Optimal Fermentation Research Articles

Preparation, flavor component and antioxidant activity analysis of Lactiplantibacillus plantarum NCU137 fermented rice protein

Rice protein is the main component in the byproducts of rice processing such as rice dregs and rice bran. This study aims to develop lactic acid bacteria-fermented rice protein and analyze the changes of component and bioactivity. Lactiplantibacillus plantarum NCU137 was selected as the optimum fermentation strain from sixty lactic acid bacteria strains using fermentation performance and sensory score as the criteria. NCU137 was then applied to rice protein fermentation and the process parameters were optimized by single factor and orthogonal experiments. NCU137 fermentation significantly increased the acidity, antioxidant activity, and peptide content of rice protein, and eight volatile flavor compounds were identified as characteristic aroma components as determined by SPME-GC-MS. Of them, the OAV value of 1-hexanol was up to 50.94, contributing the most to the flavor of fermented rice protein. Furthermore, the antioxidant activity and mechanism of rice protein antioxidant peptide (RPAP) on H2O2-induced Caco-2 cell damage were investigated by CCK-8 method and fluorescence microscopy. RPAP showed protective effect on cell damage in a dose-dependent manner, accompanying by reduction of oxidative components such as ROS and MDA, and increasement of antioxidant components such as SOD, CAT, and GSH-PX. The protective effect might lie in the regulation of gene transcription in Nrf2/HO-1 and apoptosis Bax/Bcl pathway, as validated by RT-qPCR assay. Shortly, the rice protein fermented by NCU137 displayed significant improvement of flavor, nutritional components, and antioxidant bioactivity. The fermentation technology provides alternative strategy for processing rice protein in rice dregs and rice bran into high-valued products.

Construction of artificial microbial consortia for efficient degradation of chicken feathers and optimization of degradation conditions.

Microbes within a consortium exhibit a synergistic interaction, enhancing their collective capacity to perform functions more effectively than a single species, especially in the degradation of keratin-rich substrates. To achieve a more stable and efficient breakdown of chicken feathers, a comprehensive screening of over 9,000 microbial strains was undertaken. This meticulous selection process identified strains with the capability to degrade keratin effectively. Subsequently, antagonistic tests were conducted to isolate strains of fungi and bacteria that were non-antagonistic, which were then used to form the artificial microbial consortia. The optimal fermentation conditions for the keratinophilic microbial consortia were determined through the optimization of response surface methodology. The results revealed that 11 microbial strains-comprising of 4 fungi and 7 bacteria-were particularly proficient in degrading chicken feathers. The artificially constructed microbial consortia (AMC) comprised two bacterial strains and one fungal strain. The optimal conditions for feathers degradation were identified as a 10g/L concentration of chicken feathers, a 2.6% microbial inoculation volume and a fermentation fluid pH of 9. Under these conditions, the degradation rate for chicken feathers reached a significant 74.02%, representing an 11.45% increase over the pre-optimization rate. The AMC developed in this study demonstrates the potential for efficient and economical process of livestock and poultry feathers. It provides innovative insights and a theoretical foundation for tackling the challenging degradation of keratin-rich materials. Furthermore, this research lays the groundwork for the separation and purification of keratins, as well as the development of novel proteases, which could have profound implications for a range of applications.

Potential of Dioscorea spp. for Bioethanol Production Using Separate Hydrolysis and Fermentation Method

