Long-term effect of inoculating lodgepole pine seedlings with plant growth-promoting bacteria originating from disturbed gravel mining ecosystem

Bacterial Strains ◽

Acetic Acid Production ◽

Gravel Mining ◽

Pine Seedlings ◽

Pine Trees

Gravel mining is prevalent in forest landscapes of Canada, typically resulting in complete loss of vegetation and topsoil. Despite such extreme disturbance, lodgepole pine (Pinus contorta var. latifolia) trees are thriving at unreclaimed gravel pits located in central-interior British Columbia, possibly due, at least in part, to the association of pine trees with their endophytic bacteria. Testing this possibility, several bacterial strains were previously isolated from pine trees growing at these pits, of which 14 were identified as effective nitrogen-fixers. In this study, we evaluated the inoculation effect of these 14 strains on lodgepole pine growth under nitrogen-poor conditions. Each strain colonized the rhizosphere and internal tissues of pine seedlings and significantly enhanced their length (24–65%) and biomass (100–300%), 18 months after sowing and inoculation. Notably, three Pseudomonas strains increased pine seedling length by 1.6-fold and biomass by 4-fold. Most strains also demonstrated substantial potential to promote plant growth via phosphorus solubilization, siderophore production, 1-aminocyclopropane-1-carboxylic acid deaminase activity, indole-3-acetic acid production, lytic enzyme activity and catalase activity. Our results suggest that such effective bacteria could be sustaining pine growth on bare gravel, indicating a possible ecological association that may explain natural tree regeneration in such a disturbed ecosystem.

Isolation and Molecular Characterization of Plant-Growth-Promoting Bacteria and Their Effect on Eggplant (Solanum melongena) Growth

Agriculture ◽

10.3390/agriculture11121258 ◽

2021 ◽

Vol 11 (12) ◽

pp. 1258

Author(s):

Xuqing Li ◽

Jianli Yan ◽

Dingyi Li ◽

Yugen Jiang ◽

Ya Zhang ◽

...

Keyword(s):

Plant Growth ◽

Solanum Melongena ◽

Housekeeping Genes ◽

Mountainous Area ◽

Bacterial Strains ◽

Reclaimed Land ◽

Acetic Acid Production ◽

Plant Growth Promoting ◽

In recent years, the optimum development of land resources has become an important task for ensuring the security of food production in China. Soil microorganisms have been considered to play an important role in conferring soil fertility and productivity. In order to obtain the plant-growth-promoting bacteria in newly reclaimed land, a total of 988 bacterial strains were isolated from nine soil samples collected from different sites in wastelands in Hangzhou (Zhejiang Province, China), a rural mountainous area. Among them, five strains exhibited substantial potential of phosphate solubilization, nitrogen fixation, siderophore production and indole acetic acid production at both pH 5.0 and pH 7.0, and also promoted eggplant growth in immature soil from newly reclaimed land. Furthermore, bacterial strains ZJ62 and ZJ3-12 were identified as Pantoeadispersa and Pantoea ananatis, respectively, while strains ZJ5, ZJ9 and ZJ174 were identified as Burkholderiaarboris, Burkholderia pyrrocinia and Burkholderia pyrrocinia, respectively, based on colony morphology observation and phylogenetic analysis of 16S rDNA and the housekeeping genes sequences. Overall, the result of this study showed that the 5 obtained bacterial strains have a great potential in promoting plant growth in immature soil from newly reclaimed land.

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 ◽

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.

The Effects of Plant Growth-Promoting Bacteria with Biostimulant Features on the Growth of a Local Onion Cultivar and a Commercial Zucchini Variety

Agronomy ◽

10.3390/agronomy11050888 ◽

2021 ◽

Vol 11 (5) ◽

pp. 888

Author(s):

Giorgia Novello ◽

Patrizia Cesaro ◽

Elisa Bona ◽

Nadia Massa ◽

Fabio Gosetti ◽

...

