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Microbial fermentations are widely used for the production of chemicals used as pharmaceuticals, food ingredients, materials, solvents, and biofuels. Technoeconomic analysis of a given fermentation process is important to perform before scaling the process to levels that enable commercial production. Titer, rate, and yield (TRY) of the fermentation process are key metrics that are used for technoeconomic analysis. TRY metrics have different impacts on the technoeconomic analysis, and it is important to be aware of these differences. Microbial fermentations offer the opportunity to produce a wide range of chemicals in a sustainable fashion, but it is important to carefully evaluate the production costs. This can be done on the basis of evaluation of the titer, rate, and yield (TRY) of the fermentation process. Here we describe how the three TRY metrics impact the technoeconomics of a microbial fermentation process, and we illustrate the use of these for evaluation of different processes in the production of two commodity chemicals, 1,3-propanediol (PDO) and ethanol, as well as for the fine chemical penicillin. On the basis of our discussions, we provide some recommendations on how the TRY metrics should be reported when new processes are described. [ABSTRACT FROM AUTHOR]

Background/Objectives: Vitamin B12 is very important for human health, as it is a cofactor for enzymatic activities and plays various roles in human physiology. It is highly valued in the pharmaceutical, food, and additive production industries. Some of the bacteria currently used for the vitamin production are difficult to modify with gene-editing tools and may have slow growth. We propose the use of the bacteria Pseudomonas putida KT2440 for the production of vitamin B12 because it has a robust chassis for genetic modifications. The present wok evaluates P. putida KT2440 as a host for vitamin B12 production and explore potential gene-editing optimization strategies. Methods: We curated and modified a genome-scale metabolic model of Pseudomonas putida KT2440 and evaluated different strategies to optimize vitamin B12 production using the knockin and OptGene algorithms from the COBRA Toolbox. Furthermore, we examined the presence of riboswitches as cis-regulatory elements and calculated theoretical biomass growth yields and vitamin B12 production using a flux balance analysis (FBA). Results: According to the flux balance analysis of P. putida KT2440 under culture conditions, the biomass production values could reach 1.802 gDW−1·h1·L−1, and vitamin B12 production could reach 0.359 µmol·gDW−1·h−1·L−1. The theoretical vitamin B12 synthesis rate calculated using P. putida KT2040 with two additional reactions was 14 times higher than that calculated using the control, Pseudomonas denitrificans, which has been used for the industrial production of this vitamin. Conclusions: We propose that, with the addition of aminopropanol linker genes and the modification of riboswitches, P. putida KT2440 may become a suitable host for the industrial production of vitamin B12. [ABSTRACT FROM AUTHOR]

The emergence of new techniques in both microbial biotechnology and artificial intelligence (AI) is opening up a completely new field for monitoring and sometimes even controlling the evolution of pathogens. However, the now famous generative AI extracts and reorganizes prior knowledge from large datasets, making it poorly suited to making predictions in an unreliable future. In contrast, an unfamiliar perspective can help us identify key issues related to the emergence of new technologies, such as those arising from synthetic biology, whilst revisiting old views of AI or including generative AI as a generator of abduction as a resource. This could enable us to identify dangerous situations that are bound to emerge in the not‐too‐distant future, and prepare ourselves to anticipate when and where they will occur. Here, we emphasize the fact that amongst the many causes of pathogen outbreaks, often driven by the explosion of the human population, laboratory accidents are a major cause of epidemics. This review, limited to animal pathogens, concludes with a discussion of potential epidemic origins based on unusual organisms or associations of organisms that have rarely been highlighted or studied. [ABSTRACT FROM AUTHOR]

Microorganisms, including bacteria, archaea, viruses, fungi, and protists, are essential to life on Earth and the functioning of the biosphere. Here, we discuss the key roles of microorganisms in achieving the United Nations Sustainable Development Goals (SDGs), highlighting recent and emerging advances in microbial research and technology that can facilitate our transition toward a sustainable future. Given the central role of microorganisms in the biochemical processing of elements, synthesizing new materials, supporting human health, and facilitating life in managed and natural landscapes, microbial research and technologies are directly or indirectly relevant for achieving each of the SDGs. More importantly, the ubiquitous and global role of microbes means that they present new opportunities for synergistically accelerating progress toward multiple sustainability goals. By effectively managing microbial health, we can achieve solutions that address multiple sustainability targets ranging from climate and human health to food and energy production. Emerging international policy frameworks should reflect the vital importance of microorganisms in achieving a sustainable future. Microbes are essential to life on Earth and will be core, with the advent of exciting new technologies, to our ability to achieve the United Nations Sustainable Development Goals for a sustainable future. [ABSTRACT FROM AUTHOR]

Pelgipeptins, tridecaptins, and elgicins are among the antimicrobials produced by Paenibacillus elgii. Growth in complex media is commonly applied to obtain lipopeptides from culture's supernatant, but it requires further purification. This study aimed to improve the yield of pelgipeptins and tridecaptins using chemically defined media. The kinetics of antimicrobial lipopeptide yield in chemically defined media were evaluated in P. elgii AC13. Pelgipeptins were detected in the supernatant and the culture pellet, but tridecaptins were mainly associated with cell debris or endospores. We investigated whether removing Ca2+ would impair P. elgii sporogenesis, consequently improving the yield of tridecaptin. The kinetics of both lipopeptides in the presence and absence of Ca2+ were quantitatively and qualitatively evaluated and further correlated with the cell cycle. The impairment of P. elgii AC13 sporogenesis had no effect on tridecaptin production, which remained undetected in the supernatant of the culture. On the other hand, the yield of pelgipeptin in a Ca2+-free medium increased. We showed for the first time that the removal of Ca2+ interrupted the sporogenesis in P. elgii and improved the yield of pelgipeptins. However, Ca2+ absence had no effect on tridecaptin yield, which is possibly degraded or associated with other cell debris components. [ABSTRACT FROM AUTHOR]

