Abstract: Gallic acid (GA) is a polyphenols compound commonly present in wastewater that immensely affects aquatic and human life. GA is also responsible for the inhibitory effects on the microbial activity in the soil, thereby decreasing the fertility of the soil. Therefore, the removal of GA from the wastewater is necessary to combat such issues. The present study focused on the synthesis of reduced graphene oxide (rGO) incorporated bimetallic (Cu/Bi) based nanorods (r-GO-Cu/Bi-NRs) and their photocatalytic applications. Incorporating GO within the CuBi2O4-NRs might decrease the bandgap value, thereby increasing the interfacial charge transfer. Moreover, GO increased the reactive sites and oxygen defects onto the r-GO-Cu/Bi-NRs that led to the separation rate of the photo-induced charge carriers and migration, thereby enhancing the photodegradation ability of the synthesized r-GO-Cu/Bi-NRs. The synthesis process of the r-GO-Cu/Bi-NRs is facile, novel, and economically viable for the photocatalytic degradation of organic pollutants.

Abstract: Several bacteria use the plant hormone indole-3-acetic acid (IAA) as a sole carbon and energy source. A cluster of genes (named iac) encoding IAA degradation has been reported in Pseudomonas putida 1290, but the functions of these genes are not completely understood. The plant-growth-promoting rhizobacterium Paraburkholderia phytofirmans PsJN harbors iac gene homologues in its genome, but with a different gene organization and context than those of P. putida 1290. The iac gene functions enable P. phytofirmans to use IAA as a sole carbon and energy source. Employing a heterologous expression system approach, P. phytofirmans iac genes with previously undescribed functions were associated with specific biochemical steps. In addition, two uncharacterized genes, previously unreported in P. putida and found to be related to major facilitator and tautomerase superfamilies, are involved in removal of an IAA metabolite called dioxindole-3-acetate. Similar to the case in strain 1290, IAA degradation proceeds through catechol as intermediate, which is subsequently degraded by ortho-ring cleavage. A putative two-component regulatory system and a LysR-type regulator, which apparently respond to IAA and dioxindole-3-acetate, respectively, are involved in iac gene regulation in P. phytofirmans. These results provide new insights about unknown gene functions and complex regulatory mechanisms in IAA bacterial catabolism. IMPORTANCE This study describes indole-3-acetic acid (auxin phytohormone) degradation in the well-known betaproteobacterium P. phytofirmans PsJN and comprises a complete description of genes, some of them with previously unreported functions, and the general basis of their gene regulation. This work contributes to the understanding of how beneficial bacteria interact with plants, helping them to grow and/or to resist environmental stresses, through a complex set of molecular signals, in this case through degradation of a highly relevant plant hormone.

Abstract: Laternula elliptica is a key bivalve species and widely distributed around the Antarctic continent. This bivalve has been the study subject in several studies centered on ecological, physiological, biochemical, and behavioral patterns. However, little is known about the chemistry and the biomechanical properties of the shells of this mollusk. Here, we present the first report of the intra-population variability in the organic composition and mechanical properties of L. elliptica shells. Further, we analyze different morphological traits and their association with the metabolism of a population of L. elliptica from King George Island, Western Antarctic Peninsula. The summer metabolic rates and the hepatosomatic index values indicate good health conditions of this clam's population. Shell periostracum chemistry is quite similar to bivalves from temperate regions, but the relative amount of protein increased ca. five-fold in shells of L. elliptica. The microhardness is approximately 32% lower than in bivalves from temperate regions. Our characterization of the L. elliptica shells suggests that periostracum chemistry could be specially fitted to avoid shell carbon exposure to dissolution (e.g., in corrosive acidified seawater). In contrast, the reduction in shell hardness may result from prioritizing behavioral (burial) and shell repairing strategies to confront biological (predators) and physical disturbances (e.g., ice scouring). Similar studies in other Antarctic mollusks will help understand the role of shell structure and function in confronting projected climate changes in the Antarctic ocean.

