Kinetics of phenol biodegradation at high concentration by a metabolically versatile isolated yeast Candida tropicalis PHB5

A highly tolerant phenol-degrading yeast strain PHB5 was isolated from wastewater effluent of a coke oven plant and identified as Candida tropicalis based on phylogenetic analysis. Biodegradation experiments with C. tropicalis PHB5 showed that the strain was able to utilize 99.4 % of 2,400 mg l^?1 phenol as sole source of carbon and energy within 48 h. Strain PHB5 was also observed to grow on 18 various aromatic hydrocarbons. Haldane model was used to fit the exponential growth data and the following kinetic parameters were obtained: μ _max?=?0.3407 h^?1, K _S?=?15.81 mg l^?1, K _i?=?169.0 mg l^?1 (R ²?=?0.9886). The true specific growth rate, calculated from μ _max, was 0.2113. A volumetric phenol degradation rate (V _max) was calculated by fitting the phenol consumption data with Gompertz model and specific degradation rate (q) was calculated from V _max. The q values were fitted with Haldane model, yielding following parameters: q _max?=?0.2766 g g^?1 h^?1, K _S ′?=?2.819 mg l^?1, K _i ′?=?2,093 (R ²?=?0.8176). The yield factor (Y _X/S ) varied between 0.185 to 0.96 g g^?1 for different initial phenol concentrations. Phenol degradation by the strain proceeded through a pathway involving production of intermediates such as catechol and cis,cis-muconic acid which were identified by enzymatic assays and HPLC analysis.     

Dissolved Organic Carbon and Estrogen Transport in Surface Runoff From Agricultural Land Receiving Poultry Litter1

Dutta, Sudarshan, Shreeram Inamdar, Jerry Tso, Diana S. Aga, and J. Tom Sims, 2012. Dissolved Organic Carbon and Estrogen Transport in Surface Runoff from Agricultural Land Receiving Poultry Litter. Journal of the American Water Resources Association (JAWRA) 48(3): 558-569. DOI: 10.1111/j.1752-1688.2011.00634.x Abstract: Dissolved organic carbon (DOC) provides a reactive substrate for the transport of organic contaminants with runoff. Very few studies have investigated the export of DOC from agricultural land, especially those receiving manure applications. We investigated exports of DOC in surface runoff from agricultural fields receiving various treatments of poultry litter (raw vs. pelletized). In addition, we also investigated how estrogens in runoff were associated with DOC. Different forms of estrogens studied were: estrone, 17β-estradiol, estriol, and their conjugates. Experimental agricultural plots were 12 m × 5 m long and had reduced tillage and no-till management practices. The aromatic content of DOC was characterized using specific ultraviolet absorbance (SUVA). Flow-weighted concentrations of DOC and SUVA in surface runoff from plots with poultry litter were significantly (p ≤ 0.10) greater than the control (no litter) plots. Compared to pelletized poultry litter, reduced-tillage plots with raw litter yielded higher DOC concentrations and SUVA values. No significant differences (p ≥ 0.10) in DOC and SUVA were observed between litter treatments for plots with no-till. Total estrogen concentrations (including all forms) were positively and significantly (p ≤ 0.10) correlated with DOC. These results can help select and guide agricultural management practices that can reduce the exports of DOC and associated contaminant from agricultural land receiving manure applications.     

Nanotechnology applications in pollution sensing and degradation in agriculture: a review

With the rise in the global population, the demand for increased supply of food has motivated scientists and engineers to design new methods to boost agricultural production. With limited availability of land and water resources, growth in agriculture can be achieved only by increasing productivity through good agronomy and supporting it with an effective use of modern technology. Advanced agronomical methods lay stress not only on boosting agricultural produce through use of more effective fertilizers and pesticides, but also on the hygienic storage of agricultural produce. The detrimental effects of modern agricultural methods on the ecosystem have raised serious concerns amongst environmentalists. The widespread use of persistent pesticides globally over the last six decades has contaminated groundwater and soil, resulting in diseases and hardships in non-target species such as humans and animals. The first step in the removal of disease causing microbes from food products or harmful contaminants from soil and groundwater is the effective detection of these damaging elements. Nanotechnology offers a lot of promise in the area of pollution sensing and prevention, by exploiting novel properties of nanomaterials. Nanotechnology can augment agricultural production and boost food processing industry through applications of these unique properties. Nanosensors are capable of detecting microbes, humidity and toxic pollutants at very minute levels. Organic pesticides and industrial pollutants can be degraded into harmless and often useful components, through a process called photocatalysis using metal oxide semiconductor nanostructures. Nanotechnology is gradually moving out from the experimental into the practical regime and is making its presence felt in agriculture and the food processing industry. Here we review the contributions of nanotechnology to the sensing and degradation of pollutants for improved agricultural production with sustainable environmental protection.     

