Applied and Environmental Microbiology最新文献

{"title":"Inactivation of deposited bioaerosols on food contact surfaces with UV-C light emitting diode devices.","authors":"Aakash Sharma, Amritpal Singh, Brahmaiah Pendyala, Sampathkumar Balamurugan, Ankit Patras","doi":"10.1128/aem.01093-24","DOIUrl":"https://doi.org/10.1128/aem.01093-24","url":null,"abstract":"<p><p>The airborne transmission of infectious diseases and bioaerosol-induced cross-contamination pose significant challenges in the food, dairy, and pharma industries. This study evaluated the effectiveness of 279 nm UV-C LED irradiation for decontaminating bioaerosols, specifically containing microorganisms such as <i>Escherichia coli</i> (C3040- Kanamycin resistant), <i>Salmonella</i> Enteritidis (ATCC 4931), and <i>Pseudomonas fragi</i> (ATCC 4973), on food contact surfaces. Borosilicate glass, silicon rubber, and stainless steel (316L) surfaces were selected for experimentation for their usage in the food industry. A 50 µL cell suspension was aerosolized at 25 psi pressure using a 4-jet BLAM Nebulizer within a customized glass chamber and then deposited onto the surface of the coupons. The serial dilution approach was used for the microbial enumeration, followed by duplicate plating. With a low Root Mean Square Error (RMSE) and high <i>R</i>² values, the biphasic kinetic model for UV-C inactivation curves of all three pathogens demonstrated the excellent goodness of fit parameters. At a UV-C dose of 6 mJ cm^-2, glass surfaces showed the maximum microbial inactivation (i.e., 2.80, 3.81, and 3.56 log CFU/mL for <i>E. coli</i>, <i>Salmonella</i>, and <i>P. fragi</i>, respectively). Stainless steel and silicon rubber surfaces showed significant microbial inactivation, but log₁₀ reductions observed were consistently lower than glass surface. Our research indicates that UV-C LEDs (279 nm) can effectively disinfect bioaerosols on food contact surfaces.IMPORTANCEFood safety is a major public health concern, with contaminated food causing serious illnesses. UV-C light, used for germicidal action, is effective in disinfecting surfaces and is not subject to the same strict legal restrictions as chemical disinfectants, simplifying compliance with food safety regulations. In this study, we evaluated the efficacy of UV-C (279 nm) LED systems for inactivation of surface-deposited bioaerosols of kanamycin-resistant <i>Escherichia coli</i> (C3040), <i>Salmonella</i> Enteritidis (ATCC 4931), and <i>Pseudomonas fragi</i> (ATCC 4973). The research outcomes can be used to develop UV-based surface disinfection systems to minimize the risk of foodborne illnesses and enhance safety in high-traffic food preparation areas.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0109324"},"PeriodicalIF":3.9,"publicationDate":"2024-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142680689","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A novel virus potentially evolved from the N4-like viruses represents a unique viral family: <i>Poorviridae</i>.","authors":"Wei Wang, Hongmin Wang, Xiao Zou, Yundan Liu, Kaiyang Zheng, Xin Chen, Xinyi Wang, Shujuan Sun, Yang Yang, Min Wang, Hongbing Shao, Yantao Liang","doi":"10.1128/aem.01559-24","DOIUrl":"https://doi.org/10.1128/aem.01559-24","url":null,"abstract":"<p><p><i>Pseudoalteromonas</i> are widely distributed in marine extreme habitats and exhibit diverse extracellular protease activity, which is essential for marine biogeochemical cycles. However, our understanding of viruses that infect <i>Pseudoalteromonas</i> remains limited. This study isolated a virus infecting <i>Pseudoalteromonas nigrifaciens</i> from Xiaogang in Qingdao, China. vB_PunP_Y3 comprises a linear, double-strand DNA genome with a length of 48,854 bp, encoding 52 putative open reading frames. Transmission electron microscopy demonstrates the short-tailed morphology of vB_PunP_Y3. Phylogenetic and genome-content-based analysis indicate that vB_PunP_Y3 represents a novel virus family named as <i>Poorviridae</i>, along with three high-quality uncultivated viral genomes. Biogeographical analyses show that <i>Poorviridae</i> is distributed across five viral ecological zones, and is predominantly detected in the Antarctic, Arctic, and bathypelagic zones. Comparative genomics analyses identified three of the seven hallmark proteins of N4-like viruses (DNA polymerase, major capsid protein, and virion-encapsulated RNA polymerase) from vB_PunP_Y3, combing with the protein tertiary structures of the major capsid protein, suggesting that vB_PunP_Y3 might evolve from the N4-like viruses.