From Lab to Farm: Elucidating the Beneficial Roles of Photosynthetic Bacteria in Sustainable Agriculture

Abstract

Photosynthetic bacteria (PSB) possess versatile metabolic abilities and are widely applied in environmental bioremediation, bioenergy production and agriculture. In this review, we summarize examples of purple non-sulfur bacteria (PNSB) through biofertilization, biostimulation and biocontrol mechanisms to promote plant growth. They include improvement of nutrient acquisition, production of phytohormones, induction of immune system responses, interaction with resident microbial community. It has also been reported that PNSB can produce an endogenous 5-aminolevulinic acid (5-ALA) to alleviate abiotic stress in plants. Under biotic stress, these bacteria can trigger induced systemic resistance (ISR) of plants against pathogens. The nutrient elements in soil are significantly increased by PNSB inoculation, thus improving fertility. We share experiences of researching and developing an elite PNSB inoculant (Rhodopseudomonas palustris PS3), including strategies for screening and verifying beneficial bacteria as well as the establishment of optimal fermentation and formulation processes for commercialization. The effectiveness of PS3 inoculants for various crops under field conditions, including conventional and organic farming, is presented. We also discuss the underlying plant growth-promoting mechanisms of this bacterium from both microbial and plant viewpoints. This review improves our understanding of the application of PNSB in sustainable crop production and could inspire the development of diverse inoculants to overcome the changes in agricultural environments created by climate change.

A photosynthetic bacterial inoculant exerts beneficial effects on the yield and quality of tomato and affects bacterial community structure in an organic field

“…The PS3 inoculation exhibited notable effects in improving several key agricultural traits of tomato fruits in this study (Figures 2, 3), including marketable fruit yield, vitamin C content, phenolic content, and lycopene concentration, etc. According to our previous studies, the presumed mechanisms include (1) biofertilization for increasing plant-available nutrients in soil and (2) biostimulation for stimulating plant nutrition use efficiency (reviewed by Lee et al, 2021a). In this study, PS3 inoculation enhanced the soil physicochemical traits and enzymatic activities in the organic field (Figure 4).…”

“…Rhodopseudomonas palustris is a photosynthetic bacterium that can be applied as a PGPR inoculant to improve crop yield and quality, as well as alleviate biotic and abiotic stress for crops (Sakarika et al, 2020;Lee et al, 2021a). The deduced plant growthpromoting mechanisms of the plant-associated beneficial bacterium R. palustris can be summarized as facilitating nutrient acquisition in the soil or rhizosphere (i.e., biofertilization), producing phytohormones (i.e., biostimulation), and inducing the immune system in plants (i.e., biocontrol; Lee et al, 2021a).…”

Exploitation of Plant Growth Promoting Bacteria for Sustainable Agriculture: Hierarchical Approach to Link Laboratory and Field Experiments

“…However, even in the case of microbial consortia, it is important to evaluate how the environmental stresses can affect the vitality of bioinoculants. To this aim, various parameters, including bioinoculants formulation and delivery, should be monitored [ 79 , 80 , 81 ]. The identification of the right procedure for inoculant formulation is crucial to provide stabilization and protection of consortia during transport, storage, and application.…”

Perspectives on Converting Keratin-Containing Wastes Into Biofertilizers for Sustainable Agriculture

“…The addition of organisms suitable for the growth of plants to keratin degradation product will result in a high-quality biofertilizer to provide nutrients for the growth of plant, sustain the microorganism in the soil and reduce the usage of pesticides ( Figure 5 ). The organisms used in conventional biofertilizers can be screened from the soil or purchased from commercial resources, which can be applied in keratin treatment or mixed with microbial-treated keratins to produce biofertilizers with multiple functions to contribute to the sustainable agriculture (Bano et al, 2021 ; Kumar et al, 2021 ; Lee et al, 2021 ; Rios-Galicia et al, 2021 ; Seenivasagan and Babalola, 2021 ).…”