Isolation and identification of chromium-tolerant bacterial strains and their potential to promote plant growth

Remediation and management of Chromium (Cr) contaminated soils for safe usage has been a serious challenge. The aim of present work was to isolate and identify Cr tolerant bacterial strains and assessing their plant growth promoting potential under controlled conditions. Soil samples were collected from Gujrat District, Pakistan, and analyzed for Cr content and bacteria isolation. In-vitro screening was done for chromium tolerance and plant growth-promoting (PGP) abilities. The tolerant isolates which also exhibited PGP abilities were used as inoculants in germination and pot trial experiment. The isolates A5 and A6, identified as Pseudomonas plecoglossicida and Staphylococci saprophyticus through 16S rRNA gene sequencing, were found to be tolerant up to 700 mg L-1 of Cr (VI). Both were effective in solubilizing phosphate but only A5 (Pseudomonas plecoglossicida) was able to produce indole acetic acid. A5 also increased the percentage of seed germination from 17 to 46% and spinach plant’s biomass by 44% with respect to the control. Keeping in view the results obtained, A5 (Pseudomonas plecoglossicida) appeared as the best species that was able to tolerate Cr stress and promote plant growth. Further, it can be developed as a bio-inoculant for non-food agricultural applications for remediation of Cr contaminated soils.

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Bioprospecting of elite plant growth-promoting bacteria for the maize crop

Acta Scientiarum Agronomy ◽

10.4025/actasciagron.v42i1.44364 ◽

2020 ◽

Vol 42 ◽

pp. e44364 ◽

Cited By ~ 1

Author(s):

Angela Cristina Ikeda ◽

Daiani Cristina Savi ◽

Mariangela Hungria ◽

Vanessa Kava ◽

Chirlei Glienke ◽

...

Keyword(s):

Plant Growth ◽

Plant Growth Promoting Bacteria ◽

Bacterial Strains ◽

Maize Crop ◽

Agriculture Sustainability ◽

Plant Growth Promoting ◽

Promote Plant Growth ◽

Growth Promoting ◽

Biological Nitrogen

The use of plant growth-promoting bacteria (PGPB), which aims to replace chemical fertilizers and biological control, is a goal for achieving agriculture sustainability. In this scenario, our goal was to identify and evaluate the potential of bacteria isolated from maize roots to promote plant growth and be used as inoculants. We evaluated 173 bacterial strains isolated from the maize (Zea mays L.) rhizosphere for the properties of their PGPB in vitro. Twelve strains were positive for siderophores, indole acetic acid (IAA) production, biological nitrogen fixation (BNF), and phosphate solubilization. Sequence analysis of 16S rRNA identified these strains as belonging to the genera Cellulosimicrobium, Stenotrophomonas, Enterobacter, and Bacillus. The elite strains were evaluated under greenhouse conditions upon the inoculation of two maize hybrids, ATL100 and KWX628. The ability of the isolates to promote plant growth was dependent on the maize genotype; Enterobacter sp. LGMB208 showed the best ability to promote growth of hybrid ATL100, while Enterobacter sp. strains LGMB125, LGMB225, and LGMB274 and Cellulosimicrobium sp. strain LGMB239 showed the best ability to promote growth of hybrid KWX628. The results highlight the potential of bacterial genera little explored as maize PGPB but indicate the need to investigate their interactions with different plant genotypes.

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Role of Two Plant Growth-Promoting Bacteria in Remediating Cadmium-Contaminated Soil Combined with Miscanthus floridulus (Lab.)

Plants ◽

10.3390/plants10050912 ◽

2021 ◽

Vol 10 (5) ◽

pp. 912

Author(s):

Shuming Liu ◽

Hongmei Liu ◽

Rui Chen ◽

Yong Ma ◽

Bo Yang ◽

...

Keyword(s):

