Figure - available via license: Creative Commons Attribution 4.0 International
Content may be subject to copyright.
Source publication
On average less than 1% of the total phosphorous present in soils is available to plants, making phosphorous one of the most limiting macronutrients for crop productivity worldwide. The aim of this work was to isolate and select phosphate solubilizing bacteria (PSB) from the barley rhizosphere, which has other growth promoting traits and can increa...
Contexts in source publication
Context 1
... of phosphatase activities involved in P solubilization was carried out. Acidic and alkaline phosphatase activities were detected in all the PSB, although these activities varied among the isolates (Table 2). B. megaterium PSB1 exhibited higher levels of both acidic and alkaline phosphatase, with B. cereus PSB3 and P. eucrina showing moderate levels of both activities. ...Context 2
... PSB3 treatment) and 8.67, values obtained for both negative (supplemented with insoluble phosphate), and positive (supplemented regularly with soluble phosphate by irrigation) controls, although no significant differences were observed between treatments. Similarly, no significant differences were detected either for the spike number per pot, with values ranging from 10.67 (negative control) to 11.78 (positive control) (Supplementary information; Table S2). Once the plants had completed their growth cycle, they were uprooted ...Context 3
... PSB3 treatment) and 8.67, values obtained for both negative (supplemented with insoluble phosphate), and positive (supplemented regularly with soluble phosphate by irrigation) controls, although no significant differences were observed between treatments. Similarly, no significant differences were detected either for the spike number per pot, with values ranging from 10.67 (negative control) to 11.78 (positive control) (Supplementary information; Table S2). Once the plants had completed their growth cycle, they were uprooted and dry weight and phosphate content of their root systems were determined. ...Context 4
... the plants had completed their growth cycle, they were uprooted and dry weight and phosphate content of their root systems were determined. Again, no significant differences were observed for both parameters (Table S2). ...Similar publications
As the awareness on the ecological impact of chemical phosphate fertilizers grows, research turns to sustainable alternatives such as the implementation of phosphate solubilizing bacteria (PSB), which make largely immobile phosphorous reserves in soils available for uptake by plants. In this review, we introduce the mechanisms by which plants facil...
Citations
... Barley is another crop that has shown positive effects following inoculation with P. fungorum (Ibáñez et al. 2021). The inoculation of barley seeds with strain PSB7, isolated from the barley rhizosphere, resulted in better phosphate accumulation in stems, greater dry weight, height of the aerial parts, and faster maturation of ears (Ibáñez et al. 2021). ...
... Barley is another crop that has shown positive effects following inoculation with P. fungorum (Ibáñez et al. 2021). The inoculation of barley seeds with strain PSB7, isolated from the barley rhizosphere, resulted in better phosphate accumulation in stems, greater dry weight, height of the aerial parts, and faster maturation of ears (Ibáñez et al. 2021). Direct PGP features of the strain were observed in vitro, including phosphate, zinc, and potassium solubilization and the production of siderophores, HCN, and IAA. ...
... Direct PGP features of the strain were observed in vitro, including phosphate, zinc, and potassium solubilization and the production of siderophores, HCN, and IAA. Inhibition of the plant pathogens Botrytis cinerea, F. oxysporum, Nigrospora oryzae, R. solani, and Alternaria alternata has also been identified for the strain PSB7 in agar plates (Ibáñez et al. 2021). However, there is no evidence of biocontrol in plants. ...
Agrochemicals are the primary alternative for maintaining the high yields necessary to produce sufficient plant-based foods to supply the world population. In recent decades, one of the most extensively explored alternatives to replace agrochemicals and reduce their environmental impact has been the use of microorganism-based products to boost crop yields with less environmental impact. This review focuses on the results of studies that have demonstrated the potential of the genus Paraburkholderia to increase crop yields and be utilized in biofertilizers and biocontrol products. A literature search was performed electronically considering articles and books published until August 19, 2024. We identified 24 species of Paraburkholderia with the ability to improve crop yields after their inoculation by different methods on seeds, seedlings, plantlets, adult crops, or fruits. The effects of these bacteria have been tested under laboratory, greenhouse, or field conditions. These Paraburkholderia species mediate their positive impact on crop growth by direct and indirect plant growth-promoting mechanisms, which include improving nutrient uptake, stimulating growth by phytohormone production, regulation and stimulation of metabolic pathways, induction of abiotic stress tolerance, and disease control by direct pathogen inhibition or induction of systemic resistance in plants. The literature reviewed here supports the use of Paraburkholderia in bio-inputs under the actual panorama of climate change and the necessity to increase sustainable agriculture worldwide.
