Pyrogenic ecosystems are maintained by fires which vary in frequency, seasonality, and intensity. Florida oak-saw palmetto scrub ecosystem is characterized by fires occurring at intervals of 10-20 years. Diverse factors as private land acquisition and development has created a patchy distribution of scrub ecosystems and also interrupted the natural fire cycle. The effects of fire over plant regeneration and fauna habitat utilization of the scrub have been well characterized in previous research. In the present paper the objective is to characterize the short- and long-term fire effects on the soil microbial community. Fire effects were studied in a chronosequence, comprising a recently burned scrub during a winter-prescribed fire to scrub where fire did not occur for 40 years. The number of culturable cells was reduced by two orders of magnitude by indirect fire effects and environmental factors, principally hydric stress. However, the duration of fire effects was very short since the microbial community returned to pre-fire numbers and activity by day 47 after fire. Microbial community activity was distinctively related to inoculum density in the soil and litter samples. Soil and litter microbial communities showed differences in metabolic activity. There was no difference in substrate utilization pattern, but there was significant seasonal variation related to the decrease in water content during the month of May. Substrate utilization by litter microbial communities was higher during the month of January compared to soil microbial communities and this relationship was inversed during the month of May probably associated to the more stringent conditions, low water availability, on the litter layer. Seasonal effects outweighed fire effects in this study as this environmental constraint determined the microbial community structure and activity.

A biofilter removes biodegradable contaminants from air by passing it through a biologically-active packed bed. The microorganism community is of fundamental interest but has been the focus of few studies. This work is an investigation of the bacterial community based on the potential functional diversity of the community. <br /><br /> A number of experiments were performed in laboratory-scale biofilters using ethanol as a model contaminant. All biofilters were able to remove the ethanol with elimination capacities in the range 80 to 200gVOCm^-3h^-1; these values are comparable with published literature. Natural organic media (peat or compost) was used as packing. <br /><br /> The potential functional diversity of the community was assessed by Community-Level Physiological Profiling (CLPP) using sole-Carbon Source Utilisation Profile (CSUP). Community samples were used to inoculate Biolog EcoPlates^TM: microplates containing a selection of 31 different carbon-substrates and an indicator dye responding to bacterial growth. This technique was found to be sensitive to changes in the community structure over time and location. <br /><br /> Results showed that the community in samples taken close together (over a scale of a few centimetres) are similar and that relatively small media samples (0. 5 to 1 g) provide reproducible information. A study of a single biofilter indicated stratification of the community occurring with the community near the inlet diverging from that near the middle and outlet of the unit; this is attributed to the ethanol being degraded in the upper part of the column and the lower part of the column not being subjected to ethanol loading. In a study of two units at a higher loading rate, stratification was not observed over a period of weeks; it is suggested that the stratification may develop over this timescale as a result of the presence or absence of the Volatile Organic Compound (VOC) and not due to differences in concentration. <br /><br /> An acclimation period of 7 to 10 days was observed before near-complete removal of ethanol was attained. Monitoring of the community suggested a subsequent shift in diversity. It is suggested that the initial acclimation period is due to biofilm formation and the subsequent shift in community diversity is due to re-organisation of the community as species specialise. In a portion of the biofilter with minimal ethanol exposure, a sudden shift in community is observed after a period of some weeks. This may reflect changes as a result of starvation and indicates that periods of shut-down (when the biofilter is not loaded) may affect the community. <br /><br /> Two studies of biofilters operating in parallel were carried out. The first provided evidence of a divergence in the communities over a period of two weeks. In the second, communities in the two units underwent changes over time but observations from both units at any one time were similar. This demonstrates that biofilters set-up and operated in a similar manner may maintain similar communities but that this is not necessarily the case. This has implications for the reproducibility of laboratory experiments and for the variation of community structure with horizontal position in industrial units.