Plant Growth ◽

Contaminated Soils ◽

Translocation Factor ◽

Plant Growth Promoting Bacteria ◽

Bacterial Strains ◽

Pgp Traits ◽

Cd Tolerance ◽

Plant Growth Promoting ◽

Growth Promoting ◽

Cd Translocation

Miscanthus spp. are energy plants and excellent candidates for phytoremediation approaches of metal(loid)s-contaminated soils, especially when combined with plant growth-promoting bacteria. Forty-one bacterial strains were isolated from the rhizosphere soils and roots tissue of five dominant plants (Artemisia argyi Levl., Gladiolus gandavensis Vaniot Houtt, Boehmeria nivea L., Veronica didyma Tenore, and Miscanthus floridulus Lab.) colonizing a cadmium (Cd)-contaminated mining area (Huayuan, Hunan, China). We subsequently tested their plant growth-promoting (PGP) traits (e.g., production of indole-3-acetic acid, siderophore, and 1-aminocyclopropane-1-carboxylate deaminase) and Cd tolerance. Among bacteria, two strains, Klebsiella michiganensis TS8 and Lelliottia jeotgali MR2, presented higher Cd tolerance and showed the best results regarding in vitro growth-promoting traits. In the subsequent pot experiments using soil spiked with 10 mg Cd·kg−1, we investigated the effects of TS8 and MR2 strains on soil Cd phytoremediation when combined with M. floridulus (Lab.). After sixty days of planting M. floridulus (Lab.), we found that TS8 increased plant height by 39.9%, dry weight of leaves by 99.1%, and the total Cd in the rhizosphere soil was reduced by 49.2%. Although MR2 had no significant effects on the efficiency of phytoremediation, it significantly enhanced the Cd translocation from the root to the aboveground tissues (translocation factor > 1). The combination of K. michiganensis TS8 and M. floridulus (Lab.) may be an effective method to remediate Cd-contaminated soils, while the inoculation of L. jeotgali MR2 may be used to enhance the phytoextraction potential of M. floridulus.

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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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Micro-remediation of chromium contaminated soils

PeerJ ◽

10.7717/peerj.6076 ◽

2018 ◽

Vol 6 ◽

pp. e6076 ◽

Cited By ~ 7

Author(s):

Hadia -e- Fatima ◽

Ambreen Ahmed

Keyword(s):

Plant Growth ◽

Contaminated Soils ◽

Crop Production ◽

Lens Culinaris ◽

Production Plant ◽

Plant Growth Promoting Bacteria ◽

Bacterial Strains ◽

Soil Release ◽

Plant Growth Promoting ◽

Growth Promoting

Bacteria are tiny organisms which are ubiquitously found in the environment. These microscopic living bodies are responsible for the flow of nutrients in biogeochemical cycles and fertility imparted to the soil. Release of excessive chromium in agricultural soils due to rapid growth of industries may result in minimizing the fertility of soil in future, which will lead to reduction in crop production. Plant growth promoting bacteria (PGPB) are beneficial to the environment, some of which can tolerate chromium and protect plants against heavy metal stress. The current study aims to identify such chromium-tolerant auxin-producing rhizobacteria and to investigate their inoculation effects on the growth characteristics of Lens culinaris in chromium polluted soils by using two different chromium salts i.e., K2Cr2O7 and K2CrO4 in varying concentrations (0, 50, 100, 200, 400 and 500 µgml−1). The results revealed that Bacillus species are efficient in significantly reducing the deleterious effects of Cr. These effective bacterial strains were able to stimulate the growth of metal effected plants of Lens culinaris which were grown in chromium contaminated environment. Therefore, these plant growth promoting rhizobacteria PGPRs, having both auxin production potential and chromium-resistance ability, are considered as efficient micro-factories against chromium pollution.

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Selection and Characterization of Burkholderia spp. for Their Plant-Growth Promoting Effects and Influence on Maize Seed Germination

Frontiers in Soil Science ◽

10.3389/fsoil.2021.805094 ◽

2022 ◽

Vol 1 ◽

Author(s):

Isaneli Batista dos Santos ◽

Arthur Prudêncio de Araújo Pereira ◽

Adijailton José de Souza ◽

Elke Jurandy Bran Nogueira Cardoso ◽

Flaviana Gonçalves da Silva ◽

...

Keyword(s):