Abstract—The production of microorganisms that produce biologically active compounds for agriculture and the chemical, veterinary, and pharmaceutical industries, as well as for environmental protection, continues to be an important direction of microbial biotechnology. One of the most effective approaches to the production of producers is chemical mutagenesis, which, in combination with the correct breeding strategy, makes it possible to obtain highly productive strains. A significant disadvantage of chemical mutagenesis is the large number of induced mutations in the genomes of mutant strains, which makes it difficult to identify genes and, accordingly, biosynthetic pathways involved in the production of a given compound. The solution to this problem is modern technologies of genome sequencing and analysis, which make it possible to identify new genes and unknown biochemical pathways involved in the formation of biologically active compounds. The aim of the work was to analyze the genome of the mutant strain B-162/2 of the bacterium Pseudomonas chlororaphis subsp. aurantiaca, which is capable of increased production of biologically active compounds of the phenazine series and is resistant to hydrogen peroxide. When analyzing the genome of strain B-162/2 in full size, 6482 coding sequences and 64 coding RNA sequences were identified. Comparison of the genome of the B-162/2 strain with the genome of the wild type B-162 allowed the identification of 39 mutations, five of which are located in intergenic regions, and 34 affected coding sequences. Of the mutations detected, 14 led to a radical amino acid substitution in the proteins and two led to the formation of premature stop codons (methyl group sensor and MFS-type transporter). Several substitutions with high values of the Grantham coefficient were found, which could possibly lead to a change in the activity of the proteins. Three regions with phage genes in the genome of the B-162/2 strain were detected. [ABSTRACT FROM AUTHOR]

The industrial production of polyhydroxyalkanoates (PHAs) faces several limitations that hinder their competitiveness against traditional plastics, mainly due to high production costs and complex recovery processes. Innovations in microbial biotechnology offer promising solutions to overcome these challenges. The modification of the biosynthetic pathways is one of the main tactics; allowing for direct carbon flux toward PHA formation, increasing polymer accumulation and improving polymer properties. Additionally, techniques have been implemented to expand the range of renewable substrates used in PHA production. These feedstocks are inexpensive and plentiful but require costly and energy-intensive pretreatment. By removing the need for pretreatment and enabling the direct use of these raw materials, microbial biotechnology aims to reduce production costs. Furthermore, improving downstream processes to facilitate the separation of biomass from culture broth and the recovery of PHAs is critical. Genetic modifications that alter cell morphology and allow PHA secretion directly into the culture medium simplify the extraction and purification process, significantly reducing operating costs. These advances in microbial biotechnology not only enhance the efficient and sustainable production of PHAs, but also position these biopolymers as a viable and competitive alternative to petroleum-based plastics, contributing to a circular economy and reducing the dependence on fossil resources. [ABSTRACT FROM AUTHOR]

The present work aimed to evaluate green-nano manganese produced at the Microbial Biotechnology Department, National Research Centre, Egypt, and assess its impact on the growth, yield, and fruit properties of grapevines. To this end, two experiments were conducted. The first was microbiological, where several incorporation strategies were utilized to enrich the yeast with manganese, as follows: (1) manganese was added to the liquid medium (non-growth phase), and (2) manganese was added after 24 h of incubation (growth phase). The results showed that the non-growth phase had a reduced possibility of medium contamination. The manganese concentration in the yeast cells was increased due to manganese sulfate in the medium. The manganese incorporation in yeast cells was 99.93% (1.205 × 105) higher than that of the medium at 0.0195 g/L of manganese. Although the concentration of manganese in the medium raised the optical density (OD) of the yeast cell biomass, manganese sulfate had no passive influence on it. The second experiment was horticultural, where Flame Seedless grapevines were sprayed with frozen and active fresh yeast enriched with manganese that resulted from the microbiological experiment. Grapevines were sprayed twice a year at 10 or 20 cm3/L, and the results were compared with those for the mineral and chelate forms. The results demonstrated that yeast extracts in both forms showed positive effects on grapevine. The most effective treatment with regard to growth, yield, and fruit properties was frozen yeast enriched with manganese at 20 cm3/L, which yielded 10.14 and 12.6 kg/vine, compared with the control, which recorded 3.7 and 5.6 kg/vine in the two seasons, respectively. [ABSTRACT FROM AUTHOR]

L-tryptophan is an essential amino acid widely used in the pharmaceutical and feed industries. Enhancing its production in microorganisms necessitates activating and inactivating specific genes to direct more resources toward its synthesis. In this study, we developed a classification model based on Qualitative Perturbation Analysis and Machine Learning (QPAML). The model uses pFBA to obtain optimal reactions for tryptophan production and FSEOF to introduce perturbations on fluxes of the optima reactions while registering all changes over the iML1515a Genome-Scale Metabolic Network model. The altered reaction fluxes and their relationship with tryptophan and biomass production are translated to qualitative variables classified with GBDT. In the end, groups of enzymatic reactions are predicted to be deleted, overexpressed, or attenuated for tryptophan and 30 other metabolites in E. coli with a 92.34% F1-Score. The QPAML model can integrate diverse data types, promising improved predictions and the discovery of complex patterns in microbial metabolic engineering. It has broad potential applications and offers valuable insights for optimizing microbial production in biotechnology. [ABSTRACT FROM AUTHOR]

EFSA was requested by the European Commission (in accordance with Article 29 of Regulation (EC) No 178/2002) to provide a scientific opinion on the application of new developments in biotechnology (new genomic techniques, NGTs) to viable microorganisms and products of category 4 to be released into the environment or placed on the market as or in food and feed, and to non‐viable products of category 3 to be placed on the market as or in food and feed. A horizon scanning exercise identified a variety of products containing microorganisms obtained with NGTs (NGT‐Ms), falling within the remit of EFSA, that are expected to be placed on the (EU) market in the next 10 years. No novel potential hazards/risks from NGT‐Ms were identified as compared to those obtained by established genomic techniques (EGTs), or by conventional mutagenesis. Due to the higher efficiency, specificity and predictability of NGTs, the hazards related to the changes in the genome are likely to be less frequent in NGT‐Ms than those modified by EGTs and conventional mutagenesis. It is concluded that EFSA guidances are 'partially applicable', therefore on a case‐by‐case basis for specific NGT‐Ms, fewer requirements may be needed. Some of the EFSA guidances are 'not sufficient' and updates are recommended. Because possible hazards relate to genotypic and phenotypic changes introduced and not to the method used for the modification, it is recommended that any new guidance should take a consistent risk assessment approach for strains/products derived from or produced with microorganisms obtained with conventional mutagenesis, EGTs or NGTs. [ABSTRACT FROM AUTHOR]