Abstract: In intertidal poikilotherms with wide geographic distribution, physiological variations are ubiquitous, due to phenotypic plasticity and/or individual geographic variation. Using the grapsid crab, Cyclograpsus cinereus as a study model, acclimatization differences in respiratory physiology were evaluated among populations along the Chilean coast, covering a latitudinal gradient of about 2000km. This species inhabits the supratidal zones and, therefore, is subject to constant immersion and emersion periods, producing physiological acidification due to CO2 retention, mainly in the branchial cavity. Individuals of six populations were collected along the coastline of Chile and were exposed to air for different time periods in the laboratory. The following parameters were measured: pH, Ca2+, Cl- and haemolymphatic lactate dehydrogenase (LDH) enzyme activity. Populations from lower latitudes were significantly different from those from central and southern Chile, with a higher haemolymphatic pH variation and higher Ca2+ level, along with lower levels of Cl- and LDH enzyme activity. This indicates that the populations from lower latitudes, which are subject to higher air temperatures during emersion, have a higher homeostatic capacity during emersion periods than those of intermediate and higher latitudes. This response seems to be determined by genetic bases due to adaptation to the local environment.

Abstract: Ocean Acidification (OA) can have pervasive effects in calcifying marine organisms, and a better understanding of how different populations respond at the physiological and evolutionary level could help to model the impacts of global change in marine ecosystems. Due to its natural geography and oceanographic processes, the Chilean coast provides a natural laboratory where benthic organisms are frequently exposed to diverse projected OA scenarios. The goal of this study was to assess whether a population of mollusks thriving in a more variable environment (Talcaruca) would present higher phenotypic plasticity in physiological and morphological traits in response to different pCO(2) when compared to a population of the same species from a more stable environment (Los Molles). To achieve this, two benthic limpets (Scurria zebrina and Scurria viridula) inhabiting these two contrasting localities were exposed to ocean acidification experimental conditions representing the current pCO(2) in the Chilean coast (500 mu atm) and the levels predicted for the year 2100 in upwelling zones (1500 (mu atm). Our results show that the responses to OA are species-specific, even in this related species. Interestingly, S. viridula showed better performance under OA than S. zebrina (i.e., similar sizes and carbonate content in individuals from both populations; lower effects of acidification on the growth rate combined with a reduction of metabolism at higher pCO2). Remarkably, these characteristics could explain this species' success in overstepping the biogeographical break in the area of Talcaruca, which S. zebrina cannot achieve. Besides, the results show that the habitat factor has a strong influence on some traits. For instance, individuals from Talcaruca presented a higher growth rate plasticity index and lower shell dissolution rates in acidified conditions than those from Los Molles. These results show that limpets from the variable environment tend to display higher plasticity, buffering the physiological effects of OA compared with limpets from the more stable environment. Taken together, these findings highlight the key role of geographic variation in phenotypic plasticity to determine the vulnerability of calcifying organisms to future scenarios of OA.

Abstract: Geographically widespread species must cope with environmental differences between habitats. Information concerning geographic variations in response to climate variability is critical because many morphological, life history and physiological traits show variation across space. Reciprocal transplant experiments have shown to be relevant to evaluate the role of phenotypic plasticity and potential local adaptation in ecophysiological responses when coping with environmental variability. In this study, we characterize through reciprocal transplant experiments the reaction norms of morphological, biochemical, physiological and life-history traits between two intertidal populations of the socioeconomically important mussel Mytilus chilensis, inhabiting contrasting local environments (estuarine vs coastal habitats). We found a gradient in phenotypic plasticity with plastic trait responses in metabolic, ingestion and clearance rates, and in HsP(70) gene expression, and some traits with responses more canalized as growth and calcification rates. This emphasizes that responses not only vary across different local populations but also in different traits in M. chilensis, thus it is difficult to establish an overall trend of the responses at integrated organismal level. Moreover, the synergistic interaction of factors such as salinity and carbonate system parameters evaluated make it necessary to study the response at the population level with emphasis on benthic species important in aquaculture. Finally, field studies such as this one are useful for documenting the patterns of traits variation that occur in nature, identifying possible causes of such variation, and generating testable hypotheses for future controlled experiments. (C) 2017 Elsevier B.V. All rights reserved.

Abstract: The present study explores the feasibility of the accumulation of polyhydroxyalkanoates (PHAs) under the presence of transient concentrations of added sodium chloride, by means of a mixed microbial culture (MMC). This culture was enriched on a mixture of volatile fatty acids (VFAs) containing 0.8 g Na+/L, as NaOH. This MMC presented a maximum PHA accumulation capacity of 53 wt% with 27 Cmol% HV. Accumulation experiments performed with added NaCI at concentrations of 7, 13 and 20 g/L shown that this salt provoked a decrease of the biomass PHA production rate, with an IC50 value close to 7 g NaCl/L. The accumulated PHA was lower than the corresponding value of the assay without the addition of salt. Furthermore, the composition of the biopolymer, in terms of HB:HV ratio, changed from 2.71 to 6.37 Cmol/Cmol, which means a HV decrease between 27 and 14 Cmol%. Summarizing, the PHA accumulation by a MMC non-adapted to saline conditions affected the polymer composition and lead to lower production yields and rates than in absence of added NaCl. (C) 2015 Elsevier B.V. All rights reserved.