</p><p><strong>Importance: </strong>vB_PunP_Y3 is a unique strain containing three of the seven hallmark proteins of N4-like viruses, but is grouped into a novel family-level viral cluster with three uncultured viruses from metagenomics, named <i>Poorviridae</i>. This study enhanced the understanding about the genetic diversity, evolution, and distribution of <i>Pseudoalteromonas</i> viruses and provided insights into the novel evolution mechanism of marine viruses.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0155924"},"PeriodicalIF":3.9,"publicationDate":"2024-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142680688","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Variability in cadmium tolerance of closely related <i>Listeria monocytogenes</i> isolates originating from dairy processing environments.","authors":"Andrea Domen, Jenna Porter, Jared Johnson, James Molyneux, Lorraine McIntyre, Jovana Kovacevic, Joy Waite-Cusic","doi":"10.1128/aem.01281-24","DOIUrl":"https://doi.org/10.1128/aem.01281-24","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Increased tolerance to cadmium in &lt;i&gt;Listeria monocytogenes&lt;/i&gt; has been suggested to contribute to their persistence in natural and food production environments. This study investigated the phenotypic cadmium response of &lt;i&gt;L. monocytogenes&lt;/i&gt; strains with efflux pump &lt;i&gt;cadAC&lt;/i&gt; (variants 1-4) and related strains with &lt;i&gt;cadA1C1&lt;/i&gt;. Growth of &lt;i&gt;cadAC&lt;/i&gt; variant strains (&lt;i&gt;n&lt;/i&gt; = 5) in 0 µM-120 µM cadmium salts (CdCl&lt;sub&gt;2&lt;/sub&gt;, CdSO&lt;sub&gt;4&lt;/sub&gt;) in Mueller-Hinton broth (MHB) was evaluated. Additionally, 88 &lt;i&gt;L&lt;/i&gt;. &lt;i&gt;monocytogenes&lt;/i&gt; strains from dairy processing facilities were exposed to 43.8 µM CdCl&lt;sub&gt;2&lt;/sub&gt; in MHB, and their lag phase duration (LPD) was measured. Strains with &lt;i&gt;cadA1&lt;/i&gt; through &lt;i&gt;cadA3&lt;/i&gt; showed similar growth trends in the presence of cadmium, while the &lt;i&gt;cadA4&lt;/i&gt; variant (Scott A) had the highest CdCl&lt;sub&gt;2&lt;/sub&gt; minimum inhibitory concentration (175 µM). Growth varied between the two salts, with CdSO&lt;sub&gt;4&lt;/sub&gt; significantly increasing LPD (&lt;i&gt;P&lt;/i&gt; &lt; 0.05) compared to CdCl&lt;sub&gt;2&lt;/sub&gt;. In 43.8 µM CdCl&lt;sub&gt;2&lt;/sub&gt;, &lt;i&gt;cadA1&lt;/i&gt; strains displayed LPDs ranging from 0.99 ± 0.14 h to 6.44 ± 0.08 h, with no clear genomic differences explaining this variability. Strains without &lt;i&gt;cadA&lt;/i&gt; did not grow at 43.8 µM CdCl&lt;sub&gt;2&lt;/sub&gt; but exhibited low tolerance (10.9 µM CdCl&lt;sub&gt;2&lt;/sub&gt;), potentially due to non-specific soft metal ATPases (626 aa; 737 aa) and soft metal resistance proteins encoded by &lt;i&gt;czc&lt;/i&gt; genes (289 aa; 291 aa; 303 aa) within their chromosomes. These findings enhance our understanding of &lt;i&gt;L. monocytogenes&lt;/i&gt; cadmium tolerance and underscore the need for further research to explore the genetic and physiological factors underlying these trends.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Importance: &lt;/strong&gt;Mobile genetic elements in &lt;i&gt;Listeria monocytogenes&lt;/i&gt; contribute to its survival in natural and food processing environments. This study focused on how different genetic variants of the efflux pump gene &lt;i&gt;cadAC&lt;/i&gt; and group of closely related &lt;i&gt;cadA1C1&lt;/i&gt; strains respond to cadmium exposure. When exposed to two cadmium salts, cadmium chloride and cadmium sulfate, we observed varying growth patterns, with a significantly longer lag phase in cadmium sulfate compared to cadmium chloride. Strains with &lt;i&gt;cadA1&lt;/i&gt; to &lt;i&gt;cadA3&lt;/i&gt; had similar growth trends, whereas a strain with the &lt;i&gt;cadA4&lt;/i&gt; variant had the highest minimum inhibitory concentration value. Among 88 strains from dairy