Thailand is globally recognized for its rich biodiversity, a characteristic that extends to the diverse species of indigenous yams within the Dioscorea spp. genus. With the energy crisis, the selection of agricultural materials for ethanol production to replace the use of economic crops is therefore necessary. This research focuses on six specific yam varieties: Amorphophallus konjac, Colocasia esculenta, Dioscorea bulbifera, Dioscorea alata, Dioscorea hispida, and Dioscorea esculenta. The primary objective is to investigate their bioethanol productivity through the implementation of a separate hydrolysis and fermentation process, with the broader aim of contributing to the potential preservation of these invaluable indigenous yam species. Initiating the study, the experimental samples underwent hydrolysis by alpha-amylase enzyme (1% w/winitial starch) for 180 min, followed by glucoamylase enzyme (1% w/winitial starch) for an additional 72 h. Post the initial hydrolysis, the detection of small molecule sugars by high-performance liquid chromatography, revealed a range of 14.49 ± 1.10 to 28.89 ± 0.03 gtotal sugar/L, with maltose emerging as the predominant sugar compound. Subsequent to the second hydrolysis, it was observed that maltose and starch residues across all six samples underwent successful digestion. The peak glucose productivity was attained at the 12-h mark post-glucoamylase hydrolysis. Among the diverse yam varieties under examination, Dioscorea hispida exhibited the highest glucose production, showcasing a hydrolysis efficiency of 62.53 ± 2.08%. Following the fermentation process with S. cerevisiae, the optimal fermentation time was identified as 72 h, at which point all available glucose in the hydrolysate was fully utilized. The bioethanol productivity spanned from 32.31 ± 3.40 to 43.66 ± 0.02 g/L, with Dioscorea hispida demonstrating the highest ethanol productivity at 0.61 ± 0.00 g/L/h, and a yield of 0.42 ± 0.01 gEtOH/gGlucose. These findings underscore the potential of Dioscorea hispida as a promising contributor to bioethanol production.

Assessing the Impact of Transport Phenomena on Modeling and Optimization of Solid-State Fermentation for the Revalorization of Agro-Industrial Residues in a Wall‐Cooled Packed‐Bed Bioreactor

This work assesses the influence of transport phenomena on the growth of Yarrowia lipolytica 2.2ab (Yl2.2ab) and protease production during Solid-State Fermentation (SSF) in a bench-scale wall-cooled tubular bioreactor packed with substrate-based pellets derived from agro-industrial residues. Our engineering methodology, in a novel manner, includes: (i) developing a new pseudo-heterogeneous model, (ii) identifying and quantifying the impact of all transport phenomena on microbial kinetics, (iii) elucidating how fluid dynamics enhances heat and mass transfer processes, and hence microbial kinetics, and (iv) determining the operational and geometric parameters for optimal bioreactor performance. As main results: (i) all transport phenomena occurring within the bench-scale bioreactor are fundamental for its reliable simulation and will be essential for its scale-up, and (ii) the maximum production of proteases, 420 U kgDS‐1−1, is achieved under the following operational conditions: a tube to particle diameter ratio of 5.6, a bath temperature of 45°C, an inlet airflow rate of 1 L min−1, and inlet fluid temperature of 43 °C. Finally, the pseudo-heterogeneous model is assessed by describing SSF-based observations from the literature, appropriately predicting the performance of Yl2.2ab in a bench-scale bioreactor. These results pave the way for future exploration of Yl2.2ab in SSF within larger-scale packed-bed bioreactors.

Role of AplaeA in the regulation of spore production and poly(malic acid) synthesis in Aureobasidium pullulans

Poly(malic acid) (PMLA) as one of the important metabolites in Aureobasidium pullulans has great application in a variety of fields. LaeA, a global regulator capable of controlling fungal secondary metabolites, has been identified in A. pullulans. The involvement of LaeA in the biosynthesis of PMLA through direct or indirect means and its role in A. pullulans is currently unknown. Here we extracted and characterized the AplaeA gene from A. pullulans HIT-LCY3T and resolved it by bioinformatics. The function of AplaeA was subsequently characterized by Rnai-LaeA and OEX-LaeA mutants. Based on phenotypic observations of the mutant strains, it was found that the gene had a large effect on the morphology and melanin production aspects of the strain, and that overexpression of the AplaeA gene resulted in a substantial increase in spore numbers. RT-qPCR combined with protein interactions results analyzed that ApLaeA positively regulates PMLA biosynthesis by controlling the expression of core genes of PMLA biosynthesis gene cluster and other related regulatory factors. Finally, OEX-LaeA was used as the starting strain to obtain the optimal fermentation conditions. These findings illustrate the regulatory mechanism of a hypothesized global regulator, LaeA, in A. pullulans HIT-LCY3T, suggesting its potential application in industrial-scale PMLA biosynthesis.

