Within the ecosystem of open-water marine food webs, protist plankton are major contributors. While traditionally categorized into phototrophic phytoplankton and phagotrophic zooplankton, recent studies demonstrate that some organisms exhibit a blend of phototrophy and phagotrophy within a single cell, hence the term mixoplankton. Phytoplankton, particularly diatoms, are, according to the mixoplanktonic framework, incapable of phagotrophy, a condition distinct from zooplankton, which are incapable of phototrophy. This revision refashions marine food webs, upgrading their organization from regional to universal levels. We present a thorough, first-of-its-kind database of marine mixoplankton, incorporating details on organismal identification, growth patterns, biological functions, and their trophic interactions. Confronting difficulties in characterizing protist plankton life traits, researchers will find support in the Mixoplankton Database (MDB). This resource will also benefit modelers, providing a better understanding of these organisms' ecology including their intricate predator-prey interactions and allometric scaling. According to the MDB, knowledge gaps exist in understanding the nutritional needs of different mixoplankton functional types (particularly nitrate consumption, prey types, and nutritional states), along with the need to determine vital rates (like birth, death, and growth rates). The factors that impact growth, photosynthesis, and ingestion, particularly when considering the distinctions between phototrophy and phagocytosis, offer a rich field for biological investigation. Existing plankton databases now enable the revisit and reclassification of protistan phytoplankton and zooplankton, leading to a better definition of their functions within marine environments.

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 a known determinant of the formation of polymicrobial biofilms. SB505124 Yet, the foundational contribution of the coexistence of multiple bacterial species in the formation of polymicrobial biofilms remains incompletely understood. We examined how the presence of Enterococcus faecalis, Escherichia coli O157H7, and Salmonella enteritidis influenced the development of a triple-species biofilm. Our research indicated that the collective presence of these three species amplified biofilm density and facilitated a change in biofilm architecture, manifesting as a tower-like form. Moreover, the percentages of polysaccharides, proteins, and eDNAs within the extracellular matrix (ECM) composition of the triple-species biofilm exhibited substantial variations in comparison to the E. faecalis mono-species biofilm's ECM composition. Ultimately, we scrutinized the transcriptomic blueprint of *E. faecalis* in its reaction to cohabitation with *E. coli* and *S. enteritidis* within the triple-species biofilm. The results suggested *E. faecalis*'s dominance in shaping the triple-species biofilm, an effect achieved by enhancing nutrient transport, boosting the synthesis of amino acids, increasing central carbon metabolism, altering the microenvironment through biological means, and activating versatile stress response regulators. This pilot study, using a static biofilm model, demonstrates the make-up of E. faecalis-harboring triple-species biofilms, shedding new light on interspecies interactions and clinical treatment options for polymicrobial biofilms. The distinctive communal traits of bacterial biofilms impact numerous aspects of our quotidian existence. Biofilms are remarkably tolerant to chemical disinfectants, antimicrobial agents, and the host's immune defenses. Multispecies biofilms, in the natural order, are the most prominent and widespread biofilm type. Hence, there is a critical need for more research devoted to elucidating the characteristics of multispecies biofilms and the repercussions of their properties on the growth and sustainability of the biofilm community. Within a static model framework, we analyze the effects of the co-occurrence of Enterococcus faecalis, Escherichia coli, and Salmonella enteritidis on the generation of a triple-species biofilm. Transcriptomic analyses, combined with this pilot study, delve into the potential mechanisms responsible for the prevalence of E. faecalis within 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 is a matter of considerable public health concern. The frequency of infections linked to carbapenemase-producing Citrobacter spp., and notably C. freundii, is demonstrating an upward trend. In parallel with other data, a comprehensive global genomic data set describing carbapenemase-producing Citrobacter species is present. Their presence is not common. A study of 86 carbapenemase-producing Citrobacter spp. used short-read whole-genome sequencing to map their molecular epidemiology