Synthesizing habitat connectivity analyses of a globally important human-dominated tiger-conservation landscape

As ecological data and associated analyses become more widely available, synthesizing results for effective communication with stakeholders is essential. In the case of wildlife corridors, managers in human-dominated landscapes need to identify both the locations of corridors and multiple stakeholders for effective oversight. We synthesized five independent studies of tiger (Panthera tigris) connectivity in central India, a global priority landscape for tiger conservation, to quantify agreement on landscape permeability for tiger movement and potential movement pathways. We used the latter analysis to identify connectivity areas on which studies agreed and stakeholders associated with these areas to determine relevant participants in corridor management. Three or more of the five studies’ resistance layers agreed in 63% of the study area. Areas in which all studies agree on resistance were of primarily low (66%, e.g., forest) and high (24%, e.g., urban) resistance. Agreement was lower in intermediate resistance areas (e.g., agriculture). Despite these differences, the studies largely agreed on areas with high levels of potential movement: >40% of high average (top 20%) current-flow pixels were also in the top 20% of current-flow agreement pixels (measured by low variation), indicating consensus connectivity areas (CCAs) as conservation priorities. Roughly 70% of the CCAs fell within village administrative boundaries, and 100% overlapped forest department management boundaries, suggesting that people live and use forests within these priority areas. Over 16% of total CCAs’ area was within 1 km of linear infrastructure (437 road, 170 railway, 179 transmission line, and 339 canal crossings; 105 mines within 1 km of CCAs). In 2019, 78% of forest land diversions for infrastructure and mining in Madhya Pradesh (which comprises most of the study region) took place in districts with CCAs. Acute competition for land in this landscape with globally important wildlife corridors calls for an effective comanagement strategy involving local communities, forest departments, and infrastructure planners.     

In situ biofilm barriers: Case study of a nitrate groundwater plume,Albuquerque, New Mexico

A new use for biofilm barriers was developed and successfully applied to treat nitrate‐contaminated groundwater down to drinking water standards. The barrier was created by stimulating indigenous bacteria with injections of molasses as the carbon donor and a combination of yeast extract and trimetaphosphate as nutrients. This injection of amendments results in bacterial growth in the aquifer, which attaches to the sand grains to create a reactive semipermeable biofilm. The biofilm barrier presented in this article reduced the migration of contaminants and provided an active zone for remediation. The cylindrical biobarrier was constructed using eight wells on the perimeter forming a 60‐foot‐diameter reactive biodenitrification region. Another well at the center was installed to continuously extract the treated water. The intent was to produce a continuous source of nitrate‐free water. The system operated for over one year, and during this period, the biobarrier was revived multiple times by reinjecting molasses in the perimeter wells. Nitrate concentrations of treated water decreased from 275 mg/L (as nitrogen) to < 1 mg/L. © 2005 Wiley Periodicals, Inc.     

Effect of manganese toxicity on pigment content,Hill activity and photosynthetic rate of Vigna radiata L. Wilczek seedlings

Effect of different concentrations, viz. 10(-4) M, 5 x 10(-4) M, 10(-3) M and 5 x 10(-3) M of manganese sulphate (MnSO4, 7H2O) on chlorophyll, carotenoid pigment content and photosynthesis of mungbean seedlings was examined Progressive increase in manganese sulphate concentration upto 5 x 10(-3) M brought about a progressive decrease in total chlorophyll and chl a content. Chl b content changed very little by excess manganese treatment. Total carotenoid pigment content decreased considerably in comparison to control with every concentration of manganese sulphate tried here. Hill activity of chloroplasts isolated from leaves of mungbean seedling and rate of photosynthesis in terms of CO2 uptake showed progressive reduction along with the increase in concentration of the manganese.     

Degradation of atrazine in mineral salts medium and soil using enrichment culture

Atrazine degrading enrichment culture was prepared by its repeated addition to an alluvial soil and its ability to degrade atrazine in mineral salts medium and soil was studied. Enrichment culture utilized atrazine as a sole source of carbon and nitrogen in mineral salts medium and degradation slowed down when sucrose and/or ammonium hydrogen phosphate were supplemented as additional source of carbon and nitrogen, respectively. Biuret was detected as the only metabolite of atrazine while deethylatrazine, deisopropyatrazine, hydroxyatrazine and cyanuric acid were never detected at any stage of degradation. Enrichment culture degraded atrazine in an alkaline alluvial soil while no degradation was observed in the acidic laterite soil. Enrichment culture was able to withstand high concentrations of atrazine (110 μg/g) in the alluvial soil as atrazine was completely degraded. Developed mixed culture has the ability to degrade atrazine and has potential application in decontamination of contaminated water and soil.