Global diversity of enterococci and description of 18 novel species

Bacteria of the genus Enterococcus colonize the guts of diverse animals. Some species have acquired multiple antibiotic resistances on top of a high level of intrinsic resistance and have emerged as leading causes of hospital-associated infection. Although clinical isolates of enterococcal species E. faecalis and E. faecium have been studied with respect to their antibiotic resistances and infection pathogenesis, comparatively little is known about the biology of enterococci in their natural context of the guts of humans and other land animals, including arthropods and other invertebrates. Importantly, little is also known about the global pool of genes already optimized for expression in an enterococcal background with the potential to be readily acquired by hospital adapted strains of E. faecalis and E. faecium , known facile exchangers of mobile genetic elements. We therefore undertook a global study designed to reach into maximally diverse habitats, to establish a first approximation of the genetic diversity of enterococci on Earth. Presumptive enterococci from over 900 diverse specimens were initially screened by PCR using a specific reporter gene that we found to accurately reflect genomic diversity. The genomes of isolates exceeding an operationally set threshold for diversity were then sequenced in their entirety and analyzed. This provided us with data on the global occurrence of many known enterococcal species and their association with various hosts and ecologies and identified 18 novel species expanding the diversity of the genus Enterococcus by over 25%. The 18 novel enterococcal species harbor a diverse array of genes associated with toxins, detoxification, and resource acquisition that highlight the capacity of the enterococci to acquire and adapt novel functions from diverse gut environments. In addition to the discovery and characterization of new species, this expanded diversity permitted a higher resolution analysis of the phylogenetic structure of the Enterococcus genus, including identification of distinguishing features of its 4 deeply rooted clades and genes associated with range expansion such as B-vitamin biosynthesis and flagellar motility. Collectively, this work provides an unprecedentedly broad and deep view of the genus Enterococcus , along with new insights into their potential threat to human health

Global diversity of enterococci and description of 18 previously unknown species

Enterococci are gut microbes of most land animals. Likely appearing first in the guts of arthropods as they moved onto land, they diversified over hundreds of millions of years adapting to evolving hosts and host diets. Over 60 enterococcal species are now known. Two species, Enterococcus faecalis and Enterococcus faecium, are common constituents of the human microbiome. They are also now leading causes of multidrug-resistant hospital-associated infection. The basis for host association of enterococcal species is unknown. To begin identifying traits that drive host association, we collected 886 enterococcal strains from widely diverse hosts, ecologies, and geographies. This identified 18 previously undescribed species expanding genus diversity by >25%. These species harbor diverse genes including toxins and systems for detoxification and resource acquisition. Enterococcus faecalis and E. faecium were isolated from diverse hosts highlighting their generalist properties. Most other species showed a more restricted distribution indicative of specialized host association. The expanded species diversity permitted the Enterococcus genus phylogeny to be viewed with unprecedented resolution, allowing features to be identified that distinguish its four deeply rooted clades, and the entry of genes associated with range expansion such as B-vitamin biosynthesis and flagellar motility to be mapped to the phylogeny. This work provides an unprecedentedly broad and deep view of the genus Enterococcus, including insights into its evolution, potential new threats to human health, and where substantial additional enterococcal diversity is likely to be found

Düşük işlem yüküne sahip hareket kestirimi için tümlev imge temelli ikilileştirme

Günümüzde yüksek çözünürlüklü televizyonlar, kameralar, akıllı telefonların kullanımı ile birlikte yüksek çözünürlüklü video uygulamalarına talep duyulmaktadır. Bu cihazlardaki güç tüketimi ve sınırlı hafıza gibi kısıtlardan dolayı da düşük işlem yüküne sahip video kodlama yöntemlerine ihtiyaç artmaktadır. Video kodlama standartlarında halen en fazla işlem yükü hareket kestirimi kısmındadır. Bu çalışmada düşük işlem yüküne sahip, düşük bit derinliği gösterimi temelli bir hareket kestirimi yöntemi önerilmektedir. Bu yaklaşımda video çerçeveleri tümlev imge kullanılarak etkin bir şekilde ikilileştirilmekte ve video çerçevelerinin iki bit ile gösterimi elde edilmektedir. Elde edilen ikili çerçeveler üzerinden geleneksel mutlak farklar toplamı (SAD) yerine donanıma daha uygun olan dışaran veya (EX-OR) operasyonu kullanılarak uyumlama işlemi yapılmaktadır. Hareket kestiriminde ikilileştirme işlemi gerçekleştirirken tümlev imge kullanılması ilk kez bu çalışmada önerilmektedir. Önerilen yöntem, literatürde mevcut olan 1-bit dönüşüm (1BT) temelli yaklaşımlara kıyasla hareket kestirim doğruluğunu geliştirirken iki‑bit dönüşüm temelli yaklaşımların başarısı ile hemen hemen aynı seviyede olmaktadır. Bunun yanında özellikle ikilileştirme aşamasında bu yöntemlerin işlem yükünü azaltmaktadır