ha Park ◽

Vivek Bajpai

Keyword(s):

Phaseolus Vulgaris ◽

Plant Growth ◽

Growth Promotion ◽

Rrna Gene ◽

Sequencing Analysis ◽

Pseudomonas Sp ◽

Pgp Traits ◽

Plant Growth Promoting ◽

Growth Promoting

In vitro screening of plant growth-promoting (PGP) traits was carried out using eight Pseudomonas spp., PPR1 to PPR8, isolated from the rhizosphere of Phaseolus vulgaris growing on the Uttarakhand Himalayan range in India. All the isolates were fast growers, positive for catalase, oxidase and urease activities, and utilized lactose and some amino acids. All the isolates were indole acetic acid (IAA) positive, however PPR8 solubilized potassium and zinc along with various other types of inorganic (tricalcium, dicalcium and zinc phosphate) and organic (calcium phytate) phosphates, as well as producing siderophore and ACC deaminase. PPR8 also produced cyanogens, extracellular chitinase, ?-1,3-glucanase, ?-1,4-glucanase and oxalate oxidase. Based on the PGP traits of all isolates, PPR8 was found to be the most potent plant growth-promoting rhizobacteria (PGPR). Further, PPR8 was identified as Pseudomonas sp. PPR8, based on 16S rRNA gene sequencing analysis. Moreover, the PGP activities of PPR8 confirmed it to be a potent biocontrol agent, inhibiting the growth of various plant pathogenic fungi. This study reveals the potential of Pseudomonas sp. PPR8 to be used as a good bioinoculant for growth promotion of common bean and for the protection of important legume crops from various deleterious phytopathogens.

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A prospectus of plant growth promoting endophytic bacterium from orchid (Vanda cristata)

BMC Biotechnology ◽

10.1186/s12896-021-00676-9 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Sujit Shah ◽

Krishna Chand ◽

Bhagwan Rekadwad ◽

Yogesh S. Shouche ◽

Jyotsna Sharma ◽

...

Keyword(s):

Plant Growth ◽

Root Colonization ◽

Endophytic Bacterium ◽

Epifluorescence Microscopy ◽

In Vitro Cultivation ◽

Rrna Gene ◽

Bacillus Spp ◽

Plant Growth Promoting ◽

Growth Promoting

Abstract Background A plant growth-promoting endophytic bacterium PVL1 isolated from the leaf of Vanda cristata has the ability to colonize with roots of plants and protect the plant. PVL1 was isolated using laboratory synthetic media. 16S rRNA gene sequencing method has been employed for identification before and after root colonization ability. Results Original isolated and remunerated strain from colonized roots were identified as Bacillus spp. as per EzBiocloud database. The presence of bacteria in the root section of the plantlet was confirmed through Epifluorescence microscopy of colonized roots. The in-vitro plantlet colonized by PVL1 as well as DLMB attained higher growth than the control. PVL1 capable of producing plant beneficial phytohormone under in vitro cultivation. HPLC and GC-MS analysis suggest that colonized plants contain Indole Acetic Acid (IAA). The methanol extract of Bacillus spp., contains 0.015 μg in 1 μl concentration of IAA. PVL1 has the ability to produce antimicrobial compounds such as ethyl iso-allocholate, which exhibits immune restoring property. One-way ANOVA shows that results were statistically significant at P ≤ 0.05 level. Conclusions Hence, it has been concluded that Bacillus spp. PVL1 can promote plant growth through secretion of IAA during root colonization and ethyl iso-allocholate to protect plants from foreign infections. Thus, this study supports to support Koch’s postulates of bacteria establishment.

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Arsenic-Redox Transformation and Plant Growth Promotion by Purple Nonsulfur Bacteria Rhodopseudomonas palustris CS2 and Rhodopseudomonas faecalis SS5

BioMed Research International ◽

10.1155/2017/6250327 ◽

2017 ◽

Vol 2017 ◽

pp. 1-8 ◽

Cited By ~ 9

Author(s):

Kanza Batool ◽

Fatima tuz Zahra ◽

Yasir Rehman

Keyword(s):