Soybean meal is a co-product of soybean oil extraction, and is the main protein source as its high protein content, well-balanced amino acid profile, and abundant supplies. However, the presence of anti-nutritional factors (ANFs) in the soybean meal affects the growth performance, reduces the apparent digestibility and utilization of nutrients, and induces intestinal disorder. This review aims to discuss the ANFs that limit the application of soybean meal, and compare their elimination methods. Then, the biotechnology strategy based on anti-nutritional factor degradation and beneficial metabolites accumulation are recommended. Moreover, the combination of conventional indicators and untargeted metabolomics technology to establish the quality evaluation system of fermented soybean meal with the perspective of postbiotics have been proposed. This review provides the first quantitative summary of anti-nutritional factors in the soybean meal, and compares the emergent biotechnology strategies for the elimination of ANFs in the soybean meal with existing practical methods, which could promote the efficient use of fermented soybean meal in the animal farming industry. [ABSTRACT FROM AUTHOR]

Introduction: The identification of microbe-drug associations can greatly facilitate drug research and development. Traditional methods for screening microbe-drug associations are time-consuming, manpower-intensive, and costly to conduct, so computational methods are a good alternative. However, most of them ignore the combination of abundant sequence, structural information, and microbe-drug network topology. Methods: In this study, we developed a computational framework based on a modified graph attention variational autoencoder (MGAVAEMDA) to infer potential microbedrug associations by combining biological information with the variational autoencoder. In MGAVAEMDA, we first used multiple databases, which include microbial sequences, drug structures, and microbe-drug association databases, to establish two comprehensive feature matrices of microbes and drugs after multiple similarity computations, fusion, smoothing, and thresholding. Then, we employed a combination of variational autoencoder and graph attention to extract low-dimensional feature representations of microbes and drugs. Finally, the lowdimensional feature representation and graphical adjacency matrix were input into the random forest classifier to obtain the microbe-drug association score to identify the potential microbe-drug association. Moreover, in order to correct the model complexity and redundant calculation to improve efficiency, we introduced a modified graph convolutional neural network embedded into the variational autoencoder for computing low dimensional features. Results: The experiment results demonstrate that the prediction performance of MGAVAEMDA is better than the five state-of-the-art methods. For the major measurements (AUC =0.9357, AUPR =0.9378), the relative improvements of MGAVAEMDA compared to the suboptimal methods are 1.76 and 1.47%, respectively. Discussion: We conducted case studies on two drugs and found that more than 85% of the predicted associations have been reported in PubMed. The comprehensive experimental results validated the reliability of our models in accurately inferring potential microbe-drug associations. [ABSTRACT FROM AUTHOR]

Bdellovibrio bacteriovorus HD100 is an obligate predatory bacterium that preys upon Gram‐negative bacteria. It has been proposed to be applied as a "living antibiotic" in several fields such as agriculture or even medicine, since it is able to prey upon bacterial pathogens. Its interesting lifestyle makes this bacterium very attractive as a microbial chassis for co‐culture systems including two partners. A limitation to this goal is the scarcity of suitable synthetic biology tools for predator domestication. To fill this gap, we have firstly adapted the hierarchical assembly cloning technique Golden Standard (GS) to make it compatible with B. bacteriovorus HD100. The chromosomal integration of the Tn7 transposon's mobile element, in conjunction with the application of the GS technique, has allowed the systematic characterization of a repertoire of constitutive and inducible promoters, facilitating the control of the expression of heterologous genes in this bacterium. PJExD/EliR proved to be an exceptional promoter/regulator system in B. bacteriovorus HD100 when precise regulation is essential, while the synthetic promoter PBG37 showed a constitutive high expression. These genetic tools represent a step forward in the conversion of B. bacteriovorus into an amenable strain for microbial biotechnology approaches. [ABSTRACT FROM AUTHOR]

The shift from fossil fuels to renewable energy sources is crucial in addressing environmental challenges. Vegetable oils have been focused on as the main potential source for biodiesel and biolubricant production. However, due to their fatty acid (FA) composition they are characterized by low stability to oxidation and variable viscosity. Single-cell oils (SCOs) from oleaginous microorganisms are a possible alternative to vegetable oils: their composition is more suitable, and it can further be improved by controlling the fermentation's physiological conditions. In the present study, the production of SCOs with targeted technological properties from Lipomyces starkeyi in fermentation under controlled temperatures was assessed. A dairy effluent (scotta) was used as the fermentation substrate to improve the economic sustainability of the process. Batch aerobic fermentations were carried out in a fermenter at two different temperatures (25 °C and 30 °C). The fermentation yields and SCO FA profiles were analyzed. The highest yields of biomass (9.76 g L−1) and microbial oil (1.83 g L−1) were obtained from fermentations carried out at 30 °C. Furthermore, a significantly lower content (46% vs. 55%) of unsaturated FAs and higher content (11% vs. 1.5%) of shorter-chain saturated FAs, with myristic acid almost matching stearic acid, were detected at 30 °C in comparison to 25 °C. Very low peroxide values were also found (0.14 meq O2 kg−1 at 30 °C and 0 meq O2 kg−1 at 25 °C). These results indicate that these SCOs were highly oxidation-resistant, and that a higher fermentation temperature improves their oxidative stability and tribophysical features. The biodiesels' technological properties, calculated from the FA composition, were within the limits of both U.S. standards and E.U. regulations. Then, SCOs produced from L. starkeyi by fermentation of dairy effluents carried out under controlled temperature can be considered a suitable alternative to vegetable oils to produce biodiesel and biolubricants. [ABSTRACT FROM AUTHOR]

Synthetic polymers, commonly known as plastics, are currently present in all aspects of our lives. Although they are useful, they present the problem of what to do with them after their lifespan. There are currently mechanical and chemical methods to treat plastics, but these are methods that, among other disadvantages, can be expensive in terms of energy or produce polluting gases. A more environmentally friendly alternative is recycling, although this practice is not widespread. Based on the practice of the so-called circular economy, many studies are focused on the biodegradation of these polymers by enzymes. Using enzymes is a harmless method that can also generate substances with high added value. Novel and enhanced plastic-degrading enzymes have been obtained by modifying the amino acid sequence of existing ones, especially on their active site, using a wide variety of genetic approaches. Currently, many studies focus on the common aim of achieving strains with greater hydrolytic activity toward a different range of plastic polymers. Although in most cases the depolymerization rate is improved, more research is required to develop effective biodegradation strategies for plastic recycling or upcycling. This review focuses on a compilation and discussion of the most important research outcomes carried out on microbial biotechnology to degrade and recycle plastics. [ABSTRACT FROM AUTHOR]

