The capacity of microbes to degrade recalcitrant materials has been extensively explored for environmental remediation and industrial production. Significant achievements have been made with single ...strains, but focus is now going toward the use of microbial consortia owning to their functional stability and efficiency. However, assembly of simplified microbial consortia (SMC) from complex environmental communities is still far from trivial due to large diversity and the effect of biotic interactions. Here we propose a strategy, based on enrichment and dilution-to-extinction cultures, to construct SMC with reduced diversity for degradation of keratinous materials. Serial dilutions were performed on a keratinolytic microbial consortium pre-enriched from a soil sample, monitoring the dilution effect on community growth and enzymatic activities. An appropriate dilution regime (10
) was selected to construct a SMC library from the enriched microbial consortium. Further sequencing analysis and keratinolytic activity assays demonstrated that obtained SMC displayed actual reduced microbial diversity, together with various taxonomic composition, and biodegradation capabilities. More importantly, several SMC possessed equivalent levels of keratinolytic efficiency compared to the initial consortium, showing that simplification can be achieved without loss of function and efficiency. This methodology is also applicable to other types of recalcitrant material degradation involving microbial consortia, thus considerably broadening its application scope.
Biofilm is ubiquitous in industrial water systems, causing biofouling and leading to heat transfer efficiency decreases. In particular, multi-species living in biofilms could boost biomass production ...and enhance treatment resistance. In this study, a total of 37 bacterial strains were isolated from a cooling tower biofilm where acetic acid and propionic acid were detected as the main carbon sources. These isolates mainly belonged to
Proteobacteria
and
Firmicutes
, which occupied more than 80% of the total strains according to the 16S rRNA gene amplicon sequencing. Four species (
Acinetobacter
sp. CTS3,
Corynebacterium
sp. CTS5,
Providencia
sp. CTS12, and
Pseudomonas
sp. CTS17) were observed co-existing in the synthetic medium. Quantitative comparison of biofilm biomass from mono- and multi-species showed a synergistic effect towards biofilm formation among these four species. Three metabolic inhibitors (sulfathiazole, 3-bromopyruvic acid, and 3-nitropropionic acid) were employed to prevent biofilm formation based on their inhibitory effect on corresponding metabolic pathways. All of them displayed evident inhibition profiles to biofilm formation. Notably, combining these three inhibitors possessed a remarkable ability to block the multi-species biofilm development with lower concentrations, suggesting an enhanced effect appeared in simultaneous use. This study demonstrates that combined utilization of metabolic inhibitors is an alternative strategy to prevent multi-species biofilm formation.
Key Points
37 bacterial strains were isolated and identified from a cooling tower biofilm.
Synergistic effect of biofilm formation was observed among four species.
Three metabolic inhibitors showed effective inhibition against biofilm formation.
Targeting cellular metabolism is an effective way to inhibit biofilm formation.
This study investigated the impact of different preheat treatments on the emulsifying and gel textural properties of soy protein with varying 11S/7S ratios. A mixture of 7S and 11S globulins, ...obtained from defatted soybean meal, was prepared at different ratios. The mixed proteins were subjected to preheating (75 °C, 85 °C, and 95 °C for 5 min) or non-preheating, followed by spray drying or non-spray drying. The solubility of protein mixtures rich in the 7S fraction tended to decrease significantly after heating at 85 °C, while protein mixtures rich in the 11S fraction showed a significant decrease after heating at 95 °C. Surprisingly, the emulsion stability index (ESI) of protein mixtures rich in the 7S fraction significantly improved twofold during processing at 75 °C. This study revealed a negative correlation between the emulsifying ability of soy protein and the 11S/7S ratio. For protein mixtures rich in either the 7S or the 11S fractions, gelling proprieties as well as emulsion activity index (EAI) and ESI showed no significant changes after spray drying; however, surface hydrophobicity was significantly enhanced following heating at 85 °C post-spray drying treatment. These findings provide insights into the alterations in gelling and emulsifying properties during various heating processes, offering great potential for producing soy protein ingredients with enhanced emulsifying ability and gelling property. They also contribute to establishing a theoretical basis for the standardized production of soy protein isolate with specific functional characteristics.