A biofilter removes biodegradable contaminants from air by passing it through a biologically-active packed bed. The microorganism community is of fundamental interest but has been the focus of few studies. This work is an investigation of the bacterial community based on the potential functional diversity of the community. <br /><br /> A number of experiments were performed in laboratory-scale biofilters using ethanol as a model contaminant. All biofilters were able to remove the ethanol with elimination capacities in the range 80 to 200gVOCm^-3h^-1; these values are comparable with published literature. Natural organic media (peat or compost) was used as packing. <br /><br /> The potential functional diversity of the community was assessed by Community-Level Physiological Profiling (CLPP) using sole-Carbon Source Utilisation Profile (CSUP). Community samples were used to inoculate Biolog EcoPlates^TM: microplates containing a selection of 31 different carbon-substrates and an indicator dye responding to bacterial growth. This technique was found to be sensitive to changes in the community structure over time and location. <br /><br /> Results showed that the community in samples taken close together (over a scale of a few centimetres) are similar and that relatively small media samples (0. 5 to 1 g) provide reproducible information. A study of a single biofilter indicated stratification of the community occurring with the community near the inlet diverging from that near the middle and outlet of the unit; this is attributed to the ethanol being degraded in the upper part of the column and the lower part of the column not being subjected to ethanol loading. In a study of two units at a higher loading rate, stratification was not observed over a period of weeks; it is suggested that the stratification may develop over this timescale as a result of the presence or absence of the Volatile Organic Compound (VOC) and not due to differences in concentration. <br /><br /> An acclimation period of 7 to 10 days was observed before near-complete removal of ethanol was attained. Monitoring of the community suggested a subsequent shift in diversity. It is suggested that the initial acclimation period is due to biofilm formation and the subsequent shift in community diversity is due to re-organisation of the community as species specialise. In a portion of the biofilter with minimal ethanol exposure, a sudden shift in community is observed after a period of some weeks. This may reflect changes as a result of starvation and indicates that periods of shut-down (when the biofilter is not loaded) may affect the community. <br /><br /> Two studies of biofilters operating in parallel were carried out. The first provided evidence of a divergence in the communities over a period of two weeks. In the second, communities in the two units underwent changes over time but observations from both units at any one time were similar. This demonstrates that biofilters set-up and operated in a similar manner may maintain similar communities but that this is not necessarily the case. This has implications for the reproducibility of laboratory experiments and for the variation of community structure with horizontal position in industrial units.

The chemical and physical processes controlling contaminant fate and transport in the vadose zone limit the options for application of many remedial technologies. Foam delivery technology (FDT) has been developed as a potential solution to overcome these limitations for remediating subsurface and deep vadose zone environments using reactive amendments. Although there are many advantages to utilizing FDT for treatment in the deep vadose zone, little information is available on how the addition of these surfactants and remedial amendments affect the indigenous microbial communities in the deep vadose zone as well as the impact of biological transformations of surfactant-based foams on remediation efforts. The purpose of this study was to develop a rapid method for assessment of microbial communities in contaminated subsurface environments. This research was divided into two phases: (1) assess the toxicity of proposed FDT components on a single bacterial species, Shewanella oneidensis MR-1; and (2) determine the effects of these components on a microbial community from the vadose zone. In Phase I, S. oneidensis MR-1 was exposed to proposed FDT components to assess potential growth inhibition or stimulation caused by these chemicals. S. oneidensis MR-1 cultures were exposed to the surfactants sodium laureth sulfate (SLES), sodium dodecyl sulfate (SDS), cocamidopropyl betaine (CAPB), and NINOL 40-CO, and the remedial amendment, calcium polysulfide (CPS). Results from this phase revealed that the relative acute toxicity order for these compounds was SDS>>CPS>>NINOL40-CO>SLES≥CAPB. High concentrations of SDS were toxic to the growth of S. oneidensis MR-1 but low concentrations were stimulatory. This benchtop system provided a capability to assess adverse microbial-remediation responses and contributed to the development of in situ remedial chemistries before they are deployed in the field. For Phase II, sediments from the BC Cribs and Trenches (BCCT) area of the Hanford Site, WA, were characterized before and after exposure to potential FDT components. First, the phylogenetic and metabolic diversity of sediment from the BCCT was assessed by sequencing the microbial community and measuring the metabolic activity. The sediment was also incubated with various concentrations of SDS, CAPB, and CPS. Phylogenetic analysis detected phylotypes from the Alpha-, Beta-, Delta-, and Gammaproteobacteria, and Actinobacteria. Unlike the S. oneidensis MR-1 studies conducted in Phase I, the surfactants and CPS stimulated the metabolic activity of the native microbial communities. The observed stimulation could be caused by sorption of the chemicals to the sediment particles, or utilization of the surfactants by the microbial communities. These findings emphasize the importance of monitoring microbial activity at remediation sites in order to determine short and long term efficacy of the treatment, compliance with regulatory mandates, and act as an early warning indicator of unintended changes to the subsurface.

