As major players in open-water marine food webs, protist plankton are indispensable. The conventional distinction between phototrophic phytoplankton and phagotrophic zooplankton is challenged by recent findings that many organisms, exhibiting both phototrophy and phagotrophy within their single cells, are now identified as mixoplankton. The mixoplankton model dictates that phytoplankton, exemplified by diatoms, are unable to practice phagotrophy, whereas zooplankton are incapable of phototrophy. This revision fundamentally alters marine food webs, shifting the scope from regional to a global framework. Herein, we present the first comprehensive database of marine mixoplankton, integrating existing knowledge on their identification, scaling characteristics, physiological capacities, and their feeding relationships. The Mixoplankton Database (MDB) will aid researchers challenged in defining the characteristics of protist plankton, whilst also empowering modelers to better understand these organisms' complex ecological roles, specifically concerning their intricate predator-prey interactions and allometric influences. Mixoplankton functional types, as assessed by the MDB, present knowledge gaps in understanding their nutrition (derived from nitrate, various prey, and their nutritional condition), as well as in obtaining essential vital rates (like growth and reproduction parameters). The factors that impact growth, photosynthesis, and ingestion, particularly when considering the distinctions between phototrophy and phagocytosis, offer a rich field for biological investigation. Protistan phytoplankton and zooplankton within existing plankton databases can now be revisited and reclassified, illuminating their contributions to marine ecosystem dynamics.

Chronic infections, a consequence of polymicrobial biofilms, are frequently resistant to effective treatment due to the elevated tolerance of the biofilms to antimicrobial agents. Interspecific interactions are recognized as factors affecting the development of polymicrobial biofilms. find more However, the underlying contribution of diverse bacterial species cohabiting within polymicrobial biofilms is not yet fully elucidated. This study explored the impact of simultaneous colonization by Enterococcus faecalis, Escherichia coli O157H7, and Salmonella enteritidis on the formation of a biofilm involving all three species. Our observations indicated that the presence of all three species together bolstered biofilm volume and induced a structural modification within the biofilm, transforming it into a tower-like structure. Compared to the E. faecalis mono-species biofilm, the triple-species biofilm's extracellular matrix (ECM) showed considerable variations in the proportion of polysaccharides, proteins, and eDNAs. In the final stage of our investigation, we examined the transcriptomic changes in *E. faecalis* in response to shared living space with *E. coli* and *S. enteritidis* within a triple-species biofilm. The research findings demonstrate *E. faecalis*'s established dominance over the triple-species biofilm, characterized by its ability to optimize nutrient transport and amino acid biosynthesis, increase central carbon metabolic function, manipulate the microenvironment through biological agents, and activate diverse stress response regulators. A static biofilm model was used in this pilot study to show the essence of E. faecalis-harboring triple-species biofilms, with novel implications for understanding interspecies interactions and developing effective clinical treatments for polymicrobial biofilms. Distinct community characteristics inherent in bacterial biofilms influence a multitude of aspects impacting our daily routines. Importantly, biofilms display a significantly improved tolerance towards chemical disinfectants, antimicrobial agents, and host immune responses. In the natural environment, multispecies biofilms are, without a doubt, the most common type of biofilm. Consequently, a significant imperative exists for further investigations focused on characterizing multispecies biofilms and the impact of their properties on biofilm community development and persistence. A static model is used to assess the impact of the combined presence of Enterococcus faecalis, Escherichia coli, and Salmonella enteritidis on the establishment of a triple-species biofilm. This pilot study, in conjunction with transcriptomic analyses, examines the underlying mechanisms that contribute to E. faecalis's dominance in triple-species biofilms. Through our research on triple-species biofilms, we've gained novel understanding, showing the crucial importance of multispecies biofilm composition in choosing appropriate antimicrobial methods.