Plant Growth ◽

Plant Growth Promotion ◽

Root Length ◽

Growth Promotion ◽

Rhodopseudomonas Palustris ◽

Shoot Length ◽

Rrna Gene ◽

Purple Nonsulfur Bacteria ◽

Plant Growth Promoting ◽

Growth Promoting

Arsenic (As) is a well-known toxic metalloid found naturally and released by different industries, especially in developing countries. Purple nonsulfur bacteria (PNSB) are known for wastewater treatment and plant growth promoting abilities. As-resistant PNSB were isolated from a fish pond. Based on As-resistance and plant growth promoting attributes, 2 isolates CS2 and SS5 were selected and identified as Rhodopseudomonas palustris and Rhodopseudomonas faecalis, respectively, through 16S rRNA gene sequencing. Maximum As(V) resistance shown by R. faecalis SS5 and R. palustris CS2 was up to 150 and 100 mM, respectively. R. palustris CS2 showed highest As(V) reduction up to 62.9% (6.29±0.24 mM), while R. faecalis SS5 showed maximum As(III) oxidation up to 96% (4.8±0.32 mM), respectively. Highest auxin production was observed by R. palustris CS2 and R. faecalis SS, up to 77.18±3.7 and 76.67±2.8 μg mL−1, respectively. Effects of these PNSB were tested on the growth of Vigna mungo plants. A statistically significant increase in growth was observed in plants inoculated with isolates compared to uninoculated plants, both in presence and in absence of As. R. palustris CS2 treated plants showed 17% (28.1±0.87 cm) increase in shoot length and 21.7% (7.07±0.42 cm) increase in root length, whereas R. faecalis SS5 treated plants showed 12.8% (27.09±0.81 cm) increase in shoot length and 18.8% (6.9±0.34 cm) increase in root length as compared to the control plants. In presence of As, R. palustris CS2 increased shoot length up to 26.3% (21.0±1.1 cm), while root length increased up to 31.3% (5.3±0.4 cm), whereas R. faecalis SS5 inoculated plants showed 25% (20.7 ± 1.4 cm) increase in shoot length and 33.3% (5.4 ± 0.65 cm) increase in root length as compared to the control plants. Bacteria with such diverse abilities could be ideal for plant growth promotion in As-contaminated sites.

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Enhancement of verticillium wilt resistance in tomato transplants by in vitro co-culture of seedlings with a plant growth promoting rhizobacterium (Pseudomonas sp. strain PsJN)

Canadian Journal of Microbiology ◽

10.1139/w98-017 ◽

1998 ◽

Vol 44 (6) ◽

pp. 528-536 ◽

Cited By ~ 67

Author(s):

V K Sharma ◽

J Nowak

Keyword(s):

Plant Growth ◽

Verticillium Wilt ◽

Plant Growth Promotion ◽

Growth Promotion ◽

Disease Suppression ◽

Pseudomonas Sp ◽

Plant Growth Promoting ◽

Growth Promoting

The potential utilization of a plant growth promoting rhizobacterium, Pseudomonas sp. strain PsJN, to enhance the resistance of tomato transplants to verticillium wilt was investigated. Plant growth and disease development were tested on the disease-susceptible cultivar Bonny Best after Verticillium dahliae infection of tissue culture plantlets bacterized in vitro (by co-culturing with the bacterium) and seedlings bacterized in vivo (after 3 weeks growth in the greenhouse). Significant differences in both disease suppression and plant growth were obtained between in vitro bacterized and nonbacterized (control) plants. The degree of protection afforded by in vitro bacterization depended on the inoculum density of V. dahliae; the best and worst protection occurred at the lowest (103 conidia ·mL-1) and highest (106 conidia ·mL-1) levels, respectively. In contrast, the in vivo bacterized tomatoes did not show plant growth promotion when compared to the nonbacterized control plants. When challenged with Verticillium, significant growth differences between in vivo bacterized plants (26.8% for shoot height) and nonbacterized controls were only seen at the 3rd week after inoculation. Compared with the in vitro inoculation, there was no delay in the verticillium wilt symptom expression, even at the lowest concentration of V. dahliae, by in vivo PsJN inoculation. These results suggest that endophytic colonization of tomato tissues is required for the Verticillium-resistance responses. Plant growth promotion preceeds the disease-resistance responses and may depend on the colonization thresholds and subsequent sensitization of hosts.Key words: Pseudomonas sp., plant growth promoting rhizobacterium, Verticillium dahliae, tomato, colonization, plant growth promotion, disease suppression.