Keyword(s):

Plant Growth ◽

Growth Promotion ◽

Global Market ◽

Bacterial Strains ◽

Mineral Concentration ◽

Positive Effects ◽

Plant Growth Promoting ◽

Onion Cultivar ◽

The reduction of chemical inputs due to fertilizer and pesticide applications is a target shared both by farmers and consumers in order to minimize the side effects for human and environmental health. Among the possible strategies, the use of biostimulants has become increasingly important as demonstrated by the fast growth of their global market and by the increased rate of registration of new products. In this work, we assessed the effects of five bacterial strains (Pseudomonas fluorescens Pf4, P. putida S1Pf1, P. protegens Pf7, P. migulae 8R6, and Pseudomonas sp. 5Vm1K), which were chosen according to their previously reported plant growth promotion traits and their positive effects on fruit/seed nutrient contents, on a local onion cultivar and on zucchini. The possible variations induced by the inoculation with the bacterial strains on the onion nutritional components were also evaluated. Inoculation resulted in significant growth stimulation and improvement of the mineral concentration of the onion bulb, induced particularly by 5Vm1K and S1Pf1, and in different effects on the flowering of the zucchini plants according to the bacterial strain. The present study provides new information regarding the activity of the five plant growth-promoting bacteria (PGPB) strains on onion and zucchini, two plant species rarely considered by the scientific literature despite their economic relevance.

Phytostabilization of Polluted Military Soil Supported by Bioaugmentation with PGP-Trace Element Tolerant Bacteria Isolated from Helianthus petiolaris

Agronomy ◽

10.3390/agronomy10020204 ◽

2020 ◽

Vol 10 (2) ◽

pp. 204 ◽

Cited By ~ 4

Author(s):

Anabel Saran ◽

Valeria Imperato ◽

Lucia Fernandez ◽

Panos Gkorezis ◽

Jan d’Haen ◽

...

Keyword(s):

Plant Growth ◽

Trace Element ◽

Animal Health ◽

Environmental Pollutants ◽

Polluted Soil ◽

Bacterial Strains ◽

Plant Parts ◽

Trace Element Mobility ◽

Helianthus Petiolaris

Lead (Pb) and cadmium (Cd) are major environmental pollutants, and the accumulation of these elements in soils and plants is of great concern in agricultural production due to their toxic effects on crop growth. Also, these elements can enter into the food chain and severely affect human and animal health. Bioaugmentation with plant growth-promoting bacteria (PGPB) can contribute to an environmentally friendly and effective remediation approach by improving plant survival and promoting element phytostabilization or extraction under such harsh conditions. We isolated and characterised Pb and Cd-tolerant root-associated bacteria from Helianthus petiolaris growing on a Pb/Cd polluted soil in order to compose inoculants that can promote plant growth and also ameliorate the phytostabilization or phytoextraction efficiency. One hundred and five trace element-tolerant rhizospheric and endophytic bacterial strains belonging to eight different genera were isolated from the aromatic plant species Helianthus petiolaris. Most of the strains showed multiple PGP-capabilities, ability to immobilise trace elements on their cell wall, and promotion of seed germination. Bacillus paramycoides ST9, Bacillus wiedmannii ST29, Bacillus proteolyticus ST89, Brevibacterium frigoritolerans ST30, Cellulosimicrobium cellulans ST54 and Methylobacterium sp. ST85 were selected to perform bioaugmentation assays in greenhouse microcosms. After 2 months, seedlings of sunflower (H. annuus) grown on polluted soil and inoculated with B. proteolyticus ST89 produced 40% more biomass compared to the non-inoculated control plants and accumulated 20 % less Pb and 40% less Cd in the aboveground plant parts. In contrast, B. paramycoides ST9 increased the bioaccumulation factor (BAF) of Pb three times and of Cd six times without inhibiting plant growth. Our results indicate that, depending on the strain, bioaugmentation with specific beneficial bacteria can improve plant growth and either reduce trace element mobility or enhance plant trace element uptake.