Entomopathogenic fungi, often acknowledged primarily for their insecticidal properties, fulfill diverse roles within ecosystems. These roles encompass endophytism, antagonism against plant diseases, promotion of the growth of plants, and inhabitation of the rhizosphere, occurring both naturally and upon artificial inoculation, as substantiated by a growing body of contemporary research. Numerous studies have highlighted the beneficial aspects of endophytic colonization. This review aims to systematically organize information concerning the direct (nutrient acquisition and production of phytohormones) and indirect (resistance induction, antibiotic and secondary metabolite production, siderophore production, and mitigation of abiotic and biotic stresses) implications of endophytic colonization. Furthermore, a thorough discussion of these mechanisms is provided. Several challenges, including isolation complexities, classification of novel strains, and the impact of terrestrial location, vegetation type, and anthropogenic reluctance to use fungal entomopathogens, have been recognized as hurdles. However, recent advancements in biotechnology within microbial research hold promising solutions to many of these challenges. Ultimately, the current constraints delineate potential future avenues for leveraging endophytic fungal entomopathogens as dual microbial control agents. [ABSTRACT FROM AUTHOR]

The growing preference for incorporating microbial aspartic proteases in industries is due to their high catalytic function and high degree of substrate selectivity. These properties, however, are attributable to molecular alterations in their structure and a variety of other characteristics. Molecular tools, functional genomics, and genome editing technologies coupled with other biotechnological approaches have aided in improving the potential of industrially important microbial proteases by addressing some of their major limitations, such as: low catalytic efficiency, low conversion rates, low thermostability, and less enzyme yield. However, the native folding within their full domain is dependent on a surrounding structure which challenges their functionality in substrate conversion, mainly due to their mutual interactions in the context of complex systems. Hence, manipulating their structure and controlling their expression systems could potentially produce enzymes with high selectivity and catalytic functions. The proteins produced by microbial aspartic proteases are industrially capable and far-reaching in regulating certain harmful distinctive industrial processes and the benefits of being eco-friendly. This review provides: an update on current trends and gaps in microbial protease biotechnology, exploring the relevant recombinant strategies and molecular technologies widely used in expression platforms for engineering microbial aspartic proteases, as well as their potential industrial and biotechnological applications. [ABSTRACT FROM AUTHOR]

Porphyrins, phycobilins, and their proteins have abundant π-electrons and strongly absorb visible light, some of which bind a metal ion in the center. Because of the structural and optical properties, they not only play critical roles as an essential component in natural systems but also have attracted much attention as a high value specialty chemical in various fields, including renewable energy, cosmetics, medicines, and foods. However, their commercial application seems to be still limited because the market price of porphyrins and phycobilins is generally expensive to apply them easily. Furthermore, their petroleum-based chemical synthesis is energy-intensive and emits a pollutant. Recently, to replace petroleum-based production, many studies on the bioproduction of metalloporphyrins, including Zn-porphyrin, Co-porphyrin, and heme, porphyrin derivatives including chlorophyll, biliverdin, and phycobilins, and their proteins including hemoproteins, phycobiliproteins, and phytochromes from renewable carbon sources using microbial cell factories have been reported. This review outlines recent advances in the bioproduction of porphyrins, phycobilins, and their proteins using microbial cell factories developed by various microbial biotechnology techniques, provides well-organized information on metabolic regulations of the porphyrin metabolism, and then critically discusses challenges and future perspectives. Through these, it is expected to be able to achieve possible solutions and insights and to develop an outstanding platform to be applied to the industry in future research. [ABSTRACT FROM AUTHOR]

This review aims to analyze the technological and scientific applications regarding cocoa fermentation through a prospective study of patent documents and research articles. The Espacenet database was used as a patent research tool by searching both the IPC code "A23G1" and the terms "cocoa" and "ferment*". A total of 130 documents were found—49 were related to the subject. The Scopus database was also searched for scientific articles using the terms "cocoa" and "fermentation". A total of 812 articles were found—517 were related to the subject. Cocoa fermentation has not yet reached technological maturity, despite the growth in patent documents and scientific research observed in the last two decades. The creation of the Cacao of Excellence Program (2009), among others, has incentivized sustainability and quality in cocoa-producing countries. Brazil, Colombia, and Indonesia are leading with scientific publications in the last 5 years, despite the lack of patents filed. The United Kingdom, France, China, Canada, and Germany, despite not being cocoa-producing countries, are the main holders of the technology. Patent documents analyzed relate to food science, biotechnology, engineering, and chemistry. Microbial biotechnology has gained attention as a key factor to produce a higher-quality cocoa bean. Saccharomyces is the most frequent genus of yeast used as a starter culture in patent documents. Some patent documents propose the addition of fruits during cocoa fermentation, but a few scientific studies have been found on the matter. Overall, technological applications and scientific studies have focused on improving cocoa quality. The cocoa market is expected to increase significantly in the next few years, representing an opportunity to develop high-quality cocoa using novel fermentation techniques. [ABSTRACT FROM AUTHOR]

Excessive fluoride consumption (> 2.0 mg/L) results in fluorosis, teeth staining, or bone weakening. It is critical to concentrate on the defluoridation of water. Adsorption has been a conventional method of fluoride removal in aqueous solution. Biosorbents are cost-effective, easily obtainable, and ecologically sustainable sources of adsorbents. In this study, aqueous fluoride solution is treated with dead bacterial biomass. Effects of process conditions like initial fluoride concentration, biomass dosage, pH, temperature, and contact time have been studied. Central Composite Design (CCD) with 30 experiments is performed. The centre point experimental conditions have been repeated 6 times. The optimum fluoride biosorption of 76.89% is observed after 8 h of biosorption with 3.25 mg L-1 initial fluoride concentration, 775 mg L-1 of biomass dosage, at temperature 55 °C and pH 4.5. R² value of the experimental design is found to be 0.92. Biosorption kinetic studies revealed that fluoride biosorption followed a pseudo-second-order kinetics and adsorption isotherm is best described by Freundlich isotherm. The biosorption efficiency of immobilised biosorbent is also studied using column approach. Biosorbent is characterised using SEM, FTIR and EDX techniques. The desorption and recyclability studies suggest that dead bacterial biomass could serve as a potential biosorbent for fluoride biosorption. [ABSTRACT FROM AUTHOR]