Seed Germination ◽

Quorum Sensing ◽

Genetic Variability ◽

Plant Growth ◽

Bacterial Strains ◽

Initial Development ◽

Corn Seed ◽

Plant Growth Promoting ◽

Promote Plant Growth ◽

Growth Promoting

Burkholderia sp. is a bacterial genus extremely versatile in the environment and has been reported for a great potential to promote plant growth via different mechanisms. Here we evaluate the plant growth-promoting mechanisms in twenty-six Burkholderia strains. Strains were evaluated for their ability to promote plant growth by means of: indole-3-acetic acid (IAA) production under different conditions of pH, salt stress and the presence or absence of L-tryptophan; exopolysaccharides (EPS) production and quorum sensing (ALH). The strains were also characterized in terms of their genetic variability and species identification through Sanger sequencing. Then, the bacteria most responsive in the greatest number of plant-growth promotion mechanisms were selected for a corn seed germination test. All bacteria synthesized IAA in medium with 0.0 or 5.0 mM of L-tryptophan in combination with either 1 or 5% of NaCl, and pH values of either 4.5 or 7.2. The EPS production was confirmed for 61.54% of the bacterial strains. Quorum sensing also occurred in 92.3% of the selected bacteria. The Jaccard similarity coefficient revealed 16 clusters with high genetic variability between bacterial strains. Bacterial strains were assigned to seven species: B. anthina, B. cepacia, B. gladioli, B. ambifaria, B. graminis, B. heleia, and Burkholderia spp. The corn seed bacterization did not affect the germination velocity index (GSI), as well as the first count of germinated seeds (FC). However, inoculations formulated with B. heleia strain G28, B. gladioli strain UAGC723, and B. graminis strain UAGC348 promoted significant increases in root length, seedling height and fresh and dry seedling phytomass, respectively. These results indicate the high biotechnological potential of several strains in the genus Burkholderia sp. as seed inoculants, favoring germination and seedling initial development.

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

Sustainability ◽

10.3390/su13147792 ◽

2021 ◽

Vol 13 (14) ◽

pp. 7792

Author(s):

Abdul Wahab Ajmal ◽

Saleha Saroosh ◽

Shah Mulk ◽

Muhammad Nadeem Hassan ◽

Humaira Yasmin ◽

...

Keyword(s):

Plant Growth ◽

Agricultural Soils ◽

Culture Media ◽

Growth Promotion ◽

Metal Resistance ◽

Rrna Gene ◽

Gene Sequence Analysis ◽

Plant Growth Promoting ◽

Growth Promoting

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, Characterization, and Evaluation of Native Rhizobacterial Consortia Developed From the Rhizosphere of Rice Grown in Organic State Sikkim, India, and Their Effect on Plant Growth

Frontiers in Microbiology ◽

10.3389/fmicb.2021.713660 ◽

2021 ◽

Vol 12 ◽

Author(s):

Mingma Thundu Sherpa ◽

Laxuman Sharma ◽

Niladri Bag ◽

Sayak Das

Keyword(s):

Plant Growth ◽

Plant Pathogens ◽

Burkholderia Cenocepacia ◽

Growth And Yield ◽

Root Weight ◽

Bacterial Strains ◽

Plant Growth Promoting ◽

Growth Promoting ◽

Large Cardamom

Eight rhizospheric bacteria were isolated from the organic paddy fields of Sikkim, India, and identified as Pseudomonas kribbensis KSB, Burkholderia cenocepacia SRD, Kosakonia oryzendophytica YMA7, Pseudomonas rhodesiae SRB, Bacillus sp. ARA, Paenibacillus polymyxa COW3, Bacillus aryabhattai PSB2, and Bacillus megaterium PSB1. They showed plant growth-promoting attributes in rice and have bio-control potential against phytopathogen Colletotrichum gloeosporioides of large cardamom (Amomum subulatum). Burkholderia cenocepacia SRD showed production of indole acetic acid and ammonia and solubilization of phosphate and potassium and also possessed nitrogen fixation potential. It showed antagonistic activity against two other plant pathogens of large cardamom, viz., Curvularia eragrostidis and Pestalotiopsis sp., under in vitro conditions. The liquid bacterial consortium was prepared using the bacterial strains SRB, PSB1, and COW3 (Consortia-1); PSB2, SRD, and COW3 (Consortia-2); and COW3, KSB, and YMA7 (Consortia-3) to increase the growth and yield of rice plants under organic farming conditions. Greenhouse and field studies showed that the Consortia-3 had the highest plant growth-promoting activity. Consortia-3 demonstrated better agronomic performance in terms of root length (9.5 cm),number of leaflets per plant (5.3), grains per panicle (110.6), test grain weight (27.4 g), dry root weight per plant (0.73 g), and total dry biomass per plant (8.26 g).

