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Applied and Environmental Microbiology Nov 2022With industrial agriculture increasingly challenging our ecological limits, alternative food production routes such as microbial protein (MP) production are receiving...
With industrial agriculture increasingly challenging our ecological limits, alternative food production routes such as microbial protein (MP) production are receiving renewed interest. Among the multiple substrates so far evaluated for MP production, renewable bioethanol (EtOH) is still underexplored. Therefore, the present study investigated the cultivation of five microorganisms (2 bacteria, 3 yeasts) under carbon (C), nitrogen (N), and dual C-N-limiting conditions (molar C/N ratios of 5, 60, and 20, respectively) to evaluate the production (specific growth rate, protein and biomass yield, production cost) as well as the nutritional characteristics (protein and carbohydrate content, amino acid [AA] profile) of MP production from bioethanol. Under C-limiting conditions, all the selected microorganisms showed a favorable AA profile for human nutrition (average AA score of 1.5 or higher), with a negative correlation between protein content and growth rate. Maximal biomass yields were achieved under conditions where no extracellular acetate was produced. Cyberlindnera saturnus and Wickerhamomyces anomalus displayed remarkably high biomass yields (0.40 to 0.82 g cell dry weight [CDW]/g EtOH), which was reflected in the lowest estimated biomass production costs when cultivated with a C/N ratio of 20. Finally, when the production cost was evaluated on a protein basis, Corynebacterium glutamicum grown under C-limiting conditions showed the most promising economic outlook. The global protein demand is rapidly increasing at rates that cannot be sustained, with projections showing 78% increased global protein needs by 2050 (361 compared to 202 million ton/year in 2017). In the absence of dedicated mitigation strategies, the environmental effects of our current food production system (relying on agriculture) are expected to surpass the planetary boundaries-the safe operating space for humanity-by 2050. Here, we illustrate the potential of bioethanol-renewable ethanol produced from side streams-as a main resource for the production of microbial protein, a radically different food production strategy in comparison to traditional agriculture, with the potential to be more sustainable. This study unravels the kinetic, productive, and nutritional potential for microbial protein production from bioethanol using the bacteria Methylorubrum extorquens and Corynebacterium glutamicum and the yeasts Cyberlindnera saturnus, and Metschnikowia pulcherrima, setting the scene for microbial protein production from renewable ethanol.
Topics: Humans; Nitrogen; Carbon; Biomass; Ethanol; Yeasts; Fermentation; Biofuels
PubMed: 36286523
DOI: 10.1128/aem.01188-22 -
Scientific Reports Oct 2022Due to the co-evolved intricate relationships and mutual influence between changes in the microbiome and silage fermentation quality, we explored the effects of...
Due to the co-evolved intricate relationships and mutual influence between changes in the microbiome and silage fermentation quality, we explored the effects of Lactobacillus plantarum and Propionibacterium acidipropionici (Inoc1) or Lactobacillus buchneri (Inoc2) inoculants on the diversity and bacterial and fungal community succession of rehydrated corn (CG) and sorghum (SG) grains and their silages using Illumina Miseq sequencing after 0, 3, 7, 21, 90, and 360 days of fermentation. The effects of inoculants on bacterial and fungal succession differed among the grains. Lactobacillus and Weissella species were the main bacteria involved in the fermentation of rehydrated corn and sorghum grain silage. Aspergillus spp. mold was predominant in rehydrated CG fermentation, while the yeast Wickerhamomyces anomalus was the major fungus in rehydrated SG silages. The Inoc1 was more efficient than CTRL and Inoc2 in promoting the sharp growth of Lactobacillus spp. and maintaining the stability of the bacterial community during long periods of storage in both grain silages. However, the bacterial and fungal communities of rehydrated corn and sorghum grain silages did not remain stable after 360 days of storage.
Topics: Agricultural Inoculants; Edible Grain; Fermentation; Microbiota; Silage; Sorghum; Zea mays
PubMed: 36207495
DOI: 10.1038/s41598-022-21461-4 -
Microbiology Spectrum Oct 2022This study determined the composition of fungal communities and characterized the enriched fungal species in raw and roasted malts via the third-generation PacBio-based...