and international distribution. The results were sourced from two surveillance programs, collecting data from 2015 to 2017 inclusive. The frequency of carbapenemases, such as KPC-2 (26%), VIM-1 (17%), IMP-4 (14%), and NDM-1 (10%), was notable. From the species analysis, C. freundii and C. portucalensis were identified as the key species. Multiple clones of C. freundii were primarily isolated from Colombia (KPC-2), the United States (KPC-2 and -3), and Italy (VIM-1). From the identified *C. freundii* clones, ST98 was observed to possess blaIMP-8 from Taiwan and blaKPC-2 from the United States; ST22 displayed blaKPC-2 from Colombia and blaVIM-1 from Italy. C. portucalensis's composition was primarily defined by two clones: ST493, characterized by blaIMP-4 and restricted to Australia, and ST545, featuring blaVIM-31 and limited to Turkey. Multiple sequence types (STs) in Italy, Poland, and Portugal shared the circulation of the Class I integron (In916) containing blaVIM-1. The In73 strain, which contained the blaIMP-8 gene, circulated between various STs in Taiwan, unlike the In809 strain, carrying the blaIMP-4 gene, which circulated among different STs in Australia. Carbapenemase-producing Citrobacter spp. are a global phenomenon. Monitoring the population, which is characterized by a diversity of STs and their distinct geographical distribution, is indispensable. Precise methodologies for distinguishing Clostridium freundii and Clostridium portucalensis are necessary for a comprehensive genomic surveillance program. SB505124 Citrobacter species exhibit an importance that is profound and far-reaching. As significant contributors to hospital-acquired infections in humans, they are receiving more attention. Globally, carbapenemase-producing Citrobacter strains pose a significant threat to healthcare systems, as they are resistant to nearly all beta-lactam antibiotics. The molecular characteristics of a diverse global collection of carbapenemase-producing Citrobacter strains are presented in this study. From the carbapenemase-positive Citrobacter isolates examined in this survey, Citrobacter freundii and Citrobacter portucalensis were found to be the most abundant species. Importantly, misidentifying C. portucalensis as C. freundii using Vitek 20/MALDI-TOF MS (matrix-assisted laser desorption/ionization-time of flight mass spectrometry) has notable implications for the design of future research. Among *C. freundii*, two prominent clones emerged: ST98, distinguished by blaIMP-8 from Taiwan and blaKPC-2 from the United States; and ST22, distinguished by 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.

Cytochrome P450 enzymes demonstrate considerable promise as industrial biocatalysts, distinguished by their ability to catalyze site-selective C-H oxidation, coupled with a spectrum of catalytic reactions and a large substrate scope. An in vitro assay of conversion demonstrated the 2-hydroxylation capacity of CYP154C2, sourced from Streptomyces avermitilis MA-4680T, for androstenedione (ASD). The structure of CYP154C2 in complex with testosterone (TES) was determined at a 1.42 Å resolution, and this structure formed the basis for designing eight mutants, including single, double, and triple mutations, for improved conversion yield. SB505124 Mutants L88F/M191F and M191F/V285L displayed a considerable boost in conversion rates, specifically 89-fold and 74-fold for TES, and 465-fold and 195-fold for ASD, respectively, surpassing the wild-type (WT) enzyme while maintaining a high degree of 2-position selectivity. The L88F/M191F mutant's substrate binding affinity for TES and ASD was increased compared to the wild-type CYP154C2, a finding consistent with the experimentally observed rise in conversion efficiencies. The L88F/M191F and M191F/V285L mutants exhibited a noteworthy escalation in both total turnover and the kcat/Km ratio. Significantly, the presence of L88F in all mutants yielded 16-hydroxylation products, indicating a critical role of L88 in CYP154C2's substrate discrimination and suggesting that the analogous amino acid in the 154C subfamily impacts steroid binding orientation and substrate selectivity. The medicinal value of hydroxylated steroid derivatives is undeniable. The selective hydroxylation of methyne groups on steroid structures by cytochrome P450 enzymes can dramatically impact their polarity, biological efficacy, and toxicity. A deficiency of reports details the 2-hydroxylation of steroids; observed 2-hydroxylase P450s show a remarkably low efficiency of conversion and/or a poor degree of regio- and stereoselectivity. The current study, employing crystal structure analysis and structure-guided rational engineering strategies on CYP154C2, effectively boosted the conversion efficiency of TES and ASD, with high levels of regio- and stereoselectivity.