... Is the world's fourth most extensively grown cereal, following wheat, rice, and corn. Around 70% of barley produced worldwide is utilized directly or indirectly for animal feed, with the remaining portion being used for malting and beer manufacture [16,17]. Compared to other cereal crops, barley is distinguished by its capacity to thrive in challenging environmental circumstances such salt and drought [18]. ...
Phosphorus is a vital element for all life forms. Phosphate-solubilizing bacteria transform phosphate into a bioavailable form through solubilization and mineralization processes. The aim of this study is evaluating the role of halotolerant, phosphate-solubilizing bacteria (PSB). having different PGPR traits as biofertilizers. Thirteen bacterial strains were isolated from soil samples of Ras Muhammad mangrove forest and screened for production of different PGPR traits. The most potent microbial Original Research Article Mussa et al.; Asian Soil Res. 125 candidates were identified by rRNA gene sequencing analysis and uploaded in GenBank as Bacillus safensis [OR341132] and Cytobacillus firmus [OR431197] these showed ability to tolerate salt concentration up to 10%, can fix nitrogen by growing on nitrogen free media with excellent growth and characterized qualitatively and quantitative solubilize phosphorous more than 100µg/ml of insoluble phosphate, hydrolyse phytate and produced IAA showing the highest value in the range of 94.54, 220,38 μg/mL respectively. In pot trials performed in a greenhouse the isolated strains Bacillus safensis [OR341132] and Cytobacillus firmus [OR431197] were able to significantly improve levels of assimilated phosphate, compared to non-inoculated plants. Moreover, mixed treatment (Bacillus safensis +Cytobacillus firmus) increased soil fertility and consequently improve the growth of parley plant. The study has overall concluded that bacteria isolated from mangrove soil, Bacillus safensis [OR341132] and Cytobacillus firmus [OR431197] could be used as the halotolerant plant growth-promoting rhizobacteria [HT-PGPR] and phosphate-solubilizing bacteria [PSB] and have a good influence on the health of barley [genotype Giza123] plants under salinity conditions during thirty days.
... These plates were incubated at 28 • C for 3 days and the relative bacterial colonies were selected based on the appearance of hyaline circles (Valetti et al., 2018). The isolates were subjected to successive purification steps and the purified strain was then stored in glycerol stock at −80 • C. The solubility index (SI) was determined by measuring hyaline circles and colony diameters at 4 days of culture according to the following formula: SI = (colony diameter + halo diameter)/(colony diameter) (Ibáñez et al., 2021). ...
Background
Plant growth-promoting rhizobacteria (PGPR) are an integral part of agricultural practices due to their roles in promoting plant growth, improving soil conditions, and suppressing diseases. However, researches on the PGPR in the rhizosphere of carrots, an important vegetable crop, is relative limited. Therefore, this study aimed to isolate and characterize PGPR strains from the rhizosphere soil of greenhouse-grown carrots, with a focus on their potential to stimulate carrot growth.
Methods
Through a screening process, 12 high-efficiency phosphorus-solubilizing bacteria, one nitrogen-fixing strain, and two potassium-solubilizing strains were screened. Prominent among these were Bacillus firmus MN3 for nitrogen fixation ability, Acinetobacter pittii MP41 for phosphate solubilization, and Bacillus subtilis PK9 for potassium-solubilization. These strains were used to formulate a combined microbial consortium, N3P41K9, for inoculation and further analysis.
Results
The application of N3P41K9, significantly enhanced carrot growth, with an increase in plant height by 17.1% and root length by 54.5% in a pot experiment, compared to the control group. This treatment also elevated alkaline-hydrolyzable nitrogen levels by 72.4%, available phosphorus by 48.2%, and available potassium by 23.7%. Subsequent field trials confirmed the efficacy of N3P41K9, with a notable 12.5% increase in carrot yields. The N3P41K9 treatment had a minimal disturbance on soil bacterial diversity and abundance, but significantly increased the prevalence of beneficial genera such as Gemmatimonas and Nitrospira. Genus-level redundancy analysis indicated that the pH and alkali-hydrolyzable nitrogen content were pivotal in shaping the bacterial community composition.
