Putative functions and co-occurrence patterns of the microbial communities in natural and engineered ecosystems

Understanding functions and co-occurrence patterns of microbial communities in various ecosystems enriches the knowledge on ecosystem characteristics and microbial ecology. However, such analyses have rarely been reported. Herein, functions and inter-taxa correlations of microbial communities in a set of natural environments (farmland (SA), forest soil (SB) and Caspian Sea sediments (CSS)) and engineered ecosystems (wastewater treatment plants (FW, WA and WB) and anaerobic digesters (AD)) were studied based on FAPROTAX and network analyses, respectively, by a collection of 115 samples from seven published 16S rRNA gene datasets generated by high-throughput sequencing. The results show that chemoheterotrophy related populations were the most abundant in almost all the communities. Their relative abundances (RAs) in the AD systems were the highest (43.7%±4.2%), followed by those of the soil environments (40.2%±1.9% in SA and 36.4%±2.0% in SB). For each ecosystem, the indicative community and overall community showed differentiations in several function categories. For example, the SA and SB indicative communities showed higher RAs in aerobic chemoheterotrophy, the CSS indicative community showed higher RAs in sulfate respiration, the AD indicative community showed higher RAs in fermentation, and the WB indicative community included higher RAs of predatory/exoparasitic bacteria. Three molecular ecological networks of the communities from the AD, WB and SB datasets were constructed, respectively. The WB network showed the highest proportion of negative correlations (70.4%), possibly attributed to the environmental pressure which aggravated microbial competition. The positively correlated taxa showed lower phylogenetic distances than the negatively correlated taxa on average in each network.

Buffy the Vampire Slayer

Buffy the Vampire Slayer is an American television series (1997–2003). Its first incarnation was as a movie (1992) that received mediocre reviews. The film’s writer, Joss Whedon, had the unexpected opportunity to transfer the work to television as part of the fledgling WB network. (Its last two seasons were on UPN.) The series soon garnered high critical praise and devoted viewers, though their numbers were only large in the context of a start-up network, where it was, however, allowed greater creative freedom. The show became culturally significant beyond its immediate fanbase. Buffy became famous for its gender politics: the main character reverses the usual horror trope of the young beauty killed by a monster. Buffy, whose slight stature belies her strength, derives from a long line of female Slayers, only one of whom exists in any generation. However, Buffy’s attractiveness comes in part from her flaws: she is constantly torn between her duties and her desire for a normal life. The California small-town setting suggests the darkness underlying suburbia: Sunnydale sits on a Hellmouth, where monsters converge. Each monstrous encounter is not only an adventure and a test of strength and ethics, but also symbolizes problems faced in reality, the “high school is hell” metaphor central to the show. Buffy is aided by a geeky but loyal boy, Xander; a shy computer whiz (and later witch), Willow; a book-smart mentor, Giles; a vampire seeking redemption, Angel (soon Buffy’s forbidden love); this group later expands to include others. A main theme is the idea of chosen family or working in community rather than fighting alone. Immediately admired for its witty dialogue (known as Buffyspeak or Slayer Slang), the show gradually explored more and more complex problems through building continuity of narrative, which reflects the classic hero’s journey but also involves many other storylines. Buffy is noteworthy for having the first long-running romance between two lesbian characters on network television; one of the two lovers is murdered, setting off a supernatural rampage by the survivor, Willow (and fan indignation). In the final episode Buffy shares her power around the world with Willow’s help. Buffy has a television spin-off, Angel (1999–2004) and continues in comic book form with Season Eight and more; some do not consider the comics canonical. Buffy spawned numerous online discussion forums. With its aesthetic and cultural value, Buffy has accrued more scholarly writing than any other television series.