processing facilities, significant phenotypic differences were observed despite core genome similarities, indicating other underlying genetic and physiological factors contribute to cadmium tolerance. Since cadmium tolerance studies in &lt;i&gt;L. monocytogenes&lt;/i&gt; are limited, with rare phenotypic comparisons between closely related strains, our study makes an important observation and contribution to understanding of &lt;i&gt;L. monocytogenes&lt;/i&gt; tolerance to cadmium by providing phenotypic comparisons between numerous strains withi","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0128124"},"PeriodicalIF":3.9,"publicationDate":"2024-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142680690","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development of a suite of <i>Proteus mirabilis</i>-derived urea-inducible promoters.","authors":"Madison J Fitzgerald, Abigail Scavone, Chaitra Moolaveesala, Melanie M Pearson, Harry L T Mobley","doi":"10.1128/aem.01273-24","DOIUrl":"10.1128/aem.01273-24","url":null,"abstract":"<p><p>Catheter-associated urinary tract infections (CAUTIs) are a significant burden on healthcare systems, accounting for up to 40% of hospital-acquired infections globally. A prevalent CAUTI pathogen, <i>Proteus mirabilis,</i> is an understudied Gram-negative bacterium. One sequela of <i>P. mirabilis</i> CAUTI is the production of urinary stones, which complicates treatment and clearing of the infection. Stone formation is induced by the activity of urease, a nickel-metalloenzyme that is regulated by UreR in a urea-dependent manner. As urea is abundant in the urinary tract, urease genes are highly expressed during experimental UTI. We sought to leverage the urease promoter to create an expression system that would enable urea-inducible expression of genes during <i>in vitro</i> experiments as well as during experimental UTI. During preliminary studies, we observed unexpectedly high levels of basal expression of the urease promoter. This was somewhat dependent on the presence of regulator UreR. To further develop this expression system, we generated a series of reporter constructs to assess the impact of specific promoter elements on promoter activity in the presence and absence of urea. Elements of interest included known regulatory binding sites, alternative translational start sites, and single-nucleotide polymorphisms identified through comparative genomics. This work describes a suite of urea-inducible promoters, constructed during this study, that exhibit a variety of expression dynamics, providing a customizable platform for gene expression.IMPORTANCEUrea is an inexpensive molecule that can easily be supplied during <i>in vitro</i> experiments. A urea-inducible promoter would also be activated by environments where urea naturally occurs, such as in the urinary tract. Thus, the development of a urea-inducible system for selective gene expression is of great interest to the field of uropathogenesis as it would enable selective gene induction during experimental urinary tract infection. This expression system would also have important applications for recombinant protein production in biotech and manufacturing.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0127324"},"PeriodicalIF":3.9,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142543190","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Elevated incidence of infant botulism in a 17-county area of the Mid-Atlantic region in the United States, 2000-2019, including association with soil types.","authors":"Haydee A Dabritz, Ingrid K Friberg, Jessica R Payne, Camille Moreno-Gorrin, Kristy Lunquest, Deepam Thomas, Alexandra P Newman, Elizabeth A Negrón, Patrick J Drohan","doi":"10.1128/aem.01063-24","DOIUrl":"10.1128/aem.01063-24","url":null,"abstract":"<p><p>We sought to identify counties in the northeastern United States where the incidence of infant botulism (IB) is elevated compared to the nationwide incidence and to assess associations with soil type at the case residence. IB cases were identified through the distribution of the orphan drug Human Botulism Immune Globulin Intravenous for treatment of IB by state and national surveillance systems and were subsequently confirmed by laboratory testing. IB incidence