Discussion
The findings of this study highlight the feasibility of combined microbial consortium in promoting carrot growth, increasing yield, and enriching the root environment with beneficial microbes. Furthermore, these results suggest the potential of the N3P41K9 consortium for soil amelioration, offering a promising strategy for sustainable agricultural practices.
... Consequently, they release phosphorus into the soil by means of their capacity to solubilize organic and inorganic phosphorus. Previous research has shown that the rhizosphere contains a substantially higher population of phosphate solubilizing bacteria than non-rhizospheric soil (Linu et al., 2019;Ibáñez et al., 2021). Moreover, According to Anand et al. (2016), phosphorus solubilizing bacteria (PSB) are more efficient than fungal species in the solubilization of phosphorus, and make up 1-50% of the total microbial population in soil. ...
Phosphate-solubilizing bacteria, which are among the plant growth-promoting bacteria, dissolve insoluble phosphate in the soil by several pathways and promote plant growth. Therefore, it offers an alternative option instead of applying chemical fertilizers that disrupt soil chemistry and ecological balance. Although research on phosphate solubilizing bacteria has increased recently, the research on the peppermint and fennel rhizosphere is still limited. Investigating different rhizospheric local bacteria that can solubilize phosphate and replace chemical fertilizers is necessary. It was determined that 15 of the 53 bacterial isolates obtained from peppermint (Mentha piperita L.) and fennel (Foeniculum vulgare L.) rhizospheres formed a transparent (halo) region around the colonies on Pikovskaya Agar (PKA) medium using the MALDI-TOF MS method. The morphological, biochemical and IAA production of these isolates as well as quantitative measurements of phosphate solubilization by the isolates in NBRIP broth medium was evaluated. The highest efficiency was noted from Bacillus subtilis MMS-7 with solubilization value of 281.6 mg L-1. This was followed by Pseudomonas fluorescens MMS-11 with solubilization value of 263.4 mg L-1 and Bacillus thuringiensis MMS-3 with solubilization value of 172.1 mg L-1, respectively. Among the Phosphate solubilizing bacterial isolates, P solubilization index ranged 1.2-3.7 on PKA agar medium. Additionally, the highest IAA production was noted at 23.38 µg ml-1, using Bacillus subtilis MMS-7. This was followed by Pseudomonas fluorescens MMS-11 with value of 19.72 µg ml-1 and Bacillus thuringiensis using MMS-3 with value of 18.98 µg ml-1. This study demonstrated that selected local isolates can be used as effective phosphate-based microbial fertilizers.
... Serving as microbial inoculants, biofertilizers enhance soil physicochemical properties, microbial community diversity, and plant growth [3]. Useful microbial populations in agriculture include plant growth-promoting rhizobacteria (PGPR), N 2 -fixing cyanobacteria, plant disease-suppressive bacteria, oil-toxicant degrading microbes, and actinomycetes [4,5]. ...
... Although some studies have examined the effects on soil microorganisms, few have specifically investigated the rhizosphere microenvironment [20][21][22][23][24]. Therefore, further studies are necessary to investigate the responses of rhizosphere microbial communities in the coexistence of biofertilizers and MPs and enhance our understanding of the impact on the rhizosphere environment. For conventional MPs, MPs can change the features of soil (e.g., pH value, water evaporation, and aggregate stability) [5,25], microbial profiles (e.g., diversity, composition, and organic matter metabolic ability) [26], and the physicochemical properties of crops (e.g., biomass, growth, and root development) [2]. The interaction between Bio-MPs and biofertilizers and their impact on soil microecological characteristics are relatively unknown compared with conventional plastic particles. ...
Biodegradable microplastics (Bio-MPs) are a hot topic in soil research due to their potential to replace conventional microplastics. Biofertilizers are viewed as an alternative to inorganic fertilizers in agriculture due to their potential to enhance crop yields and food safety. The use of both can have direct and indirect effects on rhizosphere microorganisms. However, the influence of the coexistence of “Bio-MPs and biofertilizers” on rhizosphere microbial characteristics remains unclear. We investigated the effects of coexisting biofertilizers and Bio-MPs on the structure, function, and especially the carbon metabolic properties of crop rhizosphere bacteria, using a pot experiment in which polyethylene microplastics (PE-MPs) were used as a reference. The results showed that the existence of both microplastics (MPs) changed the physicochemical properties of the rhizosphere soil. Exposure to MPs also remarkably changed the composition and diversity of rhizosphere bacteria. The network was more complex in the Bio-MPs group. Additionally, metagenomic analyses showed that PE-MPs mainly affected microbial vitamin metabolism. Bio-MPs primarily changed the pathways related to carbon metabolism, such as causing declined carbon fixation/degradation and inhibition of methanogenesis. After partial least squares path model (PLS-PM) analysis, we observed that both materials influenced the rhizosphere environment through the bacterial communities and functions. Despite the degradability of Bio-MPs, our findings confirmed that the coexistence of biofertilizers and Bio-MPs affected the fertility of the rhizosphere. Regardless of the type of plastic, its use in soil requires an objective and scientifically grounded approach.
