Biology subjects

Berman, H. L.

Publications and source records attributed to Berman, H. L..

3 recordsLinked to original sources

bioRxiv2025

Does Fermentation Enhance Beverage Safety? Kombucha's Resistance to Microbial Invasion Suggests a Protective Role

Does fermentation enhance the safety of beverages? This study investigates kombuchas resilience to microbial invasion from human hands. Kombucha, an ancient fermented tea, relies on a biofilm known as a symbiotic community of bacteria and yeast (SCOBY) and a starter culture to ferment sweet tea, producing various metabolites including gluconic acid, acetic acid, ethanol, and carbon dioxide. While fermented foods have been historically associated with potential health benefits, direct evidence comparing the prevalence of human pathogens in fermented versus non-fermented beverages has been lacking. To address this, we conducted a citizen science experiment at Arizona State University, introducing swabs from peoples palms into both kombucha and a sweet tea control. Over 30 days, we monitored the bacterial and fungal composition using 16S and ITS rRNA sequencing. Our findings reveal that kombucha maintained a relatively stable microbial profile and physical appearance, with a typical SCOBY biofilm developing. In stark contrast, the sweet tea experienced a dramatic change in microbial composition and was visibly compromised by rapidly growing microorganisms. Importantly, this suggests that the complex microbial ecosystem of kombucha can limit the growth of foreign microbes introduced from human hands. Given that human pathogens were absent from the kombucha while present in the tea samples, our results indicate that the antimicrobial properties of fermentation byproducts and the physical barrier of the SCOBY may contribute to this resilience. Further research is warranted to fully elucidate the mechanisms underlying kombuchas resistance to microbial invasion.

microbiology↗

bioRxiv2025

PP2A METHYLESTERASE, PME-1, AND PP2A METHYLTRANSFERASE, LCMT-1, CONTROL SENSITIVITY TO IMPAIRMENTS CAUSED BY INJURY-RELATED OLIGOMERIC TAU

Oligomeric species of tau are a hallmark of multiple neurodegenerative diseases such as Alzheimers disease (AD) and chronic traumatic encephalopathy (CTE). Given the evidence implicating protein phosphatase 2A (PP2A) in the molecular pathogenesis of tau-related neurodegenerative disorders, we sought to determine whether manipulating the expression of enzymes that regulate PP2A activity, such as leucine carboxyl methyltransferase 1 (LCMT-1) and protein methyl esterase 1 (PME-1), might impact pathological responses to oligomeric tau. Here, we tested the effect of transgenic overexpression of LCMT-1 or PME-1 on cognitive and electrophysiological impairments caused by exposure to either recombinant oligomeric human tau or oligomeric tau prepared from mice subjected to blast-induced traumatic brain injury. We found that overexpression of LCMT-1 reduced sensitivity to tau-induced impairments, while overexpression of PME-1 increased sensitivity to these impairments. Moreover, we found that shockwave exposure increased the propensity of endogenous tau to form toxic oligomers. These results suggest that manipulating LCMT-1 or PME-1 activity may represent novel therapeutic approaches for disorders involving exposure to pathogenic forms of oligomeric tau.

neuroscience↗

bioRxiv2023

Gardnerella Diversity and Ecology in Pregnancy and Preterm Birth

The vaginal microbiome has been linked to numerous negative health outcomes including preterm birth. Specific taxa, including Gardnerella spp., have been identified as risk factors for these conditions. Historically, microbiome analysis methods have treated all Gardnerella spp. as one species, but the broad diversity of Gardnerella has recently become more apparent. In the present study, we explore the diversity of Gardnerella clades and genomic species in the vaginal microbiome of pregnant women and their impacts on microbiome composition and associations with preterm birth. Shotgun metagenomic sequencing data collected longitudinally from three distinct cohorts of pregnant women were assessed. Relative abundance of Gardnerella clades and genomic species and other taxa was quantified, and associations between Gardnerella clades and signatures of the vaginal microbiome were measured. We also assessed the diversity and abundance of Gardnerella variants in 16S rRNA gene amplicon sequencing data from seven previously conducted studies in differing populations on the vaginal microbiome and preterm birth. Individual microbiomes often contained multiple Gardnerella variants, and the number of clades was associated with increased microbial load. The genus Gardnerella was also associated with increased microbial load, or the ratio of non-human reads to human reads. Taxon co-occurrence patterns matched previously described community structures, and were largely consistent across Gardnerella clades and among cohorts. Some variants previously described as rare were prevalent in other cohorts, highlighting the importance of surveying a diverse set of populations to fully capture the diversity of Gardnerella. The diversity of Gardnerella both across populations and within individual vaginal microbiomes has long been unappreciated, as has been the intra-species diversity of many other members of the vaginal microbiome.1 The broad genomic diversity of Gardnerella has led to its reclassification as multiple species; here we demonstrate the diversity of Gardnerella found within and between vaginal microbiomes. Further studies should investigate the phenotypes of Gardnerella variants that may underlie the mechanisms by which Gardnerella species may differentially shape the vaginal microbiome.

microbiology↗