A promising keratin-degrading strain from the genus Chryseobacterium (Chryseobacterium sp. KMC2) was investigated using comparative genomic tools against three publicly available reference genomes to ...reveal the keratinolytic potential for biosynthesis of valuable secondary metabolites. Genomic features and metabolic potential of four species were compared, showing genomic differences but similar functional categories. Eleven different secondary metabolite gene clusters of interest were mined from the four genomes successfully, including five common ones shared across all genomes. Among the common metabolites, we identified gene clusters involved in biosynthesis of flexirubin-type pigment, microviridin, and siderophore, showing remarkable conservation across the four genomes. Unique secondary metabolite gene clusters were also discovered, for example, ladderane from Chryseobacterium sp. KMC2. Additionally, this study provides a more comprehensive understanding of the potential metabolic pathways of keratin utilization in Chryseobacterium sp. KMC2, with the involvement of amino acid metabolism, TCA cycle, glycolysis/gluconeogenesis, propanoate metabolism, and sulfate reduction. This work uncovers the biosynthesis of secondary metabolite gene clusters from four keratinolytic Chryseobacterium species and shades lights on the keratinolytic potential of Chryseobacterium sp. KMC2 from a genome-mining perspective, can provide alternatives to valorize keratinous materials into high-value bioactive natural products.
Non-grain production of cultivated land (NGPOCL), as a severe threat to food security, has attracted great attention in China and other countries of the world. Although some scholars have focused on ...the NGPOCL, few studies performed the analysis at the plot scale across the whole region. This study takes Guanzhong Region as the study area and carries out a comprehensive analysis of NGPOCL according to the framework of "phenomenon-cause-countermeasure". According to the land-use map, the range of cultivated land was delineated; based on the 16-day time resolution MODIS vegetation index data, the NGPOCL range was further extracted from the cultivated land by distinguishing the grain/non-grain crops according to their seasonal variation characteristics on the vegetation index. Some spatial statistical methods were used to analyze the spatial-temporal characteristics of NGPOCL in the study area from 2000 to 2018, and it was observed as follows. Firstly, the NGPOCL problem in Guanzhong Region was getting worse during the study period, and the NGPOCL severity and area increased by 10.79% and 31.30% respectively. Secondly, the NGPOCL process showed significant temporal and spatial heterogeneity. The gravity center for NGPOCL was gradually shifted from Chunhua County to Xi'an City in the southeast. Meanwhile, the spatial autocorrelation of NGPOCL was weakening, and Moran' I was declining year by year. These indicated that the NGPOCL had been fully rolled out in the Guanzhong Region, and it had evolved from the past adjacent expansion to the current full bloom. As for the driving mechanism, while those natural factors determined the skeleton of the NGPOCL pattern, social and economic factors played an important role in the evolution process following, and different industrial policies have dominated the NGPOCL expansion at different stages. In the future, it is necessary to pay attention to the impact of industrial policies on NGPOCL and consider the demands of urbanization for non-grain agricultural products properly, so as to develop the characteristic agricultural products industry in a reasonable and compliant manner.
•Range for non-grain production of cultivated land (NGPOCL) in region scale was mapped.•NGPOCL in Guanzhong Region was getting worse but with a slowed-down speed.•Spatiotemporal heterogeneity of NGPOCL was studied by GIS and Spatial Statistics.•NGPOCL was fully rolled out in the study area, and its driving mechanism also changed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Keratin is an insoluble fibrous protein from natural environments, which can be recycled to value-added products by keratinolytic microorganisms. A microbial consortium with efficient keratinolytic ...activity was previously enriched from soil, but the genetic basis behind its remarkable degradation properties was not investigated yet. To identify the metabolic pathways involved in keratinolysis and clarify the observed synergy among community members, shotgun metagenomic sequencing was performed to reconstruct metagenome-assembled genomes. More than 90% genera of the enriched bacterial consortium were affiliated to Chryseobacterium, Stenotrophomonas, and Pseudomonas. Metabolic potential and putative keratinases were predicted from the metagenomic annotation, providing the genetic basis of keratin degradation. Furthermore, metabolic pathways associated with keratinolytic processes such as amino acid metabolism, disulfide reduction and urea cycle were investigated from seven high-quality metagenome-assembled genomes, revealing the potential metabolic cooperation related to keratin degradation. This knowledge deepens the understanding of microbial keratinolytic mechanisms at play in a complex community, pinpointing the significance of synergistic interactions, which could be further used to optimize industrial keratin degradation processes.