The objective of this work was to understand microbial population density and diversity, both spatially and temporally, in wetland mesocosms to gain a better fundamental understanding for use in the optimization and design of constructed wetlands (CWs). A standardized community level physiological profiling (CLPP) data analysis protocol was adapted and utilized for CW mesocosms. A new one-dimensional metric was developed to track community divergence using BIOLOGTM ECO plate data. The method proved easy to use, did not require a background in multivariate statistics, and accurately described community divergence in mesocosm systems. To study mesocosm biofilm-bound bacterial communities an appropriate detachment protocol was required. Various shaking protocols were evaluated for their effectiveness in the detachment of bacteria from mesocosm pea gravel, with a focus on detachment of viable and representative bacterial communities. A protocol based on mechanical shaking with buffer and enzymes was identified as an optimal approach and used further in this study. The bacterial communities associated with the interstitial water, pea gravel media, and rhizospheric regions from both planted and unplanted CW mesocosms were profiled using the CLPP method and compared. Vertical community stratification was observed for all mesocosm systems. Rhizospheric communities were found to be significantly more active than their gravel-associated counterparts, suggesting that although rhizospheric bacteria were less abundant in the mesocosms they may play a more significant role in the removal and fate of water born contaminants. The start-up dynamics of CW mesocosms was investigated using the CLPP and standard CW characterization methods over an eight month period. All mesocosms showed a steep increase in interstitial community divergence until day 75-100, at which point a steady-state was reached. The interstitial communities were also characterized in terms of similarity based on experimental design treatments (planted/unplanted and origin of seeding inoculum). Four stages were identified during the start-up consisting of an initial stage where mesocosm communities were differentiated based on origin of the inoculum, a period where adjustments and shifts occurred in all mesocosm, a time where all mesocosm communities were quite similar, and a final state where community differentiations were made based plant presence in the mesocosms.

The objective of this work was to understand microbial population density and diversity, both spatially and temporally, in wetland mesocosms to gain a better fundamental understanding for use in the optimization and design of constructed wetlands (CWs). A standardized community level physiological profiling (CLPP) data analysis protocol was adapted and utilized for CW mesocosms. A new one-dimensional metric was developed to track community divergence using BIOLOGTM ECO plate data. The method proved easy to use, did not require a background in multivariate statistics, and accurately described community divergence in mesocosm systems. To study mesocosm biofilm-bound bacterial communities an appropriate detachment protocol was required. Various shaking protocols were evaluated for their effectiveness in the detachment of bacteria from mesocosm pea gravel, with a focus on detachment of viable and representative bacterial communities. A protocol based on mechanical shaking with buffer and enzymes was identified as an optimal approach and used further in this study. The bacterial communities associated with the interstitial water, pea gravel media, and rhizospheric regions from both planted and unplanted CW mesocosms were profiled using the CLPP method and compared. Vertical community stratification was observed for all mesocosm systems. Rhizospheric communities were found to be significantly more active than their gravel-associated counterparts, suggesting that although rhizospheric bacteria were less abundant in the mesocosms they may play a more significant role in the removal and fate of water born contaminants. The start-up dynamics of CW mesocosms was investigated using the CLPP and standard CW characterization methods over an eight month period. All mesocosms showed a steep increase in interstitial community divergence until day 75-100, at which point a steady-state was reached. The interstitial communities were also characterized in terms of similarity based on experimental design treatments (planted/unplanted and origin of seeding inoculum). Four stages were identified during the start-up consisting of an initial stage where mesocosm communities were differentiated based on origin of the inoculum, a period where adjustments and shifts occurred in all mesocosm, a time where all mesocosm communities were quite similar, and a final state where community differentiations were made based plant presence in the mesocosms.