Plastics pollution has become one of the greatest concerns of the 21st century. To date, around 10 billion tons of plastics have been produced almost exclusively from non‐renewable sources, and of these, <10% have been recycled. The majority of discarded plastic waste (>70%) is accumulating in landfills or the environment, causing severe impacts to natural ecosystems and human health. Considering how plastics are present in every aspect of our daily lives, it is evident that a transition towards a Circular Economy of plastics is essential to achieve several of the Sustainable Development Goals. In this editorial, we highlight how microbial biotechnology can contribute to this shift, with a special focus on the biological recycling of conventional plastics and the upcycling of plastic‐waste feedstocks into new value‐added products. Although important hurdles will need to be overcome in this endeavour, recent success stories highlight how interdisciplinary approaches can bring us closer to a bio‐based economy for the sustainable management of plastics. [ABSTRACT FROM AUTHOR]

Electronic waste is an alarming problem faced globally in today's constantly changing world of technological innovations. The major challenge is to create various innovative and cost-effective ways for decontaminating polluted environments so that they are safe for human habitation, consumption and functioning of various ecosystems that support life. To date, for the management of e-waste no sound eco-friendly technique is available. Hence, biological approach using microorganisms is currently being applied for recovering leached metals from contaminated soil, groundwater, surface water polluted by e-waste, removing toxicity and decontamination of these abiotic components polluted due to e-waste. There are different technologies used for management of e-waste using microorganisms which include microremediation, phytoremediation and vermiremediation. Microremediation involves the use of various microorganisms, phytoremediation the use of plants and symbiotic microorganisms, whereas vermiremediation involves the use of earthworms and necessary associated microbes for e-waste management. These technologies are becoming attractive alternatives as compared to the primitive disposal technologies because they are cost effective, work at ambient temperatures, do not have any major environmental impacts, generate minimum secondary waste and have an inherently aesthetic nature. This paper summarizes the status of ewaste and its harmful effects on life as well as environment and use of innovative microbial biotechnological approaches for handling of e-waste and metal recovery thereof. [ABSTRACT FROM AUTHOR]

Background/Objectives: Vitamin B12 is very important for human health, as it is a cofactor for enzymatic activities and plays various roles in human physiology. It is highly valued in the pharmaceutical, food, and additive production industries. Some of the bacteria currently used for the vitamin production are difficult to modify with gene-editing tools and may have slow growth. We propose the use of the bacteria Pseudomonas putida KT2440 for the production of vitamin B12 because it has a robust chassis for genetic modifications. The present wok evaluates P. putida KT2440 as a host for vitamin B12 production and explore potential gene-editing optimization strategies. Methods: We curated and modified a genome-scale metabolic model of Pseudomonas putida KT2440 and evaluated different strategies to optimize vitamin B12 production using the knockin and OptGene algorithms from the COBRA Toolbox. Furthermore, we examined the presence of riboswitches as cis-regulatory elements and calculated theoretical biomass growth yields and vitamin B12 production using a flux balance analysis (FBA). Results: According to the flux balance analysis of P. putida KT2440 under culture conditions, the biomass production values could reach 1.802 gDW−1·h1·L−1, and vitamin B12 production could reach 0.359 µmol·gDW−1·h−1·L−1. The theoretical vitamin B12 synthesis rate calculated using P. putida KT2040 with two additional reactions was 14 times higher than that calculated using the control, Pseudomonas denitrificans, which has been used for the industrial production of this vitamin. Conclusions: We propose that, with the addition of aminopropanol linker genes and the modification of riboswitches, P. putida KT2440 may become a suitable host for the industrial production of vitamin B12.

Microbes are powerful upgraders, able to convert simple substrates to nutritional metabolites at rates and yields surpassing those of higher organisms by a factor of 2 to 10. A summary table highlights the superior efficiencies of a whole array of microbes compared to conventionally farmed animals and insects, converting nitrogen and organics to food and feed. Aiming at the most resource‐efficient class of microbial proteins, deploying the power of open microbial communities, coined here as 'symbiotic microbiomes' is promising. For instance, a production train of interest is to develop rumen‐inspired technologies to upgrade fibre‐rich substrates, increasingly available as residues from emerging bioeconomy initiatives. Such advancements offer promising perspectives, as currently only 5%–25% of the available cellulose is recovered by ruminant livestock systems. While safely producing food and feed with open cultures has a long‐standing tradition, novel symbiotic fermentation routes are currently facing much higher market entrance barriers compared to axenic fermentation. Our global society is at a pivotal juncture, requiring a shift towards food production systems that not only embrace the environmental and economic sustainability but also uphold ethical standards. In this context, we propose to re‐examine the place of spontaneous or natural microbial consortia for safe future food and feed biotech developments, and advocate for intelligent regulatory practices. We stress that reconsidering symbiotic microbiomes is key to achieve sustainable development goals and defend the need for microbial biotechnology literacy education. [ABSTRACT FROM AUTHOR]

In microbial electrochemical cells (MECs), electroactive microbial biofilms can transmit electrons from organic molecules to anodes. To further understand the production of anodic biofilms, it is essential to investigate the composition and distribution of extracellular polymeric substance (EPS) in the MECs. In this study, the structure of EPS was examined in microbial electrolysis cells from mixed cultures forming biofilm using carbon fiber fabric anode. EPS was extracted from the anode biofilm of microbial electrolysis cells inoculated with mixed microbial culture. The anode biofilm yielded 0.4 mg of EPS, of which 51.2% was humic substance, 16.2% was protein, 12.6% was carbohydrates, and 20% consisted of undetermined substances. Using epifluorescence microscopy, the composition of bacterial cells and their location inside EPS were studied, and the distribution of microbial communities was compared based on current density results in the presence of various carbohydrates. On the electrode surface, bacteria and EPS gathered or overlapped in various locations can affect microbial electrochemical performance. Our findings showed that EPS formation in electroactive biofilms would be important for enhanced efficiency of electricity- or hydrogen-producing microbial electrolysis cells. [ABSTRACT FROM AUTHOR]

This comprehensive article critically analyzes the advanced biotechnological strategies to mitigate plant drought stress. It encompasses an in-depth exploration of the latest developments in plant genomics, proteomics, and metabolomics, shedding light on the complex molecular mechanisms that plants employ to combat drought stress. The study also emphasizes the significant advancements in genetic engineering techniques, particularly CRISPR-Cas9 genome editing, which have revolutionized the creation of drought-resistant crop varieties. Furthermore, the article explores microbial biotechnology's pivotal role, such as plant growth-promoting rhizobacteria (PGPR) and mycorrhizae, in enhancing plant resilience against drought conditions. The integration of these cutting-edge biotechnological interventions with traditional breeding methods is presented as a holistic approach for fortifying crops against drought stress. This integration addresses immediate agricultural needs and contributes significantly to sustainable agriculture, ensuring food security in the face of escalating climate change challenges. [ABSTRACT FROM AUTHOR]