Endophytic nitrogen fixation – a possible ‘hidden’ source of nitrogen for lodgepole pine trees growing at unreclaimed gravel mining sites

FEMS Microbiology Ecology ◽

10.1093/femsec/fiz172 ◽

2019 ◽

Vol 95 (11) ◽

Cited By ~ 8

Author(s):

Kiran Preet Padda ◽

Akshit Puri ◽

Chris Chanway

Keyword(s):

Nitrogen Fixation ◽

Lodgepole Pine ◽

Nifh Gene ◽

Control Treatment ◽

Nitrogen Fixing ◽

Nitrogen Fixing Bacteria ◽

Mining Sites ◽

Greenhouse Study ◽

Gravel Mining ◽

Pine Trees

ABSTRACT Lodgepole pine (Pinus contorta var. latifolia) trees have been thriving on unreclaimed gravel mining sites in British Columbia, Canada, with tissue nitrogen-content and growth-rate unaffected by extremely low soil nitrogen-levels. This indicates that pine trees could be accessing a hidden nitrogen source to fulfill their nitrogen requirements – possibly via endophytic nitrogen-fixation. Endophytic bacteria originally isolated from native pine trees growing at gravel sites were selected (n = 14) for in vitro nitrogen-fixation assays and a year long greenhouse study to test the overall hypothesis that naturally occurring endophytic nitrogen-fixing bacteria sustain pine tree growth under nitrogen-limited conditions. Each of the 14 bacteria colonized the internal tissues of pine trees in the greenhouse study and fixed significant amounts of nitrogen from atmosphere (23%–53%) after one year as estimated through 15N isotope dilution assay. Bacterial inoculation also significantly enhanced the length (31%–64%) and biomass (100%–311%) of pine seedlings as compared to the non-inoculated control treatment. In addition, presence of the nifH gene was confirmed in all 14 bacteria. Our results support the possibility that pine trees associate with nitrogen-fixing bacteria, capable of endophytic colonization, to survive at unreclaimed gravel mining pits and this association could potentially be utilized for effective reclamation of highly disturbed sites in a sustainable manner.

Growth response of wheat cultivars to bacterial inoculation in calcareous soil

Plant Soil and Environment ◽

10.17221/75/2010-pse ◽

2010 ◽

Vol 56 (No. 12) ◽

pp. 570-573 ◽

Cited By ~ 14

Author(s):

D. Egamberdieva

Keyword(s):

Plant Growth ◽

Calcareous Soil ◽

Dry Weight ◽

Wheat Cultivars ◽

Bacterial Strains ◽

Bacterial Inoculation ◽

Plant Growth Promoting ◽

Growth Promoting ◽

Selection Of

In this study the plant growth-promoting bacteria were analysed for their growth-stimulating effects on two wheat cultivars. The investigations were carried out in pot experiments using calcareous soil. The results showed that bacterial strains Pseudomonas spp. NUU1 and P. fluorescens NUU2 were able to colonize the rhizosphere of both wheat cultivars. Their plant growth-stimulating abilities were affected by wheat cultivars. The bacterial strains Pseudomonas sp. NUU1 and P. fluorescens NUU2 significantly stimulated the shoot and root length and dry weight of wheat cv. Turon, whereas cv. Residence was less affected by bacterial inoculation. The results of our study suggest that inoculation of wheat with Pseudomonas strains can improve plant growth in calcareous soil and it depends upon wheat cultivars. Prior to a selection of good bacterial inoculants, it is recommended to select cultivars that benefit from association with these bacteria.

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 ◽

Bacterial Strains ◽

Soil Release ◽

Plant 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.

Plant growth promotion of barley (Hordeum vulgare L.) by potassium solubilizing bacteria with multifarious plant growth promoting attributes

Plant Science Today ◽

10.14719/pst.1377 ◽

2021 ◽

Vol 8 (sp1) ◽

pp. 17-24

Author(s):

Tanvir Kaur ◽

Rubee Devi ◽

Divjot Kour ◽

Ashok Yadav ◽

Ajar Nath Yadav

Keyword(s):