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Screening of plant growth promoting bacteria associated with barley plants (Hordeum vulgare L.) cultivated in South Brazil

Biota Neotropica ◽

10.1590/1676-06032015010514 ◽

2015 ◽

Vol 15 (2) ◽

Cited By ~ 6

Author(s):

Andress P. Pontes ◽

Rocheli de Souza ◽

Camille E. Granada ◽

Luciane M.P. Passaglia

Keyword(s):

Hordeum Vulgare ◽

Plant Growth ◽

Tricalcium Phosphate ◽

Future Application ◽

Rrna Gene ◽

Plant Growth Promoting Bacteria ◽

Bacterial Strains ◽

Hordeum Vulgare L ◽

Plant Growth Promoting ◽

Growth Promoting

The occurrence of associations between bacteria and plant roots may be beneficial, neutral or detrimental. Plant growth promoting (PGP) bacteria form a heterogeneous group of beneficial microorganisms that can be found in the rhizosphere, the root surfaces or in association with host plant. The aim of this study was to isolate and characterize PGP bacteria associated to barley plants (Hordeum vulgare L.) aiming a future application as agricultural inoculant. One hundred and sixty bacterial strains were isolated from roots or rhizospheric soil of barley based on their growth in nitrogen-free selective media. They were evaluated for their ability to produce indolic compounds (ICs) and siderophores, and to solubilize tricalcium phosphate inin vitro assays. Most of them (74%) were able to synthesize ICs in the presence of the precursor L-tryptophan, while 57% of the isolates produced siderophores in Fe-limited liquid medium, and 17% were able to solubilize tricalcium phosphate. Thirty-two isolates possessing different PGP characteristics were identified by partial sequencing of their 16S rRNA gene. Strains belonging to Cedecea andMicrobacterium genera promoted the growth of barley plants in insoluble phosphate conditions, indicating that these bacteria could be used as bioinoculants contributing to decrease the amount of fertilizers applied in barley crops.

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In vitro Screening and Optimization of IAA Production from Plant Growth Promoting Rhizobacteria Burkholderia cepacia UPMB3

Plant Tissue Culture and Biotechnology ◽

10.3329/ptcb.v28i1.37195 ◽

2018 ◽

Vol 28 (1) ◽

pp. 25-34

Author(s):

Waheeda Parvin ◽

Quazi Shirin Akhter Jahan ◽

Md Mahbubur Rahman ◽

Mui Yun Wong

Keyword(s):

Plant Growth ◽

Oil Palm ◽

Burkholderia Cepacia ◽

Plant Growth Promoting Rhizobacteria ◽

Leaf Length ◽

Plant Growth Promoting ◽

Promote Plant Growth ◽

Growth Promoting ◽

Layer Chromatography

Burkholderia cepacia UPMB3 is an important plant growth promoting rhizobacteria isolated from oil palm rhizosphere which is considered to promote plant growth directly or indirectly. The IAA was extracted, purified, detected and confirmed by thin layer chromatography analyses f r om t h e strain UPMB3 of B. cepacia. Rf value was compared with the authentic IAA. Maximum 50 μg/ml IAA was produced in the medium supplemented with 4 mg/ml L-tryptophan, under shaken conditions at 150 rpm in seven days incubation at pH 7. The bacterial extract significantly influenced the growth of oil palm seedlings producing shoot, root, leaf and leaf length compared to control.Plant Tissue Cult. & Biotech. 28(1): 25-34, 2018 (June)

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Isolation and identification of plant growth promoting rhizobacteria from maize (Zea mays L.) rhizosphere and their plant growth promoting effect on rice (Oryza sativa L.)

Journal of Plant Protection Research ◽

10.1515/jppr-2017-0020 ◽

2017 ◽

Vol 57 (2) ◽

pp. 144-151 ◽

Cited By ~ 12

Author(s):

Arun Karnwal

Keyword(s):

Zea Mays ◽

Plant Growth ◽

Growth Promotion ◽

Oryza Sativa L ◽

Plant Growth Promoting Rhizobacteria ◽

Promoting Effect ◽

Isolation And Identification ◽

Plant Growth Promoting ◽

Growth Promoting

AbstractThe use of plant growth promoting rhizobacteria is increasing in agriculture and gives an appealing manner to replace chemical fertilizers, pesticides, and dietary supplements. The objective of our research was to access the plant growth promotion traits ofPseudomonas aeruginosa,P. fluorescensandBacillus subtilisisolated from the maize (Zea maysL.) rhizosphere.In vitrostudies showed that isolates have the potential to produce indole acetic acid (IAA), hydrogen cyanide, phosphate solubilisation, and siderophore. RNA analysis revealed that two isolates were 97% identical toP. aeruginosastrain DSM 50071 andP. aeruginosastrain NBRC 12689 (AK20 and AK31), while two others were 98% identical toP. fluorescensstrain ATCC 13525,P. fluorescensstrain IAM 12022 (AK18 and AK45) and one other was 99% identical toB. subtilisstrain NCDO 1769 (AK38). Our gnotobiotic study showed significant differences in plant growth variables under control and inoculated conditions. In the present research, it was observed that the isolated strains had good plant growth promoting effects on rice.

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