The phyllosphere, or plant leaf surface, represents a microbial ecosystem of considerable size, holding extraordinary biodiversity and enormous potential for the discovery of new products, tools, and applications in biotechnology, agriculture, medicine, and elsewhere. This mini-review highlights the applied microbiology of the phyllosphere as an original field of study concerning itself with the genes, gene products, natural compounds, and traits that underlie phyllosphere-specific adaptations and services that have commercial and economic value for current or future innovation. Examples include plant-growth-promoting and disease-suppressive phyllobacteria, probiotics and fermented foods that support human health, as well as microbials that remedy foliar contamination with airborne pollutants, residual pesticides, or plastics. Phyllosphere microbes promote plant biomass conversion into compost, renewable energy, animal feed, or fiber. They produce foodstuffs such as thickening agents and sugar substitutes, industrial-grade biosurfactants, novel antibiotics and cancer drugs, as well as enzymes used as food additives or freezing agents. Furthermore, new developments in DNA sequence-based profiling of leaf-associated microbial communities allow for surveillance approaches in the context of food safety and security, for example, to detect enteric human pathogens on leafy greens, predict plant disease outbreaks, and intercept plant pathogens and pests on internationally traded goods. Key points: • Applied phyllosphere microbiology concerns leaf-specific adaptations for economic value • Phyllobioprospecting searches the phyllosphere microbiome for product development • Phyllobiomonitoring tracks phyllosphere microbial profiles for early risk detection [ABSTRACT FROM AUTHOR]

The plants of the genus Salacia L. are the storehouse of several bioactive compounds, and are involved in treating human diseases and disorders. Hitherto, a number of reports have been published on in vitro biotechnology as well as microbial involvement in the improvement of Salacia spp. The present review provides comprehensive insights into biotechnological interventions such as tissue culture for plant propagation, in vitro cultures, and endophytic microbes for up-scaling the secondary metabolites and biological potential of Salacia spp. Other biotechnological interventions such as molecular markers and bio-nanomaterials for up-grading the prospective of Salacia spp. are also considered. The in vitro biotechnology of Salacia spp. is largely focused on plant regeneration, callus culture, cell suspension culture, somatic embryogenesis, and subsequent ex vitro establishment of the in vitro–raised plantlets. The compiled information on tissue cultural strategies, involvement of endophytes, molecular markers, and nanomaterials will assist the advanced research related to in vitro manipulation, domestication, and commercial cultivation of elite clones of Salacia spp. Moreover, the genetic diversity and other molecular-marker based assessments will aid in designing conservation policies as well as support upgrading and breeding initiatives for Salacia spp. Key points: • Salacia spp. plays a multifaceted role in human health and disease management. • Critical and updated assessment of tissue culture, endophytic microbes, metabolites, molecular markers, and bio-nanomaterials of Salacia spp. • Key shortcomings and future research directions for Salacia biotechnology. [ABSTRACT FROM AUTHOR]

Vitamin K2 (menaquinone, VK2, MK) is an essential lipid-soluble vitamin that plays critical roles in inhibiting cell ferroptosis, improving blood clotting, and preventing osteoporosis. The increased global demand for VK2 has inspired interest in novel production strategies. In this review, various novel metabolic regulation strategies, including static and dynamic metabolic regulation, are summarized and discussed. Furthermore, the advantages and disadvantages of both strategies are analyzed in-depth to highlight the bottlenecks facing microbial VK2 production on an industrial scale. Finally, advanced metabolic engineering biotechnology for future microbial VK2 production will also be discussed. In summary, this review provides in-depth information and offers an outlook on metabolic engineering strategies for VK2 production. [ABSTRACT FROM AUTHOR]

Anthropogenic pollution, including residues from the green revolution initially aimed at addressing food security and healthcare, has paradoxically exacerbated environmental challenges. The transition towards comprehensive green biotechnology and bioremediation, achieved with lower financial investment, hinges on microbial biotechnology, with the Rhodococcus genus emerging as a promising contender. The significance of fully annotating genome sequences lies in comprehending strain constituents, devising experimental protocols, and strategically deploying these strains to address pertinent issues using pivotal genes. This study revolves around Rhodococcus erythropolis MGMM8, an associate of winter wheat plants in the rhizosphere. Through the annotation of its chromosomal genome and subsequent comparison with other strains, its potential applications were explored. Using the antiSMASH server, 19 gene clusters were predicted, encompassing genes responsible for antibiotics and siderophores. Antibiotic resistance evaluation via the Comprehensive Antibiotic Resistance Database (CARD) identified five genes (vanW, vanY, RbpA, iri, and folC) that were parallel to strain CCM2595. Leveraging the NCBI Prokaryotic Genome Annotation Pipeline (PGAP) for biodegradation, heavy metal resistance, and remediation genes, the presence of chlorimuron-ethyl, formaldehyde, benzene-desulfurization degradation genes, and heavy metal-related genes (ACR3, arsC, corA, DsbA, modA, and recG) in MGMM8 was confirmed. Furthermore, quorum-quenching signal genes, critical for curbing biofilm formation and virulence elicited by quorum-sensing in pathogens, were also discerned within MGMM8's genome. In light of these predictions, the novel isolate MGMM8 warrants phenotypic assessment to gauge its potential in biocontrol and bioremediation. This evaluation extends to isolating active compounds for potential antimicrobial activities against pathogenic microorganisms. The comprehensive genome annotation process has facilitated the genetic characterization of MGMM8 and has solidified its potential as a biotechnological strain to address global anthropogenic predicaments. [ABSTRACT FROM AUTHOR]

The industrial production of polyhydroxyalkanoates (PHAs) faces several limitations that hinder their competitiveness against traditional plastics, mainly due to high production costs and complex recovery processes. Innovations in microbial biotechnology offer promising solutions to overcome these challenges. The modification of the biosynthetic pathways is one of the main tactics; allowing for direct carbon flux toward PHA formation, increasing polymer accumulation and improving polymer properties. Additionally, techniques have been implemented to expand the range of renewable substrates used in PHA production. These feedstocks are inexpensive and plentiful but require costly and energy-intensive pretreatment. By removing the need for pretreatment and enabling the direct use of these raw materials, microbial biotechnology aims to reduce production costs. Furthermore, improving downstream processes to facilitate the separation of biomass from culture broth and the recovery of PHAs is critical. Genetic modifications that alter cell morphology and allow PHA secretion directly into the culture medium simplify the extraction and purification process, significantly reducing operating costs. These advances in microbial biotechnology not only enhance the efficient and sustainable production of PHAs, but also position these biopolymers as a viable and competitive alternative to petroleum-based plastics, contributing to a circular economy and reducing the dependence on fossil resources.

