Effects of organic nutrients and growth factors on biostimulation of tributyltin removal by sediment microorganisms and Enterobacter cloacae

Natural attenuation can reduce contamination of tributyltin (TBT), but persistence of the xenobiotic can cause long-term issues in the environment. Biostimulation is used to accelerate biodegradation. This study investigated the ability of individual organic nutrients and growth factors to enhance TBT biodegradation by sediment microorganisms (SED) and Enterobacter cloacae strain TISTR1971 (B3). The supplements that produced high biomass yield were selected for degradation enhancement. For TBT degradation at initial concentration of 0.1 mg/l, negative or limited degradation was observed in some selected supplements indicating that increasing the biomass did not necessarily promote degradation. Consequently, the addition of nutrients was expected to increase both dioxygenase activity and the degrader population. At different concentrations of supplements, a mixture of succinate/glycerol showed the highest removal for SED which reduced TBT by 77%, 75%, and 68% for 0.1×, 1×, and 10× supplement concentration, respectively. For B3, the addition of succinate showed degradation of 49% (0.1×), 75% (1×), and 77% (10×). Most nutrients and amino acids had an inhibitory effect at 1× or 10× levels. Excess amount of the nutrients added can inhibit the initial degradation of TBT. Therefore, TBT biostimulation requires supplements that increase the capability of TBT degraders at an appropriate amount.     

Microbial transformation of steroids

A systematic study of transformation reactions of Actinomycetes with respect to the progesterone molecule was undertaken. The results obtained, i.e. the types of transformation reactions in different actinomycete species, were evaluated from the point of view of taxonomy. The actinomycetes tested were divided according to the transformation types into three groups: (1) a group of species transforming progesterone in the 16α-position; (2) a group of species transforming progesterone in the β-position; (3) a group of species in which no capacity to transform progesterone into another steroid derivative was established. From the point of view of Actinomycete classification the transformation reactions on the steroid molecule fulfil all the requirements of taxonomic features of Actinomycetes. They appear to be specific properties, independent of strictly cultivation conditions and common to all the strains of individual actinomycete species tested.     

The degradation of three-ringed polycyclic aromatic hydrocarbons by wood-inhabiting fungus Pleurotus ostreatus and soil-inhabiting fungus Agaricus bisporus

The degradation of two isomeric three-ringed polycyclic aromatic hydrocarbons by the white rot fungus Pleurotus ostreatus D1 and the litter-decomposing fungus Agaricus bisporus F-8 was studied. Despite some differences, the degradation of phenanthrene and anthracene followed the same scheme, forming quinone metabolites at the first stage. The further fate of these metabolites was determined by the composition of the ligninolytic enzyme complexes of the fungi. The quinone metabolites of phenanthrene and anthracene produced in the presence of only laccase were observed to accumulate, whereas those formed in presence of laccase and versatile peroxidase were metabolized further to form products that were further included in basal metabolism (e.g. phthalic acid). Laccase can catalyze the initial attack on the PAH molecule, which leads to the formation of quinones, and that peroxidase ensures their further oxidation, which eventually leads to PAH mineralization.A. bisporus, which produced only laccase, metabolized phenanthrene and anthracene to give the corresponding quinones as the dominant metabolites. No products of further utilization of these compounds were detected. Thus, the fungi's affiliation with different ecophysiological groups and their cultivation conditions affect the composition and dynamics of production of the ligninolytic enzyme complex and the completeness of PAH utilization.     

Sustainability governance service providers: the role of third-party product certification in facilitating corporate life cycle management

Purpose

This article aims to analyze the role that third-party product sustainability certifications play in supply chain sustainability governance and hence the impact that they may have on facilitating corporate life cycle management (LCM). Particular emphasis is given to exploring the extent to which such schemes allow firms to outsource the work of communication, motivation, enablement, and control of sustainability-related information and performance upstream in the supply chain.

Methods

The research design is based on a comparative case study methodology. The corporate practices of sourcing the sustainability certified products in the food retailing and textile sectors are compared, to explain when third-party product sustainability certification reduces the corporate need to engage in collaborative relationships with suppliers, thereby reducing efforts associated with implementation of corporate life cycle management.