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Screening of efficient rhizobacteria associated with cauliflower (Brassica oleraceavar. botrytis L.) for plant growth promoting traits

Journal of Applied and Natural Science ◽

10.31018/jans.v9i1.1166 ◽

2017 ◽

Vol 9 (1) ◽

pp. 167-172

Author(s):

Sonal Bhardwaj ◽

Bhawna Dipta ◽

Shruti Kirti ◽

Rajesh Kaushal

Keyword(s):

Plant Growth ◽

Growth Promotion ◽

Himachal Pradesh ◽

Pgp Traits ◽

Antifungal Metabolites ◽

Stalk Rot ◽

Plant Growth Promoting ◽

Growth Promoting ◽

Phosphate Solubilizing

In the current study, a total of 25 isolates were isolated from the rhizosphere and roots of cauliflower (Brassica oleraceavar. botrytis L.) from the vicinity of Una district of Himachal Pradesh. The isolates were tested in vitro for their ability to solubilise phosphorous and produce siderophore, indole acetic acid (IAA), hydrogen cyanide (HCN) and antifungal metabolites against the soil borne pathogens. Results revealed that out of 25, only 4 rhizospheric isolates (SB5, SB11, SB8 and SB10) have maximum plant growth promoting attributes. The isolates were identified as Bacillus sp. on the basis of Bergey’s manual of systematic bacteriology. The isolate SB11 recorded highest phosphate solubilizing efficiency in solid medium (109.09%) and in liquid medium (350μg/ml). Maximum production of IAA (51.96μg/ml), siderophore (91.41%) and HCN were also observed for the same isolate. Further-more, the isolate SB11 produced highest antifungal metabolite production against Rhizoctoniasolani(37.11%), Sclerotiniasclerotiorum(41.11%), and Pythium sp. (71.11%) causing root rot, stalk rot and damping off diseases in cauliflower, respectively. The selected isolate (SB11) showed optimum growth at a pH of 7.0, 35°C temperature and 2% NaCl. On the basis of multifarious PGP-traits the SB11 isolate has tremendous potential to be used as a bioferti-lizer/bioprotectant for growth promotion and natural protection of cauliflower under low hill conditions of Himachal Pradesh.

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In Vitro Evaluation and Genome Mining of Bacillus subtilis Strain RS10 Reveals Its Biocontrol and Plant Growth-Promoting Potential

Agriculture ◽

10.3390/agriculture11121273 ◽

2021 ◽

Vol 11 (12) ◽

pp. 1273

Author(s):

Sajid Iqbal ◽

Nimat Ullah ◽

Hussnain Ahmed Janjua

Keyword(s):

Bacillus Subtilis ◽

Plant Growth ◽

Genome Analysis ◽

Growth Promotion ◽

Gene Clusters ◽

Subtilis Strain ◽

Antifungal Metabolites ◽

Plant Growth Promoting ◽

Growth Promoting

Recently, crop management has involved excessive use of chemical fertilizers and pesticides, compromising public health and environmental integrity. Rhizobacteria, which can enhance plant growth and protect plants from phytopathogen, are eco-friendly and have been attracting increasing attention. In the current study, Bacillus subtilis RS10 isolated from the rhizosphere region of Cynodon dactylon, inhibited the growth of indicator strains and exhibited in vitro plant growth-promoting traits. A whole-genome analysis identified numerous biosynthetic gene clusters encoding antibacterial and antifungal metabolites including bacillibactin, bogorol A, fengycin, bacteriocin, type III polyketides (PKs), and bacilysin. The plant growth-promoting conferring genes involved in nitrogen metabolism, phosphate solubilization, hydrogen sulfide, phytohormones, siderophore biosynthesis, chemotaxis and motility, plant root colonization, lytic enzymes, and biofilm formation were determined. Furthermore, genes associated with abiotic stresses such as high salinity and osmotic stress were identified. A comparative genome analysis indicated open pan-genome and the strain was identified as a novel sequence type (ST-176). In addition, several horizontal gene transfer events were found which putatively play a vital role in the evolution and new functionalities of a strain. In conclusion, the current study demonstrates the potential of RS10 antagonism against important pathogens and plant growth promotion, highlighting its application in sustainable agriculture.

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Analysis of the Genome of the Heavy Metal Resistant and Hydrocarbon-Degrading Rhizospheric Pseudomonas qingdaonensis ZCR6 Strain and Assessment of Its Plant-Growth-Promoting Traits

International Journal of Molecular Sciences ◽

10.3390/ijms23010214 ◽

2021 ◽

Vol 23 (1) ◽

pp. 214

Author(s):

Daria Chlebek ◽

Tomasz Płociniczak ◽

Sara Gobetti ◽

Agata Kumor ◽

Katarzyna Hupert-Kocurek ◽

...