The Lachnospiraceae is a family of anaerobic bacteria in the class Clostridia with potential to advance the bio-economy and intestinal therapeutics. Some species of Lachnospiraceae metabolize abundant, low-cost feedstocks such as lignocellulose and carbon dioxide into value-added chemicals. Others are among the dominant species of the human colon and animal rumen, where they ferment dietary fiber to promote healthy gut and immune function. Here, we summarize recent studies of the physiology, cultivation, and genetics of Lachnospiraceae, highlighting their wide substrate utilization and metabolic products with industrial applications. We examine studies of these bacteria as Live Biotherapeutic Products (LBPs), focusing on in vivo disease models and clinical studies using them to treat infection, inflammation, metabolic syndrome, and cancer. We discuss key research areas including elucidation of intra-specific diversity and genetic modification of candidate strains that will facilitate the exploitation of Lachnospiraceae in industry and medicine.

Summary: Saccharomyces cerevisiae adjusts its metabolism based on nutrient availability, typically transitioning from glucose fermentation to ethanol respiration as glucose becomes limiting. However, our understanding of the regulation of metabolism is largely based on population averages, whereas nutrient transitions may cause heterogeneous responses. Here we introduce iCRAFT, a method that couples the ATP Förster resonance energy transfer (FRET)-based biosensor yAT1.03 with Antimycin A to differentiate fermentative and respiratory metabolisms in individual yeast cells. Upon Antimycin A addition, respiratory cells experienced a sharp decrease of the normalized FRET ratio, while respiro-fermentative cells showed no response. Next, we tracked changes in metabolism during the diauxic shift of a glucose pre-grown culture. Following glucose exhaustion, the entire cell population experienced a progressive rise in cytosolic ATP produced via respiration, suggesting a gradual increase in respiratory capacity. Overall, iCRAFT is a robust tool to distinguish fermentation from respiration, offering a new single-cell opportunity to study yeast metabolism.

Continuous improvement in the living standards of developing countries, calls for an urgent need of high quality meat and dairy products. The farm animals have a micro-ecosystem in gastro-intestinal tract, comprising of a wide variety of flora and fauna which converts roughages and agricultural byproducts as well as nutrient rich concentrate sources into the useful products such as volatile fatty acids and microbial crude proteins. The microbial diversity changes according to composition of the feed, host species/breed and host's individual genetic makeup. From culture methods to next-generation sequencing technologies, the knowledge has emerged a lot to know-how of microbial world viz. their identification, enzymatic activities and metabolites which are the keys of ruminant's successful existence. The structural composition of ruminal community revealed through metagenomics can be elaborated by metatranscriptomics and metabolomics through deciphering their functional role in metabolism and their responses to the external and internal stimuli. These highly sophisticated analytical tools have made possible to correlate the differences in the feed efficiency, nutrients utilization and methane emissions to their rumen microbiome. The comprehensively understood rumen microbiome will enhance the knowledge in the fields of animal nutrition, biotechnology and climatology through deciphering the significance of each and every domain of residing microbial entity. The present review undertakes the recent investigations regarding rumen multi-omics viz. taxonomic and functional potential of microbial populations, host–diet–microbiome interactions and correlation with metabolic dynamics. [ABSTRACT FROM AUTHOR]

Strains of micromycetes and bacteria with lipolytic activity were isolated from oil palm biomass waste. Phylogenetic analysis showed that the obtained micromycetes are closely related to Penicillium chrysogenum, P. goetzii, P. citreosulfuratum, P. citrinum, Paecilomyces lilacinus, and Aspergillus hortae. Opportunistic microorganisms prevailed among the bacterial isolates. The non-opportunistic isolate Pseudomonas sp. Z-M-7T2 exhibited lipolytic activity but did not show active utilization of palm oil. The study showed that micromycete strains related to P.chrysogenum and P.goetzii are most promising for decomposition of oil palm biomass waste. [ABSTRACT FROM AUTHOR]

Microbial biotechnology plays a crucial role in improving industrial processes, particularly in the production of compounds with diverse applications. In this study, we used bioinformatic approaches to analyze the genomic architecture of Streptomyces albidoflavus MGMM6 and identify genes involved in various metabolic pathways that have significant biotechnological potential. Genome mining revealed that MGMM6 consists of a linear chromosome of 6,932,303 bp, with a high G+C content of 73.5%, lacking any plasmid contigs. Among the annotated genes, several are predicted to encode enzymes such as dye peroxidase, aromatic ring-opening dioxygenase, multicopper oxidase, cytochrome P450 monooxygenase, and aromatic ring hydroxylating dioxygenases which are responsible for the biodegradation of numerous endogenous and xenobiotic pollutants. In addition, we identified genes associated with heavy metal resistance, such as arsenic, cadmium, mercury, chromium, tellurium, antimony, and bismuth, suggesting the potential of MGMM6 for environmental remediation purposes. The analysis of secondary metabolites revealed the presence of multiple biosynthesis gene clusters responsible for producing compounds with potent antimicrobial and metal-chelating activities. Furthermore, laboratory tests conducted under controlled conditions demonstrated the effectiveness of MGMM6 in inhibiting phytopathogenic microbes, decolorizing and degrading aromatic triphenylmethane dyes, particularly Blue Brilliant G250, from wastewater by up to 98 ± 0.15%. Overall, the results of our study highlight the promising biotechnological potential of S. albidoflavus MGMM6. [ABSTRACT FROM AUTHOR]

