Delivery Systems for Introduction of Microbial Inoculants in the Field

Jambhulkar, Prashant P.; Sharma, Pratibha; Yadav, Rakesh

doi:10.1007/978-81-322-2644-4_13

Cited by 35 publications

(27 citation statements)

References 62 publications

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“…The latter technique is particularly relevant for the inoculation of perennial crops, where beneficial microorganisms need to be introduced into already established orchards or plantations (Malusá et al ., ). Furthermore, liquids permit the treatment of above‐ground plant parts, for example in form of a foliar spray (Jambhulkar et al ., ). This may be desirable if the active agent targets aerial plant parts (e.g.…”

Section: Introductionmentioning

confidence: 97%

Maintenance and assessment of cell viability in formulation of non‐sporulating bacterial inoculants

Berninger

López

Bejarano

et al. 2017

Microbial Biotechnology

153

106

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SummaryThe application of beneficial, plant‐associated microorganisms is a sustainable approach to improving crop performance in agriculture. However, microbial inoculants are often susceptible to prolonged periods of storage and deleterious environmental factors, which negatively impact their viability and ultimately limit efficacy in the field. This particularly concerns non‐sporulating bacteria. To overcome this challenge, the availability of protective formulations is crucial. Numerous parameters influence the viability of microbial cells, with drying procedures generally being among the most critical ones. Thus, technological advances to attenuate the desiccation stress imposed on living cells are key to successful formulation development. In this review, we discuss the core aspects important to consider when aiming at high cell viability of non‐sporulating bacteria to be applied as microbial inoculants in agriculture. We elaborate the suitability of commonly applied drying methods (freeze‐drying, vacuum‐drying, spray‐drying, fluidized bed‐drying, air‐drying) and potential measures to prevent cell damage from desiccation (externally applied protectants, stress pre‐conditioning, triggering of exopolysaccharide secretion, ‘helper’ strains). Furthermore, we point out methods for assessing bacterial viability, such as colony counting, spectrophotometry, microcalorimetry, flow cytometry and viability qPCR. Choosing appropriate technologies for maintenance of cell viability and evaluation thereof will render formulation development more efficient. This in turn will aid in utilizing the vast potential of promising, plant beneficial bacteria as sustainable alternatives to standard agrochemicals.

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Section: Introductionmentioning

confidence: 97%

Maintenance and assessment of cell viability in formulation of non‐sporulating bacterial inoculants

Berninger

López

Bejarano

et al. 2017

Microbial Biotechnology

153

106

View full text Add to dashboard Cite

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“…Multiple beneficial effects of soil microorganisms have widely been identified as key drivers for a better plant growth and increased soil P availability (Kumar, 2016;Peŕez et al, 2016;Bargaz et al, 2018). PGPR exhibiting high PSC have been described to benefit plant growth and yield when associated with roots and even within other plant parts such as leaves (Fahad et al, 2015;Jambhulkar et al, 2016;Tang et al, 2018). For example, application of efficient phosphate solubilizing bacteria (PSB) such as Bacillus megaterium increased soil P availability by nearly 30% (Alzoubi and Gaibore, 2012).…”

Section: Introductionmentioning

confidence: 99%

Phosphate Solubilizing Rhizobacteria Could Have a Stronger Influence on Wheat Root Traits and Aboveground Physiology Than Rhizosphere P Solubilization