by county was calculated as the number of IB cases divided by the number of live births in the county from 2000 to 2019. Cases were spatially mapped and assigned to soil types using the US Department of Agriculture's online soils database. Possible association with soil type was evaluated with the Chi-squared test. We identified a rectangular area consisting of 17 contiguous counties in Delaware, Maryland, New Jersey, New York, and Pennsylvania, approximately 80 km by 250 km, in which the 20-year incidence of IB was nearly seven times greater than that of the remaining counties in those five states. Within this area, case residences were strongly associated with certain soil types (<i>P</i> ≤ 0.003). From 2000 to 2019, IB occurred with disproportionate incidence in a rectangular area encompassing the lower Delaware and Raritan River Valley and parts of five adjacent states. Further investigation of the soils in counties from this area could assess whether <i>C. botulinum</i> is more prevalent in certain soil types and whether isolation of <i>C. botulinum</i> is more common in counties with higher IB incidence.</p><p><strong>Importance: </strong>Infant botulism occurs more frequently in 17 counties within and adjacent to the Delaware and Raritan River watersheds. This study should alert physicians and pediatricians in the area to the higher likelihood of encountering cases of this otherwise rare disease that manifests with constipation, poor feeding, loss of head control, weak suck/cry, generalized weakness, and descending bilateral paralysis.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0106324"},"PeriodicalIF":3.9,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142543193","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Genomic characterization of a clonal emergent <i>Salmonella</i> Minnesota lineage in Brazil reveals the presence of a novel megaplasmid of resistance and virulence.","authors":"Anamaria M P Dos Santos, Pedro Panzenhagen, Rafaela G Ferrari, Ana Beatriz Portes, Ana Carolina de Jesus, Alan Ochioni, Dália Rodrigues, Magaly Toro, Jianghong Meng, Marc Allard, Carlos A Conte-Junior","doi":"10.1128/aem.01579-24","DOIUrl":"10.1128/aem.01579-24","url":null,"abstract":"<p><p><i>Salmonella</i> Minnesota has emerged in Brazil as the predominant serovar in poultry and poultry products, along with <i>Salmonella</i> Heidelberg. To understand the emergence of <i>Salmonella</i> Minnesota over the last few years in Brazil, we performed a comparative analysis between 69 selected <i>S</i>. Minnesota genomes from Pathogen Detection database and 65 clonal emergent genomes isolated from Brazil. We demonstrate the presence of multidrug resistance genes against tetracycline [<i>tet</i>(A)], sulfonamide (<i>sul2</i>), and AmpC beta-lactamase (<i>bla</i>_CMY-2) in emergent genomes, along with the carriage of a megaplasmid of resistance and virulence (~210 kb), designated pESM (plasmid for emergent <i>Salmonella</i> Minnesota). pESM is an IncC/A2 plasmid predicted to increase <i>S</i>. Minnesota environmental tolerance to mercury (<i>mer</i> operon) and provide resistance to tetracycline and ampicillin due to the presence of <i>tet</i>(A) and <i>bla</i>_CMY-2, respectively. Moreover, pESM carries the yersiniabactin siderophore (high-pathogenicity island of <i>Yersinia</i>) related to the iron uptake. The temporal inference demonstrated that the most recent common ancestor dated from ~1978 and that the clonal emergent genomes carrying the pESM belong to a completely different lineage of <i>S</i>. Minnesota. Our results indicate that the presence of pESM likely contributes to the emergence of <i>S</i>. Minnesota and is precisely related to the successful spread of this particular clonal lineage in Brazil.IMPORTANCE<i>Salmonella</i> Minnesota has emerged in Brazil as one of the leading serovars related to human and animal infection, presenting high virulence and antibiotic resistance to drugs classified as the highest priority for clinical treatment in humans. This study performed whole-genome sequencing, temporal analysis, and phylogenetics to understand the genetic insights related to the emergence of <i>Salmonella</i> Minnesota in Brazil. Long-read sequencing has led to the identification and characterization of a unique megaplasmid carrying virulence, antibiotic resistance, and heavy-metal tolerance genes, which may play a central role in <i>S</i>. Minnesota's successful emergence in Brazil and possibly worldwide. The potentially high transmissibility of this plasmid between clones and serovars represents a risk to public health since its acquisition may increase <i>Salmonella</i>'s fitness, virulence, resistance, and persistence. Understanding the genetic aspects related to the emergence of serovars can help devise measures to mitigate the spread of hazardous multidrug-resistant strains.