Neutral Processes Drive Seasonal Assembly of the Skin Mycobiome.

The importance of microorganisms to human skin health has led to a growing interest in the temporal stability of skin microbiota. Here we investigated the dynamics and assembly of skin fungal communities (mycobiomes) with amplicon sequencing of samples collected from multiple sites on 24 healthy Chinese individuals across four seasons (in the order of winter, spring, summer, and autumn in a calendar year). We found a significant difference in community compositions between individuals, and intrapersonal community variation increased over time at all body sites. Within each season, the frequency of occurrence of most operational taxonomic units (OTUs) was well fitted by a neutral model, highlighting the importance of stochastic forces such as passive dispersal and ecological drift in skin community assembly. Despite the significant richness contributed by neutrally distributed OTUs, skin coassociation networks were dominated by taxa well-adapted to multiple body sites (forehead, forearm, and palm), although hub species were disproportionately rare. Taken together, these results suggest that while skin mycobiome assembly is a predominantly neutral process, taxa that could be under the influence of selective forces (e.g., host selection) are potentially key to the structure of a community network. IMPORTANCE Fungi are well recognized members of the human skin microbiota and are crucial to cutaneous health. Common cutaneous diseases such as seborrheic dermatitis and dermatophytes are linked to fungal species. Most studies related to skin microbial community dynamics have focused on Western subjects, while non-Western individuals are understudied. In this study, we explore the seasonal changes of the skin mycobiome in a healthy Chinese cohort and identify ecological processes that could possibly give rise to such variations. Our work reveals the dynamic nature of host skin fungal community, highlighting the dominant roles neutral forces play in the seasonal assembly of skin mycobiome. This study provides insight into the microbial ecology of the human skin microbiome and fills a knowledge gap in the literature regarding the dynamics of skin fungal community.

Smart Food Waste Recycling Bin (S-FRB) to turn food waste into green energy resources.

Effective treatment of food waste is inherently difficult due to several factors, including its heterogeneous composition, high moisture content, and low heating value. To address these issues, this study aims to convert food waste into an energy resource using naturally occurring fermentative microorganisms embedded in wooden biochips (bio-catalysis), utilizing a "Smart Food Waste Recycling Bin" (S-FRB) system. High-throughput 16S rRNA gene sequencing analysis identified the major aerobic and facultatively anaerobic bacteria with alpha-diversity in terms of the Phylogenetic Diversity index ranging from 40.8 (initial stage) to 24.5 (mature stage), which indicates the microbial communities are relatively homogeneous and effective for use in the S-FBR. Operational results indicated that the organic content of food waste traded in the system increased from 53% up to 72% in the final end-product and achieved a mass reduction rate of approximately 80%. The heating value of the end-product, which was 3300 kcal/kg waste when measured by the differential scanning calorimeter (DSC) method, confirmed its high potential as a biofuel. Overall, the S-FRB system presents a practical approach for food waste treatment that solves the putrescible waste problem and maximizes utility through resource circulation.

Individual and household attributes influence the dynamics of the personal skin microbiota and its association network.

BACKGROUND: Numerous studies have thus far characterized the temporal dynamics of the skin microbiota of healthy individuals. However, there is no information regarding the dynamics of different microbial association network properties. Also, there is little understanding of how living conditions, specifically cohabitation and household occupancy, may be associated with the nature and extent (or degree) of cutaneous microbiota change within individuals over time. In this study, the dynamics of the skin microbiota, and its association networks, on the skin of urban residents over four seasons were characterized. RESULTS: Similar to western cohorts, the individuals of this cohort show different extents of variations in relative abundance of common skin colonizers, concomitant with individual- and household-associated changes in differential abundances of bacterial taxa. Interestingly, the individualized nature of the skin microbiota extends to various aspects of microbial association networks, including co-occurring and excluding taxa, as well as overall network structural properties. Household occupancy is correlated with the extent of variations in relative abundance of Propionibacterium, Acinetobacter, and Bacillus over multiple skin sites. In addition, household occupancy is also associated with the extent of temporal changes in microbial diversity and composition within a resident's skin. CONCLUSIONS: This is the first study investigating the potential roles household occupancy has on the extent of change in one's cutaneous microbiota and its association network structures. In particular, we show that relationships between the skin microbiota of a resident, his/her cohabitants, and those of non-cohabitants over time are highly personal and are possibly governed by living conditions and nature of interactions between cohabitants within households over 1 year. This study calls for increased awareness to personal and lifestyle factors that may govern relationships between the skin microbiota of one individual and those of cohabitants, and changes in the microbial association network structures within a person over time. The current study will act as a baseline for future assessments in comparing against temporal dynamics of microbiota from individuals with different skin conditions and for identifying residential factors that are beneficial in promoting the dynamics of the skin microbiota associated with health.