Abstract: The application of autotrophic nitrogen removal processes in the main line of wastewater treatment plants will contribute to achieve its self-energy-sufficiency. However, the effective suppression of nitrite oxidizing bacteria (NOB) activity at the conditions of low temperature and low ammonium concentration (mainstream conditions) was identified as one of the main bottlenecks. In this study, stable partial nitritation at 16 degrees C and 50 mg NH4+-N/L was achieved maintaining inside the reactor free nitrous acid (FNA) concentrations inhibitory for NOB (>0.02 mg HNO2-N/L), without dissolved oxygen concentration control, The FNA inhibitory concentration was generated by the partial nitritation process, and its stimulation was studied with two different inhibitors: sodium azide and nitrite. The microbiological analysis revealed that, throughout the operational period with inhibitory FNA levels, the NOB populations (dominated by Nitrospira) were effectively washed out from the reactor. This is an advantage that allowed maintaining a good stability of the process, even when the FNA concentration was not enough to inhibit the NOB, taking about 40 days to develop significant activity. The observed delay on the NOB development is expected to enable the establishment of corrective actions to avoid the partial nitritation destabilization. The use of the FNA to achieve a stable partial nitritation process is recommended to profit from the natural pH decrease associated to the nitritation process and from its favoured accumulation at low temperatures as those from the mainstream. In this research study an analysis about the influence of ammonium and alkalinity concentrations was also performed to know in which scenarios the FNA inhibitory concentration can be achieved. (C) 2017 Elsevier B.V. All rights reserved.

Abstract: Along the west coast of South America, from the tropical zone to the Patagonian waters, there is a significant latitudinal gradient in seawater temperature, salinity and carbonate chemistry. These physical-chemical changes in seawater induce morphological and physiological responses in calcifying organisms, which may alter their energy budget and calcification processes. In this study, we study the organism energy maintenance (i.e. metabolic rate) and mineralogical composition of the shell of the juvenile marine snails Concholepas concholepas (Gastropoda: Muricidae), collected from benthic populations located similar to 2000km apart, varies across geographic regions along the Chilean coast. We found that in juvenile snails, the calcite:aragonite ratio in the pallial shell margin (i.e. newly deposited shell) increase significantly from northern to southern populations and this increase in calcite precipitation in the shell of juveniles snails was associated with a decrease in oxygen consumption rates in these populations. Our result suggests that calcite secretion may be favoured when metabolic rates are lowered, as this carbonate mineral phase might be less energetically costly for the organism to precipitate. This result is discussed in relation to the natural process such as coastal upwelling and freshwater inputs that promote geographic variation in levels of pH and carbonate saturation state in seawater along the Chilean coast.

Abstract: The assessment of the effects of Ocean Acidification (OA) on marine life has received increasing attention in recent marine research. On a mesocosmic scale, the CO2 levels in seawater can be manipulated to evaluate experimentally the consequences of OA on marine organisms (vertebrates and invertebrates). An ideal manipulation of carbonate chemistry should mimic exactly the changes to carbonate chemistry, which will occur in years to come. Although some methods have been described in the literature, here we describe in detail a simple, robust and inexpensive system to produce CO2-enriched seawater by bubbling the seawater with air-CO2 mixtures. The system uses mass flow controllers (MFC) to blend atmospheric air with pure CO2 to produce two pCO(2) levels. The air-CO2 mixtures are delivered continuously to seawater equilibration reservoirs, and simultaneously to an infrared CO2 analyser to verify CO2 levels in the air-CO2 mixture delivered to the equilibration tanks. We monitored both pH and total alkalinity in the equilibration reservoirs over a period of one year in order to document the long-term performance of this system for simulating the future carbonate chemistry of seawater in a coastal laboratory. System performance was sufficient to maintain three contrasting (e.g., 397, 709 and 1032 matm) and relatively constant (the coefficient of variability was 11 %, 9 % and 9 % respectively) seawater pCO(2) during a year-long monitoring.