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0157924"},"PeriodicalIF":3.9,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142543206","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Differential expression of the <i>yfj</i> operon in a <i>Bacillus subtilis</i> biofilm.","authors":"James P Finn, Cora Luzinski, Briana M Burton","doi":"10.1128/aem.01362-24","DOIUrl":"10.1128/aem.01362-24","url":null,"abstract":"<p><p>Type VII protein secretion systems play an important role in the survival and virulence of pathogens and in the competition among some microbes. Potential polymorphic toxin substrates of the type VII secretion system (T7SS) in <i>Bacillus subtilis</i> are important for competition in the context of biofilm communities. Within a biofilm, there is significant physiological heterogeneity as cells within the population take on differential cell fates. Which cells express and deploy the various T7SS substrates is still unknown. To identify which cells express at least one of the T7SS substrates, we investigated the <i>yfj</i> operon. The <i>yfjABCDEF</i> operon encodes at least one predicted T7SS substrate. Starting with an <i>in silico</i> analysis of the <i>yfj</i> operon promoter region, we identified potential regulatory sequences. Using a <i>yfj</i> promoter-reporter fusion, we then identified several regulators that impact expression of the operon, including a regulator of biofilm formation, DegU. In a <i>degU</i> deletion mutant, <i>yfj</i> expression is completely abolished. Mutation of predicted DegU binding sites also results in a significant reduction in <i>yfj</i> reporter levels. Further analysis of <i>yfj</i> regulation reveals that deletion of <i>spo0A</i> has the opposite effect of the <i>degU</i> deletion. Following the <i>yfj</i> reporter by microscopy of cells harvested from biofilms, we find that the <i>yfj</i> operon is expressed specifically in the subset of cells undergoing sporulation. Together, our results define cells entering sporulation as the subpopulation most likely to express products of the <i>yfj</i> operon in <i>B. subtilis</i>.IMPORTANCEDifferential expression of genes in a bacterial community allows for the division of labor among cells in the community. The toxin substrates of the type VII secretions system (T7SS) are known to be active in <i>Bacillus subtilis</i> biofilm communities. This work describes the expression of one of the T7SS-associated operons, the <i>yfj</i> operon, which encodes the YFJ toxin, in the sporulating subpopulation within a biofilm. The evidence that the YFJ toxin may be deployed specifically in cells at the early stages of sporulation provides a potential role for deployment of T7SS in community-associated activities, such as cannibalism.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0136224"},"PeriodicalIF":3.9,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142456516","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"<i>Alicyclobacillus suci</i> produces more guaiacol in media and has duplicate copies of <i>vdcC</i> compared to closely related <i>Alicyclobacillus acidoterrestris</i>.","authors":"Katerina Roth, Yadwinder Singh Rana, Randy Worobo, Abigail B Snyder","doi":"10.1128/aem.00422-24","DOIUrl":"10.1128/aem.00422-24","url":null,"abstract":"<p><p>Some species of the genus <i>Alicyclobacillus</i> cause spoilage in juices and other beverages due to the production of guaiacol, a phenolic compound, and off-aroma. However, little is known about the genomic determinants of guaiacol production across the genus. In this study, we found that several of the genes significantly enriched in guaiacol-producing <i>Alicyclobacillus</i> spp. are