Evaluating the Impact of Green Coffee Bean Powder on the Quality of Whole Wheat Bread: A Comprehensive Analysis.

The current investigation focuses on the effect of different concentrations of green coffee bean powder (GCBp) on the physicochemical, microbiological, and sensory characteristics of whole wheat bread (WWB). C1 bread formulation (containing 1% GCBp) exhibited the highest loaf volume, suggesting optimal fermentation. Moisture analysis revealed minor alterations in the moisture retention attributes of the bread formulations. Impedance analysis suggested that C1 exhibited the highest impedance with a high degree of material homogeneity. Swelling studies suggested similar swelling properties, except C5 (containing 5% GCBp), which showed the lowest swelling percentage. Furthermore, color and microcolor analysis revealed the highest L* and WI in C1. Conversely, higher concentrations of GCBp reduced the color attributes in other GCBp-containing formulations. FTIR study demonstrated an improved intermolecular interaction in C1 and C2 (containing 2% GCBp) among all. No significant variation in the overall textural parameters was observed in GCBp-introduced formulations, except C2, which showed an improved gumminess. Moreover, the TPC (total phenolic content) and microbial analysis revealed enhanced antioxidant and antimicrobial properties in GCBp-incorporated formulations compared to Control (C0, without GCBp). The sensory evaluation showed an enhanced appearance and aroma in C1 compared to others. In short, C1 showed better physicochemical, biological, and sensory properties than the other formulations.

Exploring the Impact of Fermentation Time and Climate on Quality of Cocoa Bean-Derived Chocolate: Sensorial Profile and Volatilome Analysis.

The market for fine-flavor cocoa provides significant benefits to farmers. However, identifying the sensory qualities of chocolate under specific environmental conditions and measuring how its chemical compounds may be affected by climate differences and postharvesting practices remain a challenge. This study investigates how fermentation time and agroclimatic conditions in Colombia's fine cocoa-producing region of Arauca influence the sensory profile and volatile compound composition (volatilome) of chocolate derived from cocoa beans. Sensory evaluation was conducted on chocolates fermented for 48, 72, 96, and 120 h, revealing that fermentation time critically affects the development of fine-flavor attributes, particularly fruitiness and nuttiness. The optimal fermentation period to enhance these attributes was identified at 96 h, a duration consistently associated with peak fruitiness under all studied climatic conditions. Analysis of 44 volatile compounds identified several key aroma markers, such as acetoin, 1-methoxy-2-propyl acetate, and various pyrazines, which correlate with desirable sensory attributes. These compounds exhibited varying amounts depending on fermentation time and specific agroclimatic conditions, with a 96 h fermentation yielding chocolates with a higher quantity of volatile compounds associated with preferred attributes. Our findings highlight the complex interaction between fermentation processes and agroclimatic factors in determining cocoa quality, providing new insights into optimizing the flavor profiles of chocolate.

Revealing the optimal traditional processing methods and its protective effects against febrile seizures of Arisaema cum bile.

Arisaema cum bile (known as Dan Nanxing in Chinese, DNX) is a herbal medicine used for treating febrile seizure (FS), which commonly prepared by using Arisaematis Rhizoma and animal bile. This study was designed to explore the optimal processing time of DNX and its potential mechanism on the anti-FS effect. A total of 17 volatile organic compounds (VOCs) were the characteristic ones to distinguish different fermentation stages of DNX by using gas chromatography-ion mobility spectrometry (GC-IMS), such as 2-heptanone monomer, and heptanal monomer. DNX with fermentation for 3 months had an obvious pattern of VOCs with others, which could be regarded as the optimal fermentation time. The Enterococcus and Staphylococcus might be the core bacteria on the production of VOCs. Additionally, DNX (2.8 g/kg, p.o.) reversed hot water bath-induced FSs of rats, as indicated by increased seizure latency and decreased seizure duration time. It also prevented hippocampal neuronal loss, increased GABAAR, and decreased GRIA1 expression. At the genus level, relative abundance of Enterococcus and Akkermansia were enriched after DNX treatment. These findings suggested that fermentation for 3 months might be the optimal process time for DNX, and DNX possess an anti-FS effect through regulating neurotransmitter disorder and gut microbiota.

