Bacteria in Oligotrophic Environments


Book Description

Providing over 2000 references, this is the first book to examine the ecological and physiological consequences of oligotrophy (a lack of energy to support microbial growth) on microbes in their environment. Most environments on earth are oligotrophic.




Starvation in Bacteria


Book Description

Concerted efforts to study starvation and survival of nondifferentiating vegeta tive heterotrophic bacteria have been made with various degrees of intensity, in different bacteria and contexts, over more than the last 30 years. As with bacterial growth in natural ecosystem conditions, these research efforts have been intermittent, with rather long periods of limited or no production in between. While several important and well-received reviews and proceedings on the topic of this monograph have been published during the last three to four decades, the last few years have seen a marked increase in reviews on starvation survival in non-spore-forming bacteria. This increase reflects a realization that the biology of bacteria in natural conditions is generally not that of logarithmic growth and that we have very limited information on the physiology of the energy-and nutrient-limited phases of the life cyde of the bacterial cello The growing interest in nongrowing bacteria also sterns from the more recent advances on the molecular basis of the starvation-induced nongrowing bacterial cello The identification of starvation-specific gene and protein re sponders in Escherichia coli as weIl as other bacterial species has provided molecular handles for our attempts to decipher the "differentiation-like" responses and programs that nondifferentiating bacteria exhibit on nutrient limited growth arrest. Severallaboratories have contributed greatly to the progress made in life after-log research.







Laboratory and Field Evidence for Long-Term Starvation Survival of Microorganisms in Subsurface Terrestrial Environments


Book Description

BIOGEOCHEMICAL MODELING OF GROUNDWATER FLOW AND NUTRIENT FLUX IN SUBSURFACE ENVIRONMENTS INDICATES THAT INHABITANT MICROORGANISMS EXPERIENCE SEVERE NUTRIENT LIMITATION. USING LABORATORY AND FIELD METHODS, WE HAVE BEEN TESTING STARVATION SURVIVAL IN SUBSURFACE MICROORGANISMS. IN MICROCOSM EXPERIMENTS, WE HAVE SHOWN THAT STRAINS OF TWO COMMONLY ISOLATED SUBSURFACE GENERA, ARTHROBACTER AND PSEUDOMONAS, ARE ABLE TO MAINTAIN VIABILITY IN LOW-NUTRIENT, NATURAL SUBSURFACE SEDIMENTS FOR OVER ONE YEAR. THESE NON-SPORE-FORMING BACTERIA UNDERGO RAPID INITIAL MINIATURIZATION FOLLOWED BY A STABILIZATION OF CELL SIZE. MEMBRANE LIPID PHOSPHOLIPID FATTY ACID (PLFA) PROFILES OF THE PSEUDOMONAS ARE CONSISTENT WITH ADAPTATION TO NUTRIENT STRESS; ARTHROBACTER APPARENTLY RESPONDS TO NUTRIENT DEPRIVATION WITHOUT ALTERING MEMBRANE PLFA. TO TEST SURVIVABILITY OF MICROORGANISMS OVER A GEOLOGIC TIME SCALE, WE CHARACTERIZED MICROBIAL COMMUNITIES IN A SEQUENCE OF UNSATURATED SEDIMENTS RANGING IN AGE FROM MODEM TO




Role of Starvation Genes in the Survival of Deep Subsurface Bacterial Communities. Final Report


Book Description

The investigation dealt with several aspects of subsurface bacterial survival and their nature. Mutants of Pseudomonas putida, a common environmental bacterium with counterparts in the subsurface, were isolated by transposon mutagenesis. These mutants were highly sensitive to starvation stress. Reporter gene fusions also showed that these genes were starvation genes since they were induced several fold when the cultures were started. Since the regulatory religions (promoters) of starvation genes are of interest in bioremediation and in experiments designed to understand the roles of starvation genes in the maintenance of microbial community structure, the promoter of one of these genes (pstarv1, contained in strain MK107) was characterized in detail. As a preliminary to these studies, the growth characteristics of Pseudomonas putida MK1 and MK107 were compared for cells growing in batch cultures or as an attached monolayer in microstat cultures.




Water Potential and Starvation Stress in Deep Subsurface Microorganisms


Book Description

Nine intact core samples, collected aseptically from depths of 10--436 m near the Savannah River Plant in South Carolina, were tested for water potential, microbial numbers, and microbial activity. Although all samples were collected from below the water table, two samples (a Pee Dee clay from 238 m and a Middendorf clay from 324 m) showed unsaturated conditions ( -2.7 and -2.1 MPa, respectively). Both of these samples had very low numbers of culturable cells, low microbial biomass (ATP assay), and low microbial activities (measured as respiration), suggesting that low metric waterpotentials in these strata are limiting factors to microorganisms. An Acinetobacter sp. isolated from the 324 m depth was found to maintain viability under starvation conditions in sterilized aquifer material, even when subjected to severe desiccation ( -22 MPa). A Pseudomonas sp., with the ability to oxidize thiosulfate to sulfate, was isolated from the 378 m Middendorf clay sample. This organism survived nutrient deprivation reasonably well; however, the presence of thiosulfate appeared to interfere with its normal ability to maintain viability by endogenous metabolism. Cells cultured in the presence of thiosulfate did not undergo dwarfing and cell viability declines. These are two examples of indigenous subsurface microorganisms, each with different adaptations for long-term survival under conditions of desiccation and/or starvation.




Microbiology of the Terrestrial Deep Subsurface


Book Description

Obtaining and analyzing samples is challenging in subsurface science. This first-of-its-kind reference book addresses accomplishments in this field-from drilling to sample work-up. A collaborative approach is taken, involving the efforts of microbiologists, geochemists, hydrologists, and drilling and mining experts to present a comprehensive view of subsurface research. The text provides practical information about obtaining, analyzing, and evaluating subsurface materials; the current status of subsurface microbial ecology; and describes several applications that will interest a variety of readers, including engineers, physical, and life scientists.







Stress Responses of Subsurface Bacteria. Final Report, June 1, 1995--February 1, 1998


Book Description

Five questions were investigated in this research: (1) can subsurface bacteria and phylogenetically related surface strains be cultured on a single carbon/energy substrate; (2) is the behavior of subsurface bacteria the same as phylogenetically related surface strains when both are subjected to progressive, chronic carbon/energy source starvation; (3) which phyllogenetic groups survive better; (4) do other factors affect survival in the degree that phyllogeny does (5) do dormant forms appear during starvation; (6) is ppGpp present in subsurface bacteria and what is its persistence in carbon/energy starvation?