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•Metagenome of an efficient keratin-degrading bacterial consortium was sequenced.•Metabolic potential of this bacterial consortium was uncovered.•Novel putative keratinases of interests were retrieved from the metagenome.•High-quality MAGs were obtained to unravel potential metabolic cooperation.•Microbial keratinolytic mechanisms were revealed from a genomic perspective.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Successful enrichment of a novel microbial consortium for keratin valorization.•The consortium displays a high keratinolytic activity and reproducibility.•Residual keratin has low nutrient content, ...limiting further bioconversion.•The bioconversion process favors releasing of low sulphur-containing protein.
Keratin refers to a group of insoluble and recalcitrant protein materials. Slaughterhouses produce large amount of keratinous byproducts, which are either disposed or poorly valorized through costly thermochemical processes for animal feed formulation. Learning from nature, keratinolytic microbial consortia stand as a cost-efficient and environmental friendly way to valorize this recalcitrant resource. Directed selection was applied to enrich soil-born microbial consortia, using sequential batch cultivations in keratin medium, while measuring enzymes activity and monitoring consortia compositions via 16S rRNA gene amplicon sequencing. A promising microbial consortium KMCG6, featuring mainly members of Bacteroidetes and Proteobacteria, was obtained. It possessed keratinolytic activity with <25% residual substrate remaining, which also displayed a high degradation reproducibility level after long-term cryopreservation. This work represents an advance in the field of α-keratin degradation with potential for practical applications.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Abstract The capacity of microbes degrading recalcitrant materials has been extensively explored from environmental remediation to industrial applications. Although significant achievements were ...obtained with single strains, focus is now going toward the use of microbial consortia because of advantages in terms of functional stability and efficiency. While consortia assembly attempts were made from several known single strains, another approach consists in obtaining consortia from complex environmental microbial communities in search for novel microbial species, genes and functions. However, assembling efficient microbial consortia from complex environmental communities is far from trivial due to large diversity and biotic interactions at play. Here we propose a strategy containing enrichment and dilution-to-extinction cultures to construct simplified microbial consortia (SMC) for keratinous waste management, from complex environmental communities. Gradual dilutions were performed from a keratinolytic microbial consortium, and dilution 10 −9 was selected to construct a SMC library. Further compositional analysis and keratinolytic activity assays demonstrated that microbial consortia were successfully simplified, without impacting their biodegradation capabilities. These SMC possess promising potential for efficient keratinous valorization. More importantly, this reasoning and methodology could be transferred to other topics involving screening for simplified communities for biodegradation, thus considerably broadening its application scope. Importance Microbial consortia have got more and more attention and extensive applications due to their potential advantages. However, a high diversity of microbes is likely to hide uncontrollable risks in practice specific to novel strains and complicated interaction networks. Exploring a convenient and efficient way to construct simplified microbial consortia is able to broaden the applied scope of microbes. This study presents the approach based on enrichment and dilution-to-extinction cultures, which gain abundance microbial consortia including some without losing efficiency from the enriched functional microbial community. The microbial interactions at the strain level were evaluated by using compositional identification and correlation analysis, which contribute to revealing the roles of microbes in the degradation process of recalcitrant materials. Our findings provide a systematic scheme to achieve optimizing microbial consortia for biodegradation from an environmental sample, could be readily applied to a range of recalcitrant materials management from environmental remediation to industrial applications.
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