Plant Growth ◽

Environmental Sustainability ◽

Growth Promotion ◽

Growth Parameters ◽

Sugar Content ◽

Bacterial Strains ◽

Hordeum Vulgare L ◽

Plant Growth Promoting ◽

Potassium (K) is the foremost macronutrients for growth of plant, soil health and fertility. The huge application of NPK chemical fertilizers negatively impacts the economy and is a threat to environmental sustainability. The rapid depletion of K mineral in soil is due to the application of agrochemicals agricultural fields for the production of crops in India. In present investigation, K-solubilizing microbes (KSM) were isolated and enumerated from cereal crops growing in Sirmour Himachal Pradesh. A total 125 bacteria were isolated and screened for K- solubilization on Aleksandrov agar plates and found that 31 bacterial strains exhibited K-solubilization. These 31 K-solubilizing strains of bacteria were additionally screened for other plant growth promoting (PGP) potential including solubilization of minerals, production of siderophores, ammonia, hydrogen cyanide and indole acetic acids. The performance of an efficient K-solubilizer was evaluated for plant growth promoting ability in pot assay under in vitro conditions. The strain EU-LWNA-25 positively influenced shoot length, fresh weight, carotenoids and total sugar content than the full dose, half dose and control. The strain enhancing physiological and growth parameters was identified by BLASTn analysis as Pseudomonas gessardii EU-LWNA-25. K-solubilizing plant growth promoting bacteria could be suitable bioinoculants for Rabi seasonal crops and overcomes the challenges of sustainable agriculture in K-deficient soil.

Isolation and Identification of Endophytic Bacteria from Mycorrhizal Tissues of Terrestrial Orchids from Southern Chile

Diversity ◽

10.3390/d12020055 ◽

2020 ◽

Vol 12 (2) ◽

pp. 55 ◽

Cited By ~ 3

Author(s):

Héctor Herrera ◽

Tedy Sanhueza ◽

Alžběta Novotná ◽

Trevor C. Charles ◽

Cesar Arriagada

Keyword(s):

Plant Growth ◽

Endophytic Bacteria ◽

Developmental Stages ◽

Pathogenic Fungi ◽

Southern Chile ◽

Bacterial Strains ◽

Isolation And Identification ◽

Acetic Acid Production ◽

Terrestrial Orchids ◽

Plant Growth Promoting

Endophytic bacteria are relevant symbionts that contribute to plant growth and development. However, the diversity of bacteria associated with the roots of terrestrial orchids colonizing Andean ecosystems is limited. This study identifies and examines the capabilities of endophytic bacteria associated with peloton-containing roots of six terrestrial orchid species from southern Chile. To achieve our goals, we placed superficially disinfected root fragments harboring pelotons on oatmeal agar (OMA) with no antibiotic addition and cultured them until the bacteria appeared. Subsequently, they were purified and identified using molecular tools and examined for plant growth metabolites production and antifungal activity. In total, 168 bacterial strains were isolated and assigned to 8 OTUs. The orders Pseudomonadales, Burkholderiales, and Xanthomonadales of phylum Proteobacteria were the most frequent. The orders Bacillales and Flavobacteriales of the phylla Firmicutes and Bacteroidetes were also obtained. Phosphate solubilization was detected in majority of isolates; however, it was significantly higher in Collimonas pratensis and Chryseobacterium sp. (PSI = 1.505 ± 0.09 and 1.405 ± 0.24, respectively). Siderophore production was recorded only for C. pratensis (0.657 ± 0.14 mm day−1), Dyella marensis (0.131 ± 0.02 mm day−1), and Luteibacter rhizovicinus (0.343 ± 0.12 mm day−1). Indole acetic acid production was highly influenced by the isolate identity; however, the significantly higher activity was recorded for Pseudomonas spp. (ranging from 5.507 ± 1.57 µg mL−1 to 7.437 ± 0.99 µg mL−1). Additionally, six bacterial isolates were able to inhibit the growth of some potential plant pathogenic fungi. Our findings demonstrate the potential for plant growth promoting capabilities and some antifungal activities of endophytic bacteria inhabiting the mycorrhizal tissue of terrestrial orchids, which may contribute especially at early developmental stages of orchid seedlings.