Unraveling the Potential of γ-Aminobutyric Acid: Insights into Its Biosynthesis and Biotechnological Applications.

γ-Aminobutyric acid (GABA) is a widely distributed non-protein amino acid that serves as a crucial inhibitory neurotransmitter in the brain, regulating various physiological functions. As a result of its potential benefits, GABA has gained substantial interest in the functional food and pharmaceutical industries. The enzyme responsible for GABA production is glutamic acid decarboxylase (GAD), which catalyzes the irreversible decarboxylation of glutamate. Understanding the crystal structure and catalytic mechanism of GAD is pivotal in advancing our knowledge of GABA production. This article provides an overview of GAD's sources, structure, and catalytic mechanism, and explores strategies for enhancing GABA production through fermentation optimization, metabolic engineering, and genetic engineering. Furthermore, the effects of GABA on the physiological functions of animal organisms are also discussed. To meet the increasing demand for GABA, various strategies have been investigated to enhance its production, including optimizing fermentation conditions to facilitate GAD activity. Additionally, metabolic engineering techniques have been employed to increase the availability of glutamate as a precursor for GABA biosynthesis. By fine-tuning fermentation conditions and utilizing metabolic and genetic engineering techniques, it is possible to achieve higher yields of GABA, thus opening up new avenues for its application in functional foods and pharmaceuticals. Continuous research in this field holds immense promise for harnessing the potential of GABA in addressing various health-related challenges.

Comparative Transcriptomic Analysis on the Effect of Sesamol on the Two-Stages Fermentation of Aurantiochytrium sp. for Enhancing DHA Accumulation.

Aurantiochytrium is a well-known long-chain polyunsaturated fatty acids (PUFAs) producer, especially docosahexaenoic acid (DHA). In order to reduce the cost or improve the productivity of DHA, many researchers are focusing on exploring the high-yield strain, reducing production costs, changing culture conditions, and other measures. In this study, DHA production was improved by a two-stage fermentation. In the first stage, efficient and cheap soybean powder was used instead of conventional peptone, and the optimization of fermentation conditions (optimal fermentation conditions: temperature 28.7 °C, salinity 10.7‱, nitrogen source concentration 1.01 g/L, and two-nitrogen ratio of yeast extract to soybean powder 2:1) based on response surface methodology resulted in a 1.68-fold increase in biomass concentration. In the second stage, the addition of 2.5 mM sesamol increased the production of fatty acid and DHA by 93.49% and 98.22%, respectively, as compared to the optimal culture condition with unadded sesamol. Transcriptome analyses revealed that the addition of sesamol resulted in the upregulation of some genes related to fatty acid synthesis and antioxidant enzymes in Aurantiochytrium. This research provides a low-cost and effective culture method for the commercial production of DHA by Aurantiochytrium sp.

Postbiotic emissaries: a comprehensive review on the bioprospecting and production of bioactive compounds by Enterococcus species

SummaryEnterococcus species have been acknowledged for their diverse metabolic capabilities, resulting in a wide array of bioactive compounds that show promise for therapeutic use. This article presents a thorough examination of the exploration and synthesis of bioactive compounds by Enterococcus species. It encompasses the taxonomy, natural habitat, and significance in the biotechnology of Enterococcus, emphasising the various bioactive compounds it produces, including antibacterial, immunomodulatory, and antioxidant agents. Strategies for exploring potential bioactivities, encompassing isolation methodologies and screening techniques, are discussed. The biotechnological synthesis of bioactive compounds derived from Enterococcus via fermentation processes, optimisation approaches, and scaling methodologies is expounded. Moreover, the utilisation of these bioactive compounds in functional foods, pharmaceuticals, and agriculture, alongside considerations of safety and regulatory aspects, is examined. The review concludes with future perspectives and challenges in the field of Enterococcus‐derived bioactive compounds.