This study determined the composition of fungal communities and characterized the enriched fungal species in raw and roasted malts via the third-generation PacBio-based full-length single-molecule real-time (SMRT) sequencing of the full-length amplicon of the internal transcribed spacer (ITS) region. In total, one kingdom, six phyla, 23 classes, 56 orders, 120 families, 188 genera, 333 species, and 780 operational taxonomic units (OTUs) were detected with satisfactory sequencing depth and sample size. Wickerhamomyces (56%), Cyberlindnera (15%), Dipodascus (12%), and Candida (6.1%) were characterized as the dominant genera in the raw malts, and Aspergillus (35%), Dipodascus (21%), Wickerhamomyces (11%), and Candida (3.5%) in the roasted malts. Aspergillus proliferans, Aspergillus penicillioides, and Wickerhamomyces anomalus represented the crucial biomarkers causing intergroup differences. Correlation analysis regarding environmental factors indicated that the water activity (a) of the samples affected the composition of the fungal communities in the malts. In practice, special attention should be paid to the mycotoxin-producing fungi, as well as other fungal genera that are inversely correlated with their growth, to ensure the safe use of malt and its end products. Fungal contamination and secondary metabolite accumulation in agricultural products represent a global food safety challenge. Although high-throughput sequencing (HTS) is beneficial for explaining fungal communities, it presents disadvantages, such as short reads, species-level resolution, and uncertain identification. This work represents the first attempt to characterize the fungal community diversity, with a particular focus on mycotoxin-producing fungi, in malt via the third-generation PacBio-based full-length SMRT sequencing of the ITS region, aiming to explore and compare the differences between the fungal communities of raw and roasted malts. The research is beneficial for developing effective biological control and conservation measures, including improving the roasting conditions, monitoring the environmental humidity and a, and effectively eliminating and degrading fungi in the industry chain according to the diverse fungal communities determined, for the safe use of malts and their end products, such as beers. In addition, the third-generation SMRT sequencing technology allows highly efficient analysis of fungal community diversity in complex matrices, yielding fast, high-resolution long reads at the species level. It can be extended to different research fields, updating modern molecular methodology and bioinformatics databases.
Topics: Humans; Mycobiome; Fungi; High-Throughput Nucleotide Sequencing; Mycotoxins; Water
PubMed: 36154437
DOI: 10.1128/spectrum.00511-22 -
Frontiers in Microbiology 2022Grapes harbour a plethora of non-conventional yeast species. Over the past two decades, several of the species have been extensively characterised and their contribution...
Grapes harbour a plethora of non-conventional yeast species. Over the past two decades, several of the species have been extensively characterised and their contribution to wine quality is better understood. Beyond fermentation, some of the species have been investigated for their potential as alternative biological tools to reduce grape and wine spoilage. However, such studies remain limited to a few genera. This work aimed to evaluate the antagonistic activity of grape must-derived non-conventional yeasts against and bunch-rotting moulds and to further elucidate mechanisms conferring antifungal activity. A total of 31 yeast strains representing 21 species were screened on different agar media using a dual culture technique and liquid mixed cultures, respectively. was the most potent with a minimum inhibitory concentration of 10 cells/mL against but it had a narrow activity spectrum. Twelve of the yeast strains displayed broad antagonistic activity, inhibiting three strains of (B05. 10, IWBT FF1 and IWBT FF2), a strain of and Production of chitinases and glucanases in the presence of was a common feature in most of the antagonists. Volatile and non-volatile compounds produced by antagonistic yeast strains in the presence of were analysed and identified using gas and liquid chromatography mass spectrometry, respectively. The volatile compounds identified belonged mainly to higher alcohols, esters, organosulfur compounds and monoterpenes while the non-volatile compounds were cyclic peptides and diketopiperazine. To our knowledge, this is the first report to demonstrate inhibitory effect of the non-volatile compounds produced by various yeast species.
PubMed: 36081805
DOI: 10.3389/fmicb.2022.986229 -
Foods (Basel, Switzerland) Aug 2022Physicochemical changes in fermented alcoholic beverages are significantly related to microbial community development during fermentation. Due to its unusually long...