Results and discussion

In our study, we found evidence that affirms the role of third-party product sustainability certification in reducing corporate necessity to actively engage with coordination of sustainability issues upstream in the supply chain. However, we also identified a range of factors—the intention of the buying company, the supply chain context, and the design of the certification scheme—that influence the extent, to which third-party product sustainability certification replaces the corporate need for additional work to facilitate supplier compliance. Some of these factors, e.g., the design of the certification scheme, are new and have been underexplored in the supply chain management and value chain governance literature yet.

Conclusions

Our findings suggest that corporate LCM practitioners should consider third-party sustainability certification as an instrument for the transfer of significant life cycle information along the supply chain and as a tool to facilitate corporate life cycle management. The extent to which third-party product sustainability certification would be able to facilitate corporate life cycle management depends not only on whether certification requirements are based on the LCA studies but also on the market scope of the certification schemes, the scope of the certification requirements, and the architecture of the certification management services. If these parameters are aligned with corporate ambitions and allow buyers to fully outsource the work associated with communication, motivation, enablement, and control of sustainability-related information and supplier performance, the life cycle management can be exercised by companies by simply choosing to procure sustainability certified products.

     

Cyanobacterial H<Subscript>2</Subscript> production — a comparative analysis

Several unicellular and filamentous, nitrogen-fixing and non-nitrogen-fixing cyanobacterial strains have been investigated on the molecular and the physiological level in order to find the most efficient organisms for photobiological hydrogen production. These strains were screened for the presence or absence of hup and hox genes, and it was shown that they have different sets of genes involved in H₂ evolution. The uptake hydrogenase was identified in all N₂-fixing cyanobacteria, and some of these strains also contained the bidirectional hydrogenase, whereas the non-nitrogen fixing strains only possessed the bidirectional enzyme. In N₂-fixing strains, hydrogen was mainly produced by the nitrogenase as a by-product during the reduction of atmospheric nitrogen to ammonia. Therefore, hydrogen production was investigated both under non-nitrogen-fixing conditions and under nitrogen limitation. It was shown that the hydrogen uptake activity is linked to the nitrogenase activity, whereas the hydrogen evolution activity of the bidirectional hydrogenase is not dependent or even related to diazotrophic growth conditions. With regard to large-scale hydrogen evolution by N₂-fixing cyanobacteria, hydrogen uptake-deficient mutants have to be used because of their inability to re-oxidize the hydrogen produced by the nitrogenase. On the other hand, fermentative H₂ production by the bidirectional hydrogenase should also be taken into account in further investigations of biological hydrogen production.Abbreviations Chl chlorophyll - MV methyl viologen     

How does forest landscape structure explain tree species richness in a Mediterranean context?

Although the strong relationship between vegetation and climatic factors is widely accepted, other landscape composition and configuration characteristics could be significantly related with vegetation diversity patterns at different scales. Variation partitioning was conducted in order to analyse to what degree forest landscape structure, compared to other spatial and environmental factors, explained forest tree species richness in 278 UTM 10 × 10 km cells in the Mediterranean region of Catalonia (NE Spain). Tree species richness variation was decomposed through linear regression into three groups of explanatory variables: forest landscape (composition and configuration), environmental (topography and climate) and spatial variables. Additionally, the forest landscape characteristics which significantly contributed to explain richness variation were identified through a multiple regression model. About 60% of tree species richness variation was explained by the whole set of variables, while their joint effects explained nearly 28%. Forest landscape variables were those with a greater pure explanatory power for tree species richness (about 15% of total variation), much larger than the pure effect of environmental or spatial variables (about 2% each). Forest canopy cover, forest area and land cover diversity were the most significant composition variables in the regression model. Landscape configuration metrics had a minor effect on forest tree species richness, with the exception of some shape complexity indices, as indicators of land use intensity and edge effects. Our results highlight the importance of considering the forest landscape structure in order to understand the distribution of vegetation diversity in strongly human-modified regions like the Mediterranean.