associated with oxidative stress response, including <i>vdcC</i>, a phenolic acid decarboxylase putatively responsible for guaiacol synthesis. The food industry recognizes <i>Alicyclobacillus acidoterrestris</i> as the primary guaiacol-producing species found in beverages, though that species was recently split into two closely related yet genetically distinct species, <i>Alicyclobacillus suci</i> and <i>A. acidoterrestris</i>. We found that strains of <i>A. suci</i> (63.0 ± 14.2 ppm) produced significantly (<i>P</i> < 0.01) more guaiacol on average in media than did strains of <i>A. acidoterrestris</i> (25.2 ± 7.0 ppm). Additionally, <i>A. suci</i> and <i>Alicyclobacillus fastidiosus</i> genomes each had duplicate copies of <i>vdcC</i>, while only a single copy of <i>vdcC</i> was found in the genomes of <i>A. acidoterrestris, Alicyclobacillus acidiphilus,</i> and <i>Alicyclobacillus herbarius</i>. Although the food industry has not historically differentiated between <i>A. suci</i> and <i>A. acidoterrestris,</i> it may be increasingly important to target the species with greater spoilage potential. Therefore, we also demonstrated that sequencing a single locus, such as the full-length 16S region or <i>rpoB,</i> is sufficient to differentiate between <i>A. acidoterrestris</i> and <i>A. suci</i>.</p><p><strong>Importance: </strong>Microbial spoilage increases food waste. To address that challenge, it is critical to recognize and control those microbial groups with the greatest spoilage potential. Non-specific targeting of broad microbial groups (e.g., the genus of <i>Alicyclobacillus</i>) in which only some members cause food spoilage results in untenable, overly broad interventions. Much of the food industry does not differentiate between guaiacol-producing and non-guaiacol-producing <i>Alicyclobacillus</i> species. This is overly broad because <i>Alicyclobacillus</i> spp. which cannot produce guaiacol can be present in beverages without causing spoilage. Furthermore, no distinction is made between <i>Alicyclobacillus suci</i> and <i>Alicyclobacillus acidoterrestris</i> because <i>A. suci</i> is newly split from <i>A. acidoterrestris</i> and most of the food industry still considers them to be the same. However, these findings indicate that <i>A. suci</i> may have greater spoilage potential than <i>A. acidoterrestris</i> due to differences in their genomic determinants for guaiacol production.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0042224"},"PeriodicalIF":3.9,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142387430","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of wildfire on soil microbial communities in karst forest ecosystems of southern Guizhou Province, China.","authors":"Xu Li, Yanfeng Han, Yunlin Zhang, Qiuyu Shao, Chunbo Dong, Jianfeng Li, Bo Ding, Yanwei Zhang","doi":"10.1128/aem.01245-24","DOIUrl":"10.1128/aem.01245-24","url":null,"abstract":"<p><p>Wildfires are unpredictable disturbances with profound effects on soil properties and microbial communities within forest ecosystems. However, knowledge of post-fire microbial communities in karst forests remains limited. In this study, microbial amplicon sequencing techniques were employed to investigate the impact of wildfires on the composition, diversity, function, and co-occurrence network of soil microbial communities in karst forest landscapes and to identify the key soil physicochemical factors affecting the post-fire microbial communities. The wildfire affected the fungal community to a greater extent than the bacterial community, with the former shifting from a dominance of Basidiomycota to Ascomycota at the phylum level, while the relative abundance of Actinobacteria increased significantly in the bacterial community. Moreover, the wildfire increased the α-diversity of the microbial community and changed the β-diversity. Network analysis indicated significant reductions in the complexity of microbial community networks and the hub microbiome in burned soils compared to those of unburned soils. Functional predictions indicated an increase in the highly abundant functional taxa of chemoheterotrophic and aerobic chemoheterotrophic bacteria, along with a significant rise in saprotrophic functional fungal taxa following