Changes in Prokaryote and Eukaryote Assemblages Along a Gradient of Hydrocarbon Contamination in Groundwater

Groundwater biota are particularly sensitive to environmental perturbations such as groundwater contamination. The diversity of prokaryotic and eukaryotic biota has been examined along a gradient of chlorinated hydrocarbon (CHC) contamination in the Botany Sands, an urban coastal sand-bed aquifer (Sydney, Australia). Molecular techniques were used to analyze the richness and composition of prokaryote and eukaryote assemblages using 16S and 18S rDNA, respectively. Taxon richness did not change significantly along the gradient for either prokaryotes or eukaryotes; however, significant shifts in assemblage composition were evident for both groups. Assemblage changes were most strongly correlated with concentrations of the major CHC, cis-1,2-dichloroethene, but the concentrations of a number of the contaminants were also correlated, making it difficult to infer if effects were due to any particular contaminant. The presence of cis-1,2-dichloroethene and other secondary ethenes suggests in situ breakdown of the primary CHCs via natural attenuation. The current focus of management of the Botany aquifer is to stop the contaminant plume reaching the adjoining estuary. This approach is clearly justified given the changes evident in the microbial assemblages in the groundwater, which are a likely consequence of the contamination.     

Contractual National Parks and the Makuleke Community

Contractual national parks in South Africa are established on land owned either by the state or by a group of private individuals, but managed by South African National Parks (SANP) according to the terms of a joint management agreement drawn up by a joint management committee consisting of representatives from SANP and the landowners. Since majority rule in 1994, contractual national parks have been seen as a model through which the country's conservation as well as development objectives can be met, particularly where landowners are previously disadvantaged communities. This study looks at the Makuleke region of Kruger National Park in order to ascertain how successful the contractual national park model is in meeting conservation, social, and economic objectives for the area.     

Performance evaluation and microbial community analysis of the composite filler micro-embedded with Pseudomonas putida for the biodegradation of toluene

The composite filler micro-embedded with Pseudomonas putida (P. putida) was prepared and the biodegradation performance of the filler was evaluated in a biofilter. Five phases were set up to evaluate the performance of the biofilter under different toluene inlet loadings and transient shock loadings. In particular, the microbial community structure in the biofilms and fillers was measured by sequence analysis of the 16S rRNA gene. The results show that the biofilter packed with the composite fillers was suitable for the biodegradation of toluene. The biofilter could start up quickly with high removal efficiency (RE), and remain above 90 % RE when the empty bed residence time (EBRT) was 18 s and the inlet loading rates were not higher than 41.4 g/(m³·h). Moreover, the biofilter could tolerate substantial transient shock loadings. The high removal efficiency and elimination capacity contributed to rich bacterial communities for the efficient degradation of toluene. The dominant microbial communities at the phylum level were mainly Firmicutes, Actinobacteria and Proteobacteria. It is noteworthy that the abundance of Bacteroidetes at phylum level and Chungangia and Stenotrophomonas at genus level increased significantly during the re-start period.     

Toward enhanced performance of integrated photo-bioelectrochemical systems: Taxa and functions in bacteria–algae communities

An integrated photo-bioelectrochemical (IPB) system uses microalgae in the cathode of a microbial fuel cell to achieve higher electricity generation and nutrient removal from wastewater. Using multivariate analysis and surveys of IPB studies, this paper identifies key algal and bacterial taxa and discusses their functions critical for IPB performance. Unicellular algae with high photosynthetic oxygen production and biofilm formation can enhance IPB energy production. Diverse bacterial taxa achieve nitrogen transformations and can improve total nitrogen removal. Understanding bacteria–algae interactions via quorum sensing in the IPB cathode may potentially aid in boosting system performance. Future advances in development of IPBs for wastewater treatment will benefit from interdisciplinary collaboration in analysis of microbial community functions.