Keyword(s):

Heavy Metal ◽

Plant Growth ◽

Contaminated Soils ◽

Growth Promotion ◽

Sulfur Metabolism ◽

Heavy Metal Resistance ◽

Metal Resistance ◽

Minimal Inhibitory Concentrations ◽

Plant Growth Promoting

The Pseudomonas qingdaonensis ZCR6 strain, isolated from the rhizosphere of Zea mays growing in soil co-contaminated with hydrocarbons and heavy metals, was investigated for its plant growth promotion, hydrocarbon degradation, and heavy metal resistance. In vitro bioassays confirmed all of the abovementioned properties. ZCR6 was able to produce indole acetic acid (IAA), siderophores, and ammonia, solubilized Ca3(PO4)2, and showed surface active properties and activity of cellulase and very high activity of 1-aminocyclopropane-1-carboxylic acid deaminase (297 nmol α-ketobutyrate mg−1 h−1). The strain degraded petroleum hydrocarbons (76.52% of the initial hydrocarbon content was degraded) and was resistant to Cd, Zn, and Cu (minimal inhibitory concentrations reached 5, 15, and 10 mM metal, respectively). The genome of the ZCR6 strain consisted of 5,507,067 bp, and a total of 5055 genes were annotated, of which 4943 were protein-coding sequences. Annotation revealed the presence of genes associated with nitrogen fixation, phosphate solubilization, sulfur metabolism, siderophore biosynthesis and uptake, synthesis of IAA, ethylene modulation, heavy metal resistance, exopolysaccharide biosynthesis, and organic compound degradation. Complete characteristics of the ZCR6 strain showed its potential multiway properties for enhancing the phytoremediation of co-contaminated soils. To our knowledge, this is the first analysis of the biotechnological potential of the species P. qingdaonensis.

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Genome sequencing and assessment of plant growth-promoting properties of a Serratia marcescens strain isolated from vermicompost

10.1101/288084 ◽

2018 ◽

Author(s):

Filipe P. Matteoli ◽

Hemanoel Passarelli-Araujo ◽

Régis Josué A. Reis ◽

Letícia O. da Rocha ◽

Emanuel M. de Souza ◽

...

Keyword(s):

Plant Growth ◽

Serratia Marcescens ◽

Genome Sequencing ◽

Growth Promotion ◽

Antibiotic Production ◽

Indole Compounds ◽

Wide Range ◽

Plant Growth Promoting ◽

Growth Promoting

ABSTRACTPlant-bacteria associations have been extensively studied for their potential in increasing crop productivity in a sustainable manner. Serratia marcescens is a Gram-negative species found in a wide range of environments, including soil. Here we describe the genome sequencing and assessment of plant-growth promoting abilities of S. marcescens UENF-22GI (SMU), a strain isolated from mature cattle manure vermicompost. In vitro, SMU is able to solubilize P and Zn, to produce indole compounds (likely IAA), to colonize hyphae and counter the growth of two phytopathogenic fungi. Inoculation of maize with SMU remarkably increased seedling growth and biomass under greenhouse conditions. The SMU genome has 5 Mb, assembled in 17 scaffolds comprising 4,662 genes (4,528 are protein-coding). No plasmids were identified. SMU is phylogenetically placed within a clade comprised almost exclusively of environmental strains. We were able to find the genes and operons that are likely responsible for all the interesting plant-growth promoting features that were experimentally described. Genes involved other interesting properties that were not experimentally tested (e.g. tolerance against metal contamination) were also identified. The SMU genome harbors a horizontally-transferred genomic island involved in antibiotic production, antibiotic resistance, and anti-phage defense via a novel ADP-ribosyltransferase-like protein and possible modification of DNA by a deazapurine base, which likely contributes to the SMU competitiveness against other bacteria. Collectively, our results suggest that S. marcescens UENF-22GI is a strong candidate to be used in the enrichment of substrates for plant growth promotion or as part of bioinoculants for Agriculture.