The emergence of carbapenem resistance warrants significant public health concern. Carbapenemase-producing Citrobacter spp., particularly C. freundii, are showing an increasing trend in infection rates. In conjunction, a complete global genomic database on carbapenemase-producing species of Citrobacter is readily available. There is a lack of them. To characterize the molecular epidemiology and international dissemination of 86 carbapenemase-producing Citrobacter species, short read whole-genome sequencing was utilized. These findings were collected by two surveillance programs during the period of 2015 to 2017. Of the observed carbapenemases, KPC-2 (26%), VIM-1 (17%), IMP-4 (14%), and NDM-1 (10%) were the most frequently encountered. C. freundii and C. portucalensis constituted the major proportion of the species present. Clones of C. freundii, predominantly from Colombia (carrying KPC-2), the United States (featuring KPC-2 and -3), and Italy (with VIM-1), were identified. ST98, a prevailing *C. freundii* clone, was identified as carrying the blaIMP-8 gene from Taiwan, and blaKPC-2 from the United States. In contrast, ST22, another prominent *C. freundii* clone, was found to carry blaKPC-2 from Colombia and blaVIM-1 from Italy. Two principal clones, ST493 bearing blaIMP-4 and geographically restricted to Australia, and ST545 possessing blaVIM-31, limited to Turkey, constituted the majority of C. portucalensis. The blaVIM-1-carrying Class I integron (In916) was found circulating across multiple sequence types (STs) in Italy, Poland, and Portugal. Amongst various STs in Taiwan, the In73 strain, which carried the blaIMP-8 gene, was circulating, in contrast to the In809 strain, containing the blaIMP-4 gene, circulating between disparate STs in Australia. Citrobacter species, which are carbapenemase producers, are found globally. The diverse ST populations, distinguished by varied characteristics and geographical distributions, necessitate ongoing monitoring efforts. Methods for genomic surveillance of Clostridium species should effectively discriminate between Clostridium freundii and Clostridium portucalensis. find more Citrobacter species hold significant importance. A growing understanding of their importance in causing hospital-acquired infections in humans is emerging. Carbapenemase production in Citrobacter species is a matter of great concern to global healthcare services, as these strains are resistant to virtually all beta-lactam antibiotics. This document explicates the molecular makeup of a global collection of Citrobacter species, which demonstrate carbapenemase production. The prevalence of carbapenemase-producing Citrobacter species in this survey was dominated by Citrobacter freundii and Citrobacter portucalensis. The misidentification of C. portucalensis as C. freundii using Vitek 20/MALDI-TOF MS (matrix-assisted laser desorption/ionization-time of flight mass spectrometry), a finding with implications for future research, underscores the importance of validation procedures. Two prominent clones of *C. freundii* were noted: ST98, exhibiting blaIMP-8 from Taiwan and blaKPC-2 from the USA, and ST22, displaying blaKPC-2 from Colombia and blaVIM-1 from Italy. For the C. portucalensis strain, the dominant clones comprised ST493 with its blaIMP-4 gene from Australia, and ST545 with its blaVIM-31 gene from Turkey.

Industrial applications of cytochrome P450 enzymes are promising due to their ability to catalyze site-selective C-H oxidation reactions, along with their diverse catalytic capabilities and broad substrate acceptance. The 2-hydroxylation activity of CYP154C2 from Streptomyces avermitilis MA-4680T, in the presence of androstenedione (ASD), was established via an in vitro conversion assay. The crystal structure of CYP154C2, complexed with testosterone (TES), was solved at 1.42 Å resolution, and this structure was leveraged to engineer eight mutants, including single, double, and triple mutants, with the intent of optimizing conversion efficiency. find more The wild-type (WT) enzyme's conversion rates were significantly outperformed by the L88F/M191F and M191F/V285L mutants, showing increases of 89-fold and 74-fold for TES, and 465-fold and 195-fold for ASD, respectively, while still exhibiting high 2-position selectivity. The L88F/M191F mutant demonstrated a greater attraction to TES and ASD as substrates, compared with the wild-type CYP154C2, which aligned with the amplified conversion efficiencies observed. Significantly greater total turnover values, coupled with elevated kcat/Km ratios, were observed in the L88F/M191F and M191F/V285L mutants. Fascinatingly, mutants carrying L88F consistently produced 16-hydroxylation products, indicating a vital role of L88 in CYP154C2's substrate specificity, and implying that the amino acid counterpart to L88 in the 154C subfamily impacts the configuration of steroid binding and substrate preference. Medical applications rely heavily on the essential functions of hydroxylated steroid compounds. The selective hydroxylation of methyne groups on steroid structures by cytochrome P450 enzymes can dramatically impact their polarity, biological efficacy, and toxicity. The available literature regarding the 2-hydroxylation of steroids is limited; documented 2-hydroxylase P450s demonstrate extremely low conversion rates and/or low regio- and stereoselectivity. Crystal structure analysis and structure-guided rational engineering of CYP154C2, performed in this study, successfully boosted the conversion efficiency of TES and ASD, achieving high regio- and stereoselectivity.