Kinetics of phenol degradation using Pseudomonas putida MTCC 1194

Pseudomonas putida (MTCC 1194) has been used to degrade phenol in water in the concentration range 100–1000?ppm. The inhibition effects of phenol as substrate have become predominant above the concentration of 500?ppm (5.31?mmoles/dm³). The optimum temperature and initial pH required for maximum phenol biodegradation were 30?°C and 7.00 respectively. From the degradation data the activation energy (E _a ) was found to be equal to 13.8?kcal/g mole substrate reacted. The most suitable inoculum age and volume for highest phenol degradation were 12?hrs and 7% v/v respectively. Surfactants had negligible effect on phenol biodegradation process for this microorganism. Monod model has been used to interpret the free cell data on phenol biodegradation. The kinetic parameters have been estimated upto initial concentration of 5.31?mmoles/dm³. μ _max and K _S gradually increased with higher concentration of phenol. However, beyond the phenol concentration of 5.31?mmoles/dm³, the inhibition became prominant. The μ _max has been to be a strong function of initial phenol concentration. The simulated and the experimental phenol degradation profiles have good correspondence with each other.     

Evaluation of PAHs concentration and cancer risk assessment on human health in a roadside soil: A case study

Abstract

An explanatory study was carried out to divulge the sources, contamination level of different classes of Polycyclic Aromatic Hydrocarbons (PAHs) distribution and the impact of vehicular traffic on the roadside soil by assessing incremental lifetime cancer