Identification, fermentation optimization, and biocontrol efficacy of actinomycete YG-5 for the prevention of Alternaria leaf spot disease in star anise

Star anise (Illicium verum), a valuable spice tree, faces significant threats from fungal diseases, particularly Alternaria leaf spot. This study investigates the potential of a soil-derived actinomycete strain, YG-5, as a biocontrol agent against Alternaria tenuissima, the causative pathogen on Alternaria leaf spot in star anise. Through comprehensive morphology, physiology, biochemistry, and genetic analyses, we identified the isolate as Streptomyces sp. YG-5. The strain exhibited broad-spectrum antimicrobial activity against several plant pathogens, with inhibition rates ranging between 36.47 to 80.34%. We systematically optimized the fermentation conditions for YG-5, including medium composition and cultivation parameters. The optimized process resulted in an 89.56% inhibition rate against A. tenuissima, a 14.72% improvement over non-optimized conditions. Notably, the antimicrobial compounds produced by YG-5 demonstrated stability across various temperatures, pH levels, and UV irradiation. In vivo efficacy trials showed promising results, with YG-5 fermentation broth reducing Alternaria leaf spot incidence on star anise leaves by 56.95%. These findings suggest that Streptomyces sp. YG-5 holds significant potential as a biocontrol agent against Alternaria leaf spot in star anise cultivation, offering a sustainable approach to disease management in this valuable crop.

Nitrogen Availability and Utilisation of Oligopeptides by Yeast in Industrial Scotch Grain Whisky Fermentation

Scotch grain whisky is produced with a substantial proportion of unmalted grains, which can result in nitrogen deficiency for yeast in the fermentable grain mash. This study examined nitrogen source availability and utilisation by three commercial whisky strains (Saccharomyces cerevisiae) during Scotch grain whisky fermentation, focusing on oligopeptides. Peptide uptake kinetics in synthetic whisky mash with defined peptides showed that oligopeptides of up to nine amino acids were taken up by the strains, albeit with some variability between the strains. The study found that peptides with appropriate molecular weights could replace free amino acids without negatively affecting fermentation kinetics. Moreover, fermentation performance improved when additional nitrogen was provided via peptides rather than diammonium phosphate. Analysis of industrial grain mash indicated that despite low initial yeast assimilable nitrogen, residual proteolytic activity from malt increased nitrogen availability during fermentation. Approximately 30% of the nitrogen consumed by yeast during grain mash fermentation was derived from peptides. LC-HRMS peptide analysis revealed complex dynamics of peptide formation, degradation, and utilisation. This study highlights the importance of oligopeptides in ensuring optimal fermentation efficiency in Scotch grain mash and similar substrates.

Conjugated Linoleic Acid Production in Pine Nut Oil: A Lactiplantibacillus plantarum Lp-01 Fermentation Approach.

Conjugated linoleic acid (CLA) is a class of bioactive fatty acids that exhibit various physiological activities such as anti-cancer, anti-atherosclerosis, and lipid-lowering. It is an essential fatty acid that cannot be synthesized by the human body and must be derived from dietary sources. The natural sources of CLA are limited, predominantly relying on chemical and enzymatic syntheses methods. Microbial biosynthesis represents an environmentally benign approach for CLA production. Pine nut oil, containing 40-60% linoleic acid, serves as a promising substrate for CLA enrichment. In the present study, we developed a novel method for the production of CLA from pine nut oil using Lactiplantibacillus plantarum (L. plantarum) Lp-01, which harbors a linoleic acid isomerase. The optimal fermentation parameters for CLA production were determined using a combination of single-factor and response surface methodologies: an inoculum size of 2%, a fermentation temperature of 36 °C, a fermentation time of 20 h, and a pine nut oil concentration of 11%. Under these optimized conditions, the resultant CLA yield was 33.47 μg/mL. Gas chromatography analysis revealed that the fermentation process yielded a mixture of c9, t11CLA and t10, c12 CLA isomers, representing 4.91% and 4.86% of the total fatty acid content, respectively.