Therefore, new strategies should be developed for food production that optimizes land productivity, without harming the environment, and new sources of nutrients should be made available. Food fermentation is the most economical method to produce and preserve food, and it is the most ancient method that all cultures have used (Rizo et al., [17]). However, symbiotic nitrogen fixation by the I Rhizobium i -legume interaction has been widely studied in the light of sustainable production of food (Lindström & Mousavi, [14]). The 17 sustainable developmental goals (SDGs) established by the United Nations (UN) General assembly in 2015 are the following: No poverty. [Extracted from the article]

The optimizing stocking density for biofloc technology is essential for improving fish growth and profitability of aquaculture. The treatments consisted of different stocking density of 125, 250, 375, and 500 common carp (Cyprinus carpio) fish/m³. Fish with an initial average weight of 17.10±0.3 g were fed three times per day in triplicates for 40 days with a commercial diet (25% crude protein), and the ratio of carbon to nitrogen 20 in each treatment. The water nitrogen substances enhanced by increased stocking density (P<0.05). The final growth (-19.75%), whole-body protein (-2.84%), lipid content (-7.27%) significantly decreased, and food conversion ratio (+67.29%) increased in the treatment of 500 fish/m³ compared to the treatment of 250 fish/m³ (P<0.05). Serum glucose (-11.09%), triglycerides (-11.24%), high-density lipoprotein (-26.16%), and low-density lipoprotein (-31.98%) levels significantly reduced, but serum cortisol concentrations (+13.08%) and, liver enzymes increased in the treatment of 500 fish/m³ compared to the treatment of 250 fish/m³ (P<0.05). Total protein (-9.01%), globulin (-12.80%), ACH50 (-4.97%), and lysozyme activity (-9.21%) significantly reduced in the treatment of 500 fish/m³ compared to the treatment of 250 fish/m³ (P<0.05). The best performance of fish was observed at stocking density up to 250 fish/m³ in the biofloc system. [ABSTRACT FROM AUTHOR]

Microbially assisted bio-oxidation of sulfide concentrates in stirred-tank reactors (stirred-tank reactor bio-oxidation (STRB)) and acid pressure oxidation (POX) are widely used to pretreat refractory sulfide concentrates and increase gold extraction via cyanidation. Continuous STRB requires a comparatively long residence time; however, in some cases, it cannot effectively oxidize some sulfide minerals. POX enables oxidation in a short residence time. At the same time, if a processed concentrate contains a large amount of sulfur, it decreases the ratio of the solid mineral phase to liquid (pulp density) during POX and limits its economic attractiveness. In the present work, experiments were performed to investigate the problems associated with both processing methods for refractory sulfide concentrates. The experiments combined both treatments (STRB and POX) based on the example of a pyrite–arsenopyrite gold-bearing concentrate. The gold recovery from the untreated concentrate via cyanidation reached 58%. Continuous STRB for 2, 4, and 6 days oxidized 43, 74, and 79% of the sulfide sulfur (Ss), respectively. The gold recovery rates from the bio-oxidation residues were 68, 82, and 88%, respectively. The pressure oxidation of both the concentrate and STRB residues increased Ss oxidation by 97–99% and gold recovery by 96–97%. For 2 days, STRB decreased the Ss content and increased the possible liquid-to-solid ratio for POX. The combined processes result in a new promising direction because the POX stage allows high gold recovery, whereas combining STRB and POX provides products for further POX in terms of Ss content and increases POX productivity. [ABSTRACT FROM AUTHOR]

Hydroxytyrosol (HT) is a phenolic substance primarily present in olive leaves and olive oil. Numerous studies have shown its advantages for human health, making HT a potentially active natural component with significant added value. Determining strategies for its low-cost manufacturing by metabolic engineering in microbial factories is hence still of interest. The objective of our study was to assess and improve HT production in a one-liter bioreactor utilizing genetically modified Escherichia coli strains that had previously undergone fed-batch testing. Firstly, we compared the induction temperatures in small-scale whole-cell biocatalysis studies and then examined the optimal temperature in a large volume bioreactor. By lowering the induction temperature, we were able to double the yield of HT produced thereby, reaching 82% when utilizing tyrosine or L-DOPA as substrates. Hence, without the need to further modify our original strains, we were able to increase the HT yield. [ABSTRACT FROM AUTHOR]

Hydrogen offers a source of energy that does not produce any greenhouse gas (GHG) when combusted. However, some hydrogen manufacturing methods consume large amounts of energy and produce carbon dioxide as a byproduct. The production of hydrogen by bacteria is an attractive alternative because it is not energy intensive and, under the right conditions, does not release GHG. In this review, we introduce the five known ways by which bacteria can evolve hydrogen. We then describe methods to encapsulate living bacteria in synthetic layers, called biocoatings, for applications in bioreactors. We review the few examples in which biocoatings have been used to produce hydrogen via the photofermentation method. Although not used in biocoatings so far, the dark fermentation method of hydrogen production avoids the need for illumination while offering a high yield with low oxygen evolution. We identify the potential for using genetically-modified bacteria in future research on biocoatings. [ABSTRACT FROM AUTHOR]

The importance of Saccharomyces cerevisiae yeast cells is known worldwide, as they are the most used microorganisms in biotechnology for bioethanol and biofuel production. Also, they are analyzed and studied for their similar internal biochemical processes to human cells, for a better understanding of cell aging and response to cell stressors. The special ability of S. cerevisiae cells to develop in both aerobic and anaerobic conditions makes this microorganism a viable model to study the transformations and the way in which cellular metabolism is directed to face the stress conditions due to environmental changes. Thus, this review will emphasize the effects of oxidative, ethanol, and osmotic stress and also the physiological and genetic response of stress mitigation in yeast cells. [ABSTRACT FROM AUTHOR]

The application of plant growth-promoting rhizobacteria (PGPRs) can be an excellent and eco-friendly alternative to the use of chemical fertilizers. While PGPRs are often used in traditional agriculture to facilitate yield increases, their use in soilless agriculture has been limited. Soilless agriculture is growing in popularity among commercial farmers because it eliminates soil-borne problems, and the essential strategy is to keep the system as clean as possible. However, a new trend is the inclusion of PGPRs to enhance plant development. Despite the plethora of research that has been performed to date, there remains a huge knowledge gap that needs to be addressed to facilitate the commercialization of PGPRs for sustainable soilless agriculture. Hence, the development of proper strategies and additional research and trials are required. The present review provides an update on recent developments in the use of PGPRs in soilless agriculture, examining these bacteria from different perspectives in an attempt to generate critical discussion and aid in the understanding of the interaction between soilless agriculture and PGPRs.