Groundbreaking research over the last 10 years has given rise to the hologenome concept of evolution. This concept posits that the holobiont (host plus all of its associated microorganisms) and its hologenome (sum of the genetic information of the host and its symbiotic microorganisms), acting in concert, function as a unique biological entity and therefore as a level of selection in evolution. All animals and plants harbor abundant and diverse microbiota, including viruses. Often the amount of symbiotic microorganisms and their combined genetic information far exceed that of their host. The microbiota with its microbiome, together with the host genome, can be transmitted from one generation to the next and thus propagate the unique properties of the holobiont. The microbial symbionts and the host interact in a cooperative way that affects the health of the holobiont within its environment. Beneficial microbiota protects against pathogens, provides essential nutrients, catabolizes complex polysaccharides, renders harmful chemicals inert, and contributes to the performance of the immune system. In humans and animals, the microbiota also plays a role in behavior. The sum of these cooperative interactions characterizes the holobiont as a unique biological entity. Genetic variation in the hologenome can be brought about by changes in either the host genome or the microbial population genomes (microbiome). Evolution by cooperation can occur by amplifying existing microbes, gaining novel microbiota and by acquiring microbial and viral genes. Under environmental stress, the microbiome can change more rapidly and in response to more processes than the host organism alone and thus influences the evolution of the holobiont. Prebiotics, probiotics, synbiotics and phage therapy are discussed as applied aspects of the hologenome concept.

Deep within the earth's crust there exists a second biosphere, composed of very primitive heat-loving bacteria and containing perhaps more living matter than is present on the earth's entire surface. That is the astounding premise of this new book by Thomas Gold, one of the twentieth century's most distinguished scientists and a man with a long history of proposing seemingly preposterous theories that later prove correct. Gold joins the deep hot biosphere argument to another, perhaps even more controversial theory for which he has marshalled evidence: that so-called fossil fuels originate not from compressed biological matter at all but from deep within the earth, present there since the planet's formation, long before our oxygen-rich surface biosphere came into existence.

In 1898, an Austrian microbiologist Heinrich Winterberg made a curious observation: the number of microbial cells in his samples did not match the number of colonies formed on nutrient media (Winterberg 1898). About a decade later, J. Amann qu- tified this mismatch, which turned out to be surprisingly large, with non-growing cells outnumbering the cultivable ones almost 150 times (Amann 1911). These papers signify some of the earliest steps towards the discovery of an important phenomenon known today as the Great Plate Count Anomaly (Staley and Konopka 1985). Note how early in the history of microbiology these steps were taken. Detecting the Anomaly almost certainly required the Plate. If so, then the period from 1881 to 1887, the years when Robert Koch and Petri introduced their key inventions (Koch 1881; Petri 1887), sets the earliest boundary for the discovery, which is remarkably close to the 1898 observations by H. Winterberg. Celebrating its 111th anniversary, the Great Plate Count Anomaly today is arguably the oldest unresolved microbiological phenomenon. In the years to follow, the Anomaly was repeatedly confirmed by all microb- logists who cared to compare the cell count in the inoculum to the colony count in the Petri dish (cf., Cholodny 1929; Butkevich 1932; Butkevich and Butkevich 1936). By mid-century, the remarkable difference between the two counts became a universally recognized phenomenon, acknowledged by several classics of the time (Waksman and Hotchkiss 1937; ZoBell 1946; Jannasch and Jones 1959).

This volume contains material first presented at an international workshop on the 'Use of Microorganisms to Combat Pollution', held in Israel, May 10--18, 1992. The workshop was sponsored by the Bat-Sheva de Rothschild Foundation for the Advancement of Science and included microbiologists, biochemists and geneticists from universities, environmental agencies and the military. Each of the contributors to this volume is an ack nowledged expert on the treatment of one or more types of pollution using microorganisms or their enzymes. This book differs from most published symposia proceedings in the breadth of coverage of each subject. Most of the chapters are divided into three parts: (a) A general presentation of the source and toxicity of the pollutant, (b) a review of the current state-of-the-science on the biodegradation of that pollutant and (c) the authors' unique research experiences on the problem. In several examples, the authors have presented data from both laboratory studies and field trials. Thus, the book contains not only the theoretical background on the biodegradation of pollutants, but also practical experiences in applying this knowledge to solving significant pollution problems.