Optimization and Stability Assessment of Monochamus alternatus Antimicrobial Peptide MaltAtt-1 in Komagataella phaffii GS115 for the Control of Pine Wood Nematode.

MaltAtt-1 is an antimicrobial peptide isolated from Monochamus alternatus with nematocidal activity against pine wood nematode. In this study, a eukaryotic expression system based on Komagataella phaffii GS115 was established, and its secretory expression of MaltAtt-1 was realized. The basic properties and secondary and tertiary structures of the antimicrobial peptide MaltAtt-1 were identified by bioinformatics analysis. MaltAtt-1 is a hydrophilic stable protein, mainly composed of an α-helix (Hh), β-folds (Ee), and irregular curls (Cc). The optimal fermentation conditions for MaltAtt-1 were determined by a single-factor test and the Box-Behnken response surface method, including an induction time of 72 h, induction temperature of 30 °C, culture medium of pH 7.6, methanol volume fraction of 2.0%, and an initial glycerol concentration of 1%. The stability of MaltAtt-1 indicated its resistant to UV irradiation and repeated freezing and thawing, but the antibacterial activity decreased significantly under the influence of high temperature and a strong acid and base, and it decreased significantly to 1.1 cm and 0.83 cm at pH 2.0 and pH 10.0, respectively. The corrected mortality of B. xylophilus achieved 71.94% in 3 h at a concentration of 300 mg·L-1 MaltAtt-1 exposure. The results provide a theoretical basis for the antimicrobial peptide MaltAtt-1 to become a new green and efficient nematicide.

Hybrid Modeling for On-Line Fermentation Optimization and Scale-Up: A Review

Modeling is a crucial tool in the biomanufacturing industry, namely in fermentation processes. This work discusses both mechanistic and data-driven models, each with unique benefits and application potential. It discusses semi-parametric hybrid modeling, a growing field that combines these two types of models for more accurate and easy result extrapolation. The characteristics and structure of such hybrid models will be examined. Moreover, its versatility will be highlighted, showing its usefulness in various stages of process development, including real-time monitoring and optimization. Scale-up remains one of the most relevant topics in fermentation processes, as it is important to have reproducible critical quality attributes, such as titer and yield, on larger scales. Furthermore, the process still relies on empirical correlations and iterative optimization. For these reasons, it is important to improve scale-up predictions, through e.g., the use of digital tools. Perspectives will be presented on the potential that hybrid modeling has by predicting performance across different process scales. This could provide more efficient and reliable biomanufacturing processes that require less resource consumption through experimentation.

Characterization and subcellular localization of selenium in Limosilactobacillus fermentum Ln-9 obtained by intense pulsed light-ultraviolet combined mutagenesis

Lactic acid bacteria (LAB) can convert inorganic selenium (Se) to organic Se and elemental forms with low toxicity and high bioavailability, but a comprehensive Se analysis of Se-enriched LAB is lacking. In this study, Limosilactobacillus fermentum Ln-9 was obtained by intense pulsed light-ultraviolet combined mutagenesis, and its characteristics and subcellular localization of Se were analyzed. The results displayed that Ln-9 accumulated 3.03 times Se that of the original strain. Under optimal fermentation conditions, the total Se content of Se-enriched Ln-9 (SeLn-9) reached 12.16 mg/g with 96.34% contained in Se nanoparticles (SeNPs), which was much higher than that of organic macromolecules. Furthermore, SeNPs were mainly localized outside the cell, Se-proteins were in the membrane and cytoplasmic fractions, and Se-polysaccharides were in the membrane fraction. Besides, SeLn-9 maintained a good morphology and gastrointestinal tolerance and had an enhanced antioxidant capacity. These findings make Ln-9 promising for applications in the food industry.

Physical and chemical properties and sensory evaluation of camel meat and new camel meat jerky.

Alxa Bactrian camel meat is an organic diet that provides balanced nutrition and is easy to digest and absorb. Despite its potential, it is currently underutilized. To develop a new type of camel jerky, this study utilized a single-factor design method to optimize the formula and fermentation process parameters of Alxa Bactrian camel jerky. Additionally, the physical and chemical composition, nutritional components, protein degradation, and microbial changes of the camel jerky were analyzed to evaluate the nutritional benefits of the new camel jerky created using modern fermentation technology. The results show that the optimal addition amounts of camel fermented jerky ingredients are 2.2% black pepper, 3% salt, 1.8% white sugar, and 9% cooking wine, whereas the optimal fermentation conditions by compound starter culture are 0.07% starter, 23 h of fermentation time, and a 30°C fermentation temperature. Compared to the single starter, the compound starter significantly increased the protein content, total amino acids, unsaturated fatty acids, trace elements, and a*, L*, and e-values of jerky; however, it also decreased the water activity (a w), thiobarbituric acid, and pH values of jerky during storage. Compound starter strains can compensate for the shortage of single starters and improve the overall quality of meat products. These findings could provide new insights and serve as a reference for the development of camel meat products and hold significant importance for the growth of the camel industry.

Comparative transcriptomics analysis-guided metabolic engineering of Yarrowia lipolytica for improved erythritol and fructooligosaccharides production

Currently, fructooligosaccharides (FOS) are converted from sucrose by purified enzymes or fungal cells, but these methods are costly and time-consuming. Here, the optimal fermentation conditions for strain E326 were determined through fermentation optimization: initial glucose 200 g/L, NaCl 25 g/L, inoculum volume 20 %, dissolved oxygen 20–30 %, pH 3, and glucose feeding concentration 100 g/L, which increased erythritol titer by 1.5 times. The co-expression of HGT1 and APC11 genes alleviated the erythritol synthesis stagnation, shorten the fermentation time by 16.7 %, and increased the erythritol productivity by 17.2 %. The episomal plasmids based on yeast mitochondrial replication origins (mtORIs) were constructed to surface display fructosyltransferase, effectively utilizing waste yeast cells generated during erythritol fermentation. Under the conditions of 60℃ and pH 6, the FOS yield reached 65 %, which to our best of knowledge is so-far the highest yield of FOS obtained. These findings will contribute to the industrial production of erythritol and FOS.

Enterobacter cloacae Rs-2 inoculum replaces fertiliser application by half in the field and modifies microbial community structure

Using microbial inoculant partial substitution synthetic fertilizer is a new type of environmentally friendly way to significantly improve the corps production and ecological environment. The effects of supplementing Enterobacter cloacae Rs-2 with synthetic fertilizer on the maize growth and soil microbial community diversity in field were investigated in this paper. The optimal fermentation conditions were determined as 5 g·L−1 industrial glucose, 30 g·L−1 industrial peptone, 1 g·L−1 MgSO4 and 0.5 g·L−1 KCl firstly. Field experiment showed that the fresh weight of shoots and roots was increased by 39.69% and 32.46% when half synthetic fertilizer was replaced by microbial inoculant. The soil physical and chemical properties were also greatly improved, especially the contents of available phosphorus, water-soluble calcium and alkali-hydrolyzed nitrogen were significantly increased in T4 (Rs-2 and half chemical fertilizer) and full chemical fertilizer treatment. This result was accompanied by increased the relative abundance of genes related to phospholipid metabolism, phosphotransferase system (PTS) and oxidative phosphorylation metabolism, indicating that Rs-2 may play an important role in the transformation and utilization of phosphorus in soil. The richness, dominance of Proteobacteria, Enterobacteriaceae in the microbial communities were further improved when the microbial inoculant applied. Function prediction PICRUSt analysis indicated that amines and amino acids were the most representative of the total carbon source utilization by the soil microbial communities. It was concluded that the application of 50% of the synthetic fertilizer supplemented with 30 mL microbial inoculant enhanced both the functional diversity of soil microbial communities and maize yield.