the fire. In addition, soil organic matter, total nitrogen, total phosphorus, and soil water content emerged as key soil physicochemical factors affecting post-fire soil microbial communities in the karst forest. Overall, this study revealed the structural and functional characteristics of soil microbial communities and their key influencing factors after a fire in a karst forest, which will provide a valuable theoretical basis for ecosystem restoration after a wildfire.IMPORTANCEDespite the significant impacts of wildfires on forest ecosystems, most existing studies have largely focused on boreal and Mediterranean coniferous forest types, with limited research on the impacts of coniferous and broadleaf forest types in subtropical karst regions. This study reveals the effects of wildfires on soil microbial communities of coniferous and broadleaf forest types in a karst forest. The results of this study not only improve the understanding of the effects of wildfires on the composition, diversity, function, and network of soil microbial communities but also provide a meaningful theoretical basis for post-fire ecosystem restoration in the karst forest.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0124524"},"PeriodicalIF":3.9,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142543192","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Identification and characterization of a novel formaldehyde dehydrogenase in <i>Bacillus subtilis</i>.","authors":"Vivien Jessica Klein, Susanne Hansen Troøyen, Luciana Fernandes Brito, Gaston Courtade, Trygve Brautaset, Marta Irla","doi":"10.1128/aem.02181-23","DOIUrl":"10.1128/aem.02181-23","url":null,"abstract":"<p><p>Formaldehyde is a known toxic compound, and functional formaldehyde detoxification is crucial for the survival of all living cells. Such detoxification systems are of particular importance for methylotrophic microorganisms that rely on formaldehyde as a central metabolite in their one-carbon metabolism. Understanding formaldehyde dissimilation pathways in non-methylotrophic industrial microorganisms is necessary for ongoing research aiming at engineering methylotrophy into their metabolism (synthetic methylotrophy). There is a variety of formaldehyde dissimilation pathways across microorganisms, often based on the activity of formaldehyde dehydrogenases. In this study, we investigated the role of the <i>yycR</i> gene of <i>Bacillus subtilis</i> putatively encoding a novel, uncharacterized zinc-type alcohol dehydrogenase-like protein. We showed that the <i>B. subtilis</i> Δ<i>yycR</i> mutant displayed a reduced formaldehyde tolerance level and confirmed the enzymatic activity of recombinantly produced and purified YycR as formaldehyde dehydrogenase <i>in vitro</i>. Biochemical analyses demonstrated that YycR activity is optimal at 40°C, with the highest measured activity at pH 9.5, formaldehyde is the preferred substrate, and the kinetic constants are <i>K_m</i> of 0.19 ± 0.05 mM and <i>V</i>_max of 2.24 ± 0.05 nmol min^-1. Altogether, we showed that YycR is a novel formaldehyde dehydrogenase with a role in formaldehyde detoxification in <i>B. subtilis</i>, providing valuable insights for future research on synthetic methylotrophy in this organism.</p><p><strong>Importance: </strong>Formaldehyde is a key metabolite in methanol assimilation for many methylotrophic microorganisms, and at the same time, it is toxic to all living cells, which means its intracellular concentrations must be tightly controlled. An in-depth understanding of methanol detoxification systems in industrially relevant microorganisms is a prerequisite for the introduction of methanol utilization pathways into their metabolism (synthetic methylotrophy). <i>Bacillus subtilis</i>, an industrial workhorse conventionally used for the production of enzymes, is known to possess two formaldehyde detoxification pathways. Here, we identify a novel formaldehyde dehydrogenase in this bacterium as a path towards creating innovative prospect strategies for strain engineering towards synthetic methylotrophy.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0218123"},"PeriodicalIF":3.9,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142520800","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}