Is the Application of Plant Probiotic Bacterial Consortia Always Beneficial for Plants? Exploring Synergies between Rhizobial and Non-Rhizobial Bacteria and Their Effects on Agro-Economically Valuable Crops

Abstract

The overgrowth of human population and the demand for high-quality foods necessitate the search for sustainable alternatives to increase crop production. The use of biofertilizers, mostly based on plant probiotic bacteria (PPB), represents a reliable and eco-friendly solution. This heterogeneous group of bacteria possesses many features with positive effects on plants; however, how these bacteria with each other and with the environment when released into a field has still barely been studied. In this review, we focused on the diversity of root endophytic rhizobial and non-rhizobial bacteria existing within plant root tissues, and also on their potential applications as consortia exerting benefits for plants and the environment. We demonstrated the benefits of using bacterial inoculant consortia instead of single-strain inoculants. We then critically discussed several considerations that farmers, companies, governments, and the scientific community should take into account when a biofertilizer based on those PPBs is proposed, including (i) a proper taxonomic identification, (ii) the characterization of the beneficial features of PPB strains, and (iii) the ecological impacts on plants, environment, and plant/soil microbiomes. Overall, the success of a PPB consortium depends on many factors that must be considered and analyzed before its application as a biofertilizer in an agricultural system.

Microbial Diversity of Psychrotolerant Bacteria Isolated from Wild Flora of Andes Mountains and Patagonia of Chile towards the Selection of Plant Growth-Promoting Bacterial Consortia to Alleviate Cold Stress in Plants

“…In the present study, Pseudomonas and Stenotrophomonas genera showed the highest number of psychrotolerant strains, with 18 and 17 isolates, respectively (Figure 2). Strains of the Pseudomonas genus were isolated in the rhizosphere (16) and the phyllosphere (2). Stenotrophomonas strains genus were also isolated from the rhizosphere (12) and the phyllosphere (5).…”

“…The search for psychrotolerant PGPB that can exert their role of plant growth-promoting at low temperatures is of high importance for agriculture [12,105,106]. The benefits of mixed PGPB inoculation are due to the combination of plant growth-promoting (PGP) activities [16]. In this context, for the selection of a group of psychrotolerant bacterial consortia, different PGP activities were evaluated in the 70 selected psychrotolerant strains (Figure 3, Table 3).…”

“…The identification of PGPB that retain their potential to promote plant growth at low temperatures, is a worldwide trend in the field of agricultural inoculation technology [ 13 , 14 ]. On the other hand, the formulation of bacterial consortia (≥2 compatible bacteria) can increase the efficiency of agricultural crop production particularly under challenging environmental conditions, due to exploitation of their complementary and synergistic characteristics, compared to a single bacterium [ 15 , 16 ]. Various studies report plant growth-promoting effects with the application of a single bacterium, such as Pseudomonas , Bacillus , Serratia , Pantoea , and Paraburkholderia strains on canola, wheat, grapevine, and tomato under cold stress [ 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 ].…”

Diversidade, mecanismos de atuação e potencial agrícola de bactérias promotoras de crescimento de plantas, usando milho como cultura exemplo

“…Várias bactérias, tais como Azospirillum (MONTAÑEZ et al, 2009), Klebsiella (ARRUDA et al, 2013), Burkholderia (CHELIUS; TRIPLETT, 2001), Bacillus (BOMFIM et al, 2020) e Pseudomonas (PIROMYOU et al, 2011), têm sido identificadas como BPCP para milho por meio da fixação biológica de nitrogênio (FBN), solubilização de fosfato, produção de fitormônio e controle biológico de patógenos no solo. Tem sido relatado que a FBN pelas BPCP contribui com até 12-70% da absorção total de N em cultivo no campo ou 26,7 kg N ha −1 (70% da absorção total de N) em milho (MONTAÑEZ et al, 2009), bem como aumento na captação de fósforo como resultado da inoculação MAKUMBA; MBEGA, 2019; HASHEM; TABASSUM; FATHI ABD_ALLAH, 2019;SAXENA et al, 2019;MENÉNDEZ;PAÇO, 2020;TORRES et al, 2020).…”

Bioremediation by Cupriavidus metallidurans Strain MSR33 of Mercury-Polluted Agricultural Soil in a Rotary Drum Bioreactor and Its Effects on Nitrogen Cycle Microorganisms

“…In agricultural soils, nitrogen-fixing bacteria is an indicator of soil quality [ 7 , 9 ]. Nitrogen-fixing microorganisms contribute to plants productivity and are essential in agricultural systems [ 6 , 10 , 11 ]. Nitrification is performed by bacteria and archaea, which oxidize ammonia to nitrite and nitrate [ 2 , 8 ].…”