... In a study by Ibáñez et al. (2021), among 104 isolates obtained from the rhizospheres of the barley plant, Stenotrophomonas sp (AJK-9) and S. rhizophila (AJK-3) showed the maximum IAA (77.98 µg ml −1 , 72.32 µg ml −1 ) produced. Similarly, in our study, MH-54-4 (Stenotrophomonas sp.) also produced IAA (Table 4). ...
... Numerous studies have reported that the use of phosphate-solubilizing bacteria (PSBs) can increase the productivity of many different annual crops, such as barley, canola, maize, peanut, potato, sesame, sorghum, soybean, and wheat, among others [11,21,22,[24][25][26][27][28][29], as previously indicated in Section 1. However, to our knowledge, no data regarding the use of PSBs in perennial crops has been reported. ...
... The isolation of PSBs from the rhizosphere environment of hop plants indicated that 17.82% of the isolates could solubilize phosphate in solid NBRIP medium. This value was, however, considerably lower than the value of 61.5% of PSBs isolated from the rhizosphere of barley plants [21], which might suggest that the capability of different vegetable species to recruit PSBs to their rhizosphere could be different. The characterization of the 5 best phosphate solubilizers in solid NBRIP medium indicated that 4 of them (isolates ULE-PH1, ULE-PH5, ULE-PH6, and ULE-PH12) belonged to the Pseudomonas genus, whereas 1 belonged to the Bacillus genus (isolate ULE-PH10). ...
... The characterization of the 5 best phosphate solubilizers in solid NBRIP medium indicated that 4 of them (isolates ULE-PH1, ULE-PH5, ULE-PH6, and ULE-PH12) belonged to the Pseudomonas genus, whereas 1 belonged to the Bacillus genus (isolate ULE-PH10). Pseudomonas species were also the most frequently isolated PSBs from the rhizosphere of barley plants (9 out of the 17; 52.94%) [21], and the rhizosphere of shisham plants (7 out of 18 isolates; 38.89%) [49]. They were also dominant [50]. ...
Most of the phosphorus incorporated into agricultural soils through the use of fertilizers precipitates in the form of insoluble salts that are incapable of being used by plants. This insoluble phosphorus present in large quantities in soil forms the well-known “phosphorus legacy”. The solubilization of this “phosphorus legacy” has become a goal of great agronomic importance, and the use of phosphate-solubilizing bacteria would be a useful tool for this purpose. In this work, we have isolated and characterized phosphate-solubilizing bacteria from the rhizosphere of hop plants. Two particular strains, Pseudomonas taetrolens ULE-PH5 and Pseudomonas sp. ULE-PH6, were selected as plant growth-promoting rhizobacteria due to their high phosphate solubilization capability in both plate and liquid culture assays and other interesting traits, including auxin and siderophore production, phytate degradation, and acidic and alkaline phosphatase production. These strains were able to significantly increase phosphate uptake and accumulation of phosphorus in the aerial part (stems, petioles, and leaves) of hop plants, as determined by greenhouse trials. These strains are promising candidates to produce biofertilizers specifically to increase phosphate adsorption by hop plants.
... Another type of bacteria, namely Bacillus cereus, was shown to produce Indole Acetic Acid (IAA) (Zhou et al., 2021). The formation of a clear zone on National Botanical Research Institute's Phosphate (NBRIP) media around the colony is also an indication of the activity of phosphate-solubilizing bacteria (Ibáñez et al., 2021). Another collection, namely B. cereus RC76, the results of the in vitro antagonism test of isolates against Ralstonia syzygii subsp. ...
Shallot (Allium cepa var. aggregatum.) is a horticultural plant that is widely consumed in the world. However, the productivity of shallots in Indonesia is still relatively low, if compared to the actual optimum production potential of shallot. Shallot cultivation in Indonesia often experiences many problems. One of the problems is twisted diseases caused by Fusarium sp. This research aimed to study the effect of the application of organic material enriched with Bacillus in suppressing the development of twisted disease of shallot. This study was arranged in Randomized Complete Block Design (RCBD) with 5 treatments namely (A) compost + Bacillus velezensis isolate B-27, (B) compost + Bacillus cereus isolate RC76, (C) B. velezensis isolate B-27+B. cereus isolate RC76+compost, (D) compost + Trichoderma asperellum and (E) control (compost 1 ton/ha) with 5 replications on glasshouse treatment and 3 replications on field treatment. The results showed that the combination of B. velezensis in compost effectively reduced the incidence of twisted disease, the number of Fusarium spp. colonies, and the number of infected bulbs by Fusarium sp. Besides, the combination of compost with microbial agents showed better results than compost single treatment.
... This process is carried out through several mechanisms, such as (i) the secretion of organic acids, (ii) the chelation of cations like Ca 2+ , Al 3+ or Fe 3+ , or (iii) the release of enzymes such as phosphatases and phytases. Among the most extensively studied P solubilizers appears microorganisms belonging to the genera Pseudomonas, Bacillus, Rhizobium, Enterobacter, Penicillium, and Aspergillus [2,22,23,25]. ...
... Direct mechanisms encompass nitrogen fixation, phosphorus solubilization, and phytohormone production, whereas indirect methods include the production of several compounds such as siderophores, antibiotics, hydrogen cyanide, lytic enzymes, and similar bioactive substances that provide resistance to plant pathogens [24]. Within this group, in addition to the previously mentioned genera, other like Klebsiella spp., Serratia spp., Burkholderia spp., Streptomyces spp., Pantoea spp., or Trichoderma, are also observed (Table 1) [2,25]. Another important group of microorganisms concerning biofertilizers are the arbuscular mycorrhizal fungi (AM fungi), which represent a critical component of the soil microbiome by enhancing phosphorus uptake and water and nutrient absorption. ...
... Plant growth promotion; organic acid production; P and K solubilization; antifungal activity Barley [25] Astragalus mongholicus [35] Plant growth promotion Arabidopsis thaliana [38] Bacillus aryabhattai Improve tolerance to salt stress Oryzae sativa [39] Bacillus cereus ...
Nowadays, legal regulations and social environmental concerns are converging towards the promotion of more sustainable agriculture based on organic compounds and soil preservation. These trends are fuelling the growth of the biofertilizers, which are beneficial preparations containing microorganisms able to enhance a plant’s ability to uptake essential nutrients. Their production and commercialization encompass a multitude of critical steps deeply reviewed in this manuscript through an exhaustive overview of the key stages, such as microorganism selection, new environmental sources, upscaling to field trials, encapsulation, current application systems and regulatory considerations. However, although the economical expectations are promising, several methodological, environmental, and legal concerns are undermining their advancement. The redefinition of international legal frameworks, their enhancement based on trending technologies, and the fostering of multidisciplinary collaboration across sectors are key players to promote biofertilizers as eco-friendly and cost-effective alternatives to chemical fertilizers.
... In similar studies, as a result of Azospirillum + Azotobacter bacteria treatments and N-P treatments, maximum 1000-kernel weight, grain yield, biological yield and harvest index were obtained as compared to the Control treatments and a minimum was obtained from Control treatments [35]. In another study, it was stated that PGPR bacteria (especially Azospirillum) significantly increased grain yield, therefore it could be used instead of chemical fertilizers in sustainable agricultural systems [36][37][38][39][40]. Use of nitrogen-fixing bacteria Azotobacter and Azospirillum with 100 kg urea decreased nitrogen fertilizer demand up to 50% and increased 1000-kernel weight, nitrogen content and yield of barley [34]. ...
... Several of the isolated strains (Advenella mimigardefordensis, Bacillus cereus, Bacillus megaterium and Burkholderia fungorum) were able to significantly improve levels of assimilated phosphate, dry weight of ears and total starch accumulated on ears as compared to non-inoculated plants. Since these strains were able to increase the growth and productivity of barley crops, they could be potentially used as biofertilizers [40]. Endophyte populations of the inoculated bacteria were observed in plants growing under field conditions. ...