Physicochemical changes in fermented alcoholic beverages are significantly related to microbial community development during fermentation. Due to its unusually long fermentation, , a traditional Korean house rice wine fermented with as the traditional starter, gives rise to a strong yeast community and, therefore, a high ethanol concentration and different flavors. However, no detailed analysis has been examined. Changes in microbial community structure during fermentation were examined using both culture-dependent and culture-independent methods. During fermentation, and were dominant during all stages of the fermentation. In contrast, Candida , , , and were identified as minor. appeared after the second brewing and then remained constant. Among the 19 compounds identified in this study as order-active compounds, 2-methyl-1-butanol (isoamyl alcohol) was the major compound that increased during the long fermentation stage. Most of the odor-active compounds such as 2,3-butanediol, 3-methyl-1-butanol, ethyl tetradecanoate, ethyl decanoate, ethyl dodecanoate, butanoic acid, 3-methylbutanoic acid (isovaleric acid), 2-methylbutanoic acid, 2-methyl-1-propanol, ethyl acetate, ethyl caprylate, 2-phenylethanol, and 3-methylbutyl acetate increased as the fermentation progressed during 68 days of fermentation, which showed significant differences in the concentrations of odor-active compounds of commercially fermented .
PubMed: 36076792
DOI: 10.3390/foods11172604 -
Microbial Cell Factories Sep 2022D-Arabitol, a five-carbon sugar alcohol, represents a main target of microbial biorefineries aiming to valorize cheap substrates. The yeast Wickerhamomyces anomalus WC...
BACKGROUND
D-Arabitol, a five-carbon sugar alcohol, represents a main target of microbial biorefineries aiming to valorize cheap substrates. The yeast Wickerhamomyces anomalus WC 1501 is known to produce arabitol in a glycerol-based nitrogen-limited medium and preliminary fed-batch processes with this yeast were reported to yield 18.0 g/L arabitol.
RESULTS
Fed-batch fermentations with W. anomalus WC 1501 were optimized using central composite design (CCD). Dissolved oxygen had not a significant effect, while optimum values were found for glycerol concentration (114.5 g/L), pH (5.9), and temperature (32.5 °C), yielding 29 g/L D-arabitol in 160 h, a conversion yield of 0.25 g of arabitol per g of consumed glycerol, and a volumetric productivity of 0.18 g/L/h. CCD optimal conditions were the basis for further improvement, consisting in increasing the cellular density (3✕), applying a constant feeding of glycerol, and increasing temperature during production. The best performing fed-batch fermentations achieved 265 g/L D-arabitol after 325 h, a conversion yield of 0.74 g/g, and a volumetric productivity of 0.82 g/L/h.
CONCLUSION
W. anomalus WC 1501 confirmed as an excellent producer of D-arabitol, exhibiting a remarkable capability of transforming pure glycerol. The study reports among the highest values ever reported for microbial transformation of glycerol into D-arabitol, in terms of arabitol titer, conversion yield, and productivity.
Topics: Glucose; Glycerol; Saccharomycetales; Sugar Alcohols
PubMed: 36058916
DOI: 10.1186/s12934-022-01898-y -
Foods (Basel, Switzerland) Jul 2022The use of non- yeasts in brewing is a useful tool for developing new products to meet the growing consumer demand for innovative products. Non- yeasts can be used both...
The use of non- yeasts in brewing is a useful tool for developing new products to meet the growing consumer demand for innovative products. Non- yeasts can be used both in single and in mixed fermentations with , as they are able to improve the sensory profile of beers, and they can be used to obtain functional beers (with a low ethanol content and melatonin production). The aim of this study was to evaluate this capacity in eight non- strains isolated from Madrid agriculture. For this purpose, single fermentations were carried out with non- strains and sequential fermentations with non- and the commercial strain SafAle S-04. The strain CLI 1028 was selected in pure culture for brewing beer with a low ethanol content (1.25% (/)) for its fruity and phenolic flavours and the absence of wort flavours. The best-evaluated strains in sequential fermentation were CLI 3 () and CLI 457 (), due to their fruity notes as well as their superior bitterness, body, and balance. Volatile compounds and melatonin production were analysed by GC and HPLC, respectively. The beers were sensory-analysed by a trained panel. The results of the study show the potential of non- strains in the production of low-alcohol beers, and as a flavour enhancement in sequential fermentation.