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In vitro antagonistic potential, plant growth-promoting activity and indole-3-acetic acid producing trait of bacterial isolates from spent mushroom substrate of Agaricus bisporus

Journal of Agricultural and Marine Sciences [JAMS] ◽

10.24200/jams.vol25iss2pp22-29 ◽

2020 ◽

Vol 25 (2) ◽

pp. 22

Author(s):

Rethinasamy Velazhahan ◽

Shima Nasser Hamed Al-Mamari ◽

Abdullah Mohammed Al-Sadi ◽

Issa Hashil Al-Mahmooli ◽

S. P. Sathish Babu

Keyword(s):

Plant Growth ◽

Agaricus Bisporus ◽

Growth Promotion ◽

Inhibition Zone ◽

Bacterial Isolates ◽

Plant Growth Promoting ◽

Antagonistic Potential ◽

Growth Promoting ◽

Indole 3 Acetic Acid

Spent mushroom substrate (SMS) is widely used as fertilizer and to control plant diseases. The microorganisms surviving in SMS play a crucial role in plant growth promotion and biocontrol properties of SMS. In this study, an effort was made to isolate and characterize the bacterial species present in the SMS of Agaricus bisporus and to study their antagonistic potential, plant growth-promoting ability and indole-3-acetic acid (IAA) producing trait. Six different bacterial isolates exhibiting morphological variabilities were obtained from the SMS by serial dilution technique. On the basis of 16S rRNA gene sequences, these isolates were identified as Staphylococcus epidermidis (Sh1 and Sh3), S. aureus (Sh2), Bacillus albus (Sh4), Delftia lacustris (Sh6) and Comamonas aquatica (Sh7). These bacterial strains were assayed for their antagonism against Pythium aphanidermatum, a phytopathogenic oomycete. The results of in vitro dual culture assay revealed that all the 6 bacterial isolates showed low levels of suppression of P. aphanidermatum and recorded less than 5 mm inhibition zone. Among the bacterial isolates, S. epidermidis Sh3 recorded the maximum inhibition zone of 4.2 mm. Plant growth promotion test using roll paper towel method revealed that C. aquatica Sh7, B. albus Sh4, D. lacustris Sh6 and S. epidermidis Sh3 caused a significant increase in seedling vigour of cucumber compared to control. The seeds treated with the bacterial isolate C. aquatica Sh7 showed the maximum seedling vigor. Assessment of in vitro production of IAA by the bacterial isolates revealed that the bacterial isolates highly varied (ranging from 0.28 to 9.25 mg L-1) in their potential for production of IAA. The maximum amount of IAA was produced by C. aquatica Sh7 (9.25 mg L-1), while the minimum was produced by S. epidermidis Sh1 (0.28 mg L-1).

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Genomic and Metabolomic Insights into Secondary Metabolites of the Novel Bacillus halotolerans Hil4, an Endophyte with Promising Antagonistic Activity against Gray Mold and Plant Growth Promoting Potential

Microorganisms ◽

10.3390/microorganisms9122508 ◽

2021 ◽

Vol 9 (12) ◽

pp. 2508

Author(s):

Eirini-Evangelia Thomloudi ◽

Polina C. Tsalgatidou ◽

Eirini Baira ◽

Konstantinos Papadimitriou ◽

Anastasia Venieraki ◽

...

Keyword(s):

Plant Growth ◽

Growth Promotion ◽

Gene Clusters ◽

Gray Mold ◽

Antagonistic Activity ◽

Future Research ◽

Single Culture ◽

Plant Growth Promoting ◽

Growth Promoting

The endophytic bacterial strain Hil4 was isolated from leaves of the medicinal plant Hypericum hircinum. It exhibited antifungal activity against Botrytis cinerea and a plethora of plant growth promoting traits in vitro. Whole genome sequencing revealed that it belongs to Bacillus halotolerans and possesses numerous secondary metabolite biosynthetic gene clusters and genes involved in plant growth promotion, colonization, and plant defense elicitation. The Mojavensin cluster was present in the genome, making this strain novel among plant-associated B. halotolerans strains. Extracts of secreted agar-diffusible compounds from single culture secretome extracts and dual cultures with B. cinerea were bioactive and had the same antifungal pattern on TLC plates after bioautography. UHPLC-HRMS analysis of the single culture secretome extract putatively annotated the consecutively produced antimicrobial substances and ISR elicitors. The isolate also proved efficient in minimizing the severity of gray mold post-harvest disease on table grape berries, as well as cherry tomatoes. Finally, it positively influenced the growth of Arabidopsis thaliana Col-0 and Solanum lycopersicum var. Chondrokatsari Messinias after seed biopriming in vitro. Overall, these results indicate that the B. halotolerans strain Hil4 is a promising novel plant growth promoting and biocontrol agent, and can be used in future research for the development of biostimulants and/or biological control agents.

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