et al. 2020

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Limited P availability in several agricultural areas is one of the key challenges facing current agriculture. Exploiting P-solubilizing bacteria (PSB) has been an emerging bio-solution for a higher rhizosphere P-availability, meanwhile the above-and below-ground interactions that PSB would trigger remain unclear over plant growing stages. We hypothesized that PSB effects on plant growth may be greater on root traits that positively links with aboveground physiology more than the commonly believed rhizosphere P bio-solubilization. In this study, five contrasting PSB (Pseudomonas spp.) isolates (low "PSB 1 ", moderate "PSB 2 and PSB 4 " and high "PSB 3 and PSB 5 " P-solubilizing capacity "PSC") were used to investigate aboveand below-ground responses in wheat fertilized with rock P (RP) under controlled conditions. Our findings show that all PSB isolates increased wheat root traits, particularly PSB 5 which increased root biomass and PSB 3 that had greater effect on root diameter in 7-, 15-and 42day old plants. The length, surface and volume of roots significantly increased along with higher rhizosphere available P in 15-and 42-day old plants inoculated with PSB 4 and PSB 2. Shoot biomass significantly increased with both PSB 2 and PSB 5. Root and shoot physiology significantly improved with PSB 1 (lowest PSC) and PSB 4 (moderate PSC), notably shoot total P (78.38%) and root phosphatase activity (390%). Moreover, nutrients acquisition and chlorophyll content increased in inoculated plants and was stimulated (PSB 2 , PSB 4) more than rhizosphere P-solubilization, which was also revealed by the significant above-and below-ground inter-correlations, mainly chlorophyll and both total (R = 0.75, p = 0.001**) and intracellular (R = 0.7, p = 0.000114*) P contents. These findings demonstrate the necessity to timely monitor the plant-rhizosphere continuum responses, which may be a relevant approach to accurately evaluate PSB through considering below-and above-ground relationships; thus enabling unbiased interpretations prior to field applications.

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“…However, microbial suspensions can damage or clog machinery by settling out of solution, and stresses caused by passage through spraying apparatus (such as heat stress or shearing forces) can decrease biocontrol strain viability [151]. Foliar spray is also typically used for microbial inoculants designed to counter foliar diseases [152], and so may be less apt for controlling root-diseases such as wheat take-all fungus. Soil inoculation is another recommended mode of application, typically used if biocontrol strains are particularly vulnerable to desiccation [152].…”

Section: The Potential Of Streptomyces Bacteria As Efficient Biocomentioning

confidence: 99%

“…Foliar spray is also typically used for microbial inoculants designed to counter foliar diseases [152], and so may be less apt for controlling root-diseases such as wheat take-all fungus. Soil inoculation is another recommended mode of application, typically used if biocontrol strains are particularly vulnerable to desiccation [152]. As discussed previously, methods such as bio-organic fertiliser application [139,141,143,144] and strain pre-establishment [106] can increase biocontrol success when using this method.…”

Section: The Potential Of Streptomyces Bacteria As Efficient Biocomentioning

confidence: 99%

Biocontrol of Cereal Crop Diseases Using Streptomycetes

et al. 2019

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A growing world population and an increasing demand for greater food production requires that crop losses caused by pests and diseases are dramatically reduced. Concurrently, sustainability targets mean that alternatives to chemical pesticides are becoming increasingly desirable. Bacteria in the plant root microbiome can protect their plant host against pests and pathogenic infection. In particular, Streptomyces species are well-known to produce a range of secondary metabolites that can inhibit the growth of phytopathogens. Streptomyces are abundant in soils and are also enriched in the root microbiomes of many different plant species, including those grown as economically and nutritionally valuable cereal crops. In this review we discuss the potential of Streptomyces to protect against some of the most damaging cereal crop diseases, particularly those caused by fungal pathogens. We also explore factors that may improve the efficacy of these strains as biocontrol agents in situ, as well as the possibility of exploiting plant mechanisms, such as root exudation, that enable the recruitment of microbial species from the soil to the root microbiome. We argue that a greater understanding of these mechanisms may enable the development of protective plant root microbiomes with a greater abundance of beneficial bacteria, such as Streptomyces species.

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Delivery Systems for Introduction of Microbial Inoculants in the Field

Cited by 35 publications

References 62 publications

Maintenance and assessment of cell viability in formulation of non‐sporulating bacterial inoculants

Maintenance and assessment of cell viability in formulation of non‐sporulating bacterial inoculants

Phosphate Solubilizing Rhizobacteria Could Have a Stronger Influence on Wheat Root Traits and Aboveground Physiology Than Rhizosphere P Solubilization

Biocontrol of Cereal Crop Diseases Using Streptomycetes

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