PubMed: 35885271
DOI: 10.3390/foods11142029 -
Foods (Basel, Switzerland) Jun 2022A new method was proposed to produce alginate bio-films containing and killer yeast to control the post-harvest fungal decay in organic apples caused by and ....
A new method was proposed to produce alginate bio-films containing and killer yeast to control the post-harvest fungal decay in organic apples caused by and . Coatings with killer yeast effectively controlled the growth of during storage at 22 °C. killer yeast incorporated in alginate reduced the incidence from 90% (control) to 35% after 14 days of storage at 22 °C. Alginate biofilms with or also limited the incidence of the fungal decay of apples inoculated with compared with the control fruits, although the antagonistic capability against was lower than against . The survival of cells in alginate coating was higher than . The incorporation of killer yeasts into alginate had no significant effect on the mechanical properties (tensile strength, percent elongation at break) of alginate coating, however, they increased the thickness of the biofilm. The bioactive coating reduced the fruit weight loss and had no significant effects on the fruit firmness during storage at 2 °C. As organic apples, produced without any synthetic fungicides, are especially prone to fungal decay during storage, the proposed alginate biofilms containing killer yeast seem to be a very promising solution by offering non-chemical, biological control of post-harvest pathogens.
PubMed: 35804682
DOI: 10.3390/foods11131868 -
Frontiers in Physiology 2022Management of the rice brown planthopper Stål is challenging because it can rapidly adapt to new pesticides within several generations. Combined use of chemical...
Management of the rice brown planthopper Stål is challenging because it can rapidly adapt to new pesticides within several generations. Combined use of chemical insecticides and antimicrobials was proposed as an alternative strategy to control . Our previous experiments identified two effective agents (chemical insecticide: pymetrozine and antimicrobial: zhongshengmycin) that act on different targets in . However, conditions and effectiveness of combinations of antimicrobials and insecticides against are still unknown. Here, we evaluated separate and combined effects of pymetrozine and zhongshengmycin on third instar nymphs of under laboratory and greenhouse conditions. Results showed that zhongshengmycin exerts significant inhibitory effects on the three endosymbionts , , and cultured of . Combinations of pymetrozine and zhongshengmycin under laboratory conditions produced additive or synergistic effects on and caused higher mortality in third instar nymphs than either of them used alone. Experiments under greenhouse conditions further demonstrated that effective component quality ratio of pymetrozine to zhongshengmycin of 1:10 and 1:40 with co-toxicity coefficients of 221.63 and 672.87, respectively, also produced significant synergistic effects against . Our results indicated that chemical insecticides combined with antimicrobials may provide a potential novel strategy for controlling by inhibiting its endosymbionts.
PubMed: 35707007
DOI: 10.3389/fphys.2022.875610 -
3 Biotech Jul 2022The purpose of this research was to isolate microorganisms from coffee fermentation processes and screen them for their potential to improve the flavor of Arabica coffee...
The purpose of this research was to isolate microorganisms from coffee fermentation processes and screen them for their potential to improve the flavor of Arabica coffee using a new approach that included pectin degradation ability and growth in mucilage broth. All of the studied microorganisms were isolated from 38 different samples of fresh coffee cherries, coffee mucilage and coffee pulp. A total of 262 microbial isolates were obtained and subjected to screening using pectinase screening agar medium for pectinolytic organisms. The results of the pectinase production test showed that 18 yeast isolates were found to produce pectinase that could degrade the pectin present in solid media. The sugar assimilation profiles and growth of selected strains in mucilage broth were studied. Therefore, 18 isolates from the selected yeasts were subjected to molecular identification by the use of 18S rRNA gene sequencing. The diversity of the yeast isolates was studied, and they were identified as , , and sp. Moreover, isolates SWU3YWP1-3, SWU3YSK9 and INFCY1-4 were used as a seed culture for Arabica coffee fermentation. The cupping sensory scores of the control (without yeast inoculation) and those inoculated with three isolated yeast strains that were determined by Q-Arabica Graders were 73.75, 84.75, 80.25 and 75.00, respectively. Unique flavors and aromas were detected. This is the first report of screening microorganisms from the Arabica coffee fermentation process by the combination of various properties with success in improving the quality of coffee beverage.
PubMed: 35685951
DOI: 10.1007/s13205-022-03203-5