Disclosure of exact protocols of fermentation, identity of microorganisms within consortia, formation of advanced consortia with microbe-based products

Trends in Soil Microbial Inoculants Research: A Science Mapping Approach to Unravel Strengths and Weaknesses of Their Application

“…In the last decades, soil microbes have shown great potential for plant nutrition and protection applications in agriculture, and a wide variety of microbial-based products have been applied so far [6,12,[14][15][16][17][18][19][20][21][22][23][24][25][26][27][28]38]. However, the efficacy of soil microbial inoculants under field conditions still remains unpredictable and unreliable, as many factors affect the effectiveness of these products, making them inefficient in cases such as nutrient-poor or unbalanced soils, salinity, increasing temperatures, water stress, diseases, and pests, among others [6,7].…”

“…The low number of publications during the first nine years may mark a turning point of the scientific interest on the broad field of microbial inoculants, while the years 2000-2008 can be considered as the beginning "blooming era" of microbial inoculants in agriculture. Nowadays, the application of microbial inoculants is quickly spreading in a context where humanity is facing high food demand, loss of cultivable land, and climate change with severe environmental impacts [3,29,36,38]. The urgent need for research investment in the microbial-based products for agriculture is mirrored by significant and exponentially increasing publication numbers.…”

“…This clearly highlights the European situation, where this kind of product is consistently produced and commercialized. Bashan and co-workers estimated that the market value of plant growth-promoting rhizobacteria/bacteria (PGPR/PGPB), biological control agents, and biostimulants was valued at USD 6.00 Billion in 2016, and that this will grow following an annual rate of 13.8% up to more than 14.5 Billion by 2023, whereas it is predicted that demand for chemical-based products such as pesticides is expected to decline due to emerging regulatory issues and consumer demand for food with low chemical residues [38]. For example, the EU has set a goal to replace 50% of chemical pesticide usage with biological solutions by 2030 [66].…”

“…In this sense, it was recently reported that the beginning of the PGPR research field has witnessed the use of specific species/strains, later paving the way to the mixture of different bacterial species and raising new and more technical issues [38]. The occurrence of terms like "consortia", "isolate", and "concentration" in the early publications of the green cluster raises the question related to the use of "consortia" over the last decade rather single inoculum, but also describes the "isolation" of microbial inoculant strains raising the question of the "identification" discussed in depth by Bashan and co-workers [38,73]. Moreover, it is evident that bacteria represent the most used microbes for inoculant production.…”

“…In fact, while the vast literature clearly shows their beneficial "traits", several issues, such as the potential environmental impact, the fate and the tracking of the inocula into a new environment [35], and limited knowledge of the interrelationships occurring between microorganisms and plants, are still considerable barriers for a concrete adoption. Moreover, the limited understanding of the ecological traits of most soil microbes is emerging due to the gap between the successful in vitro applications of bioinocula and their success in field conditions [36][37][38]. In this scenario, the present works applied a science mapping approach as a "hand lens" to observe trends, strengths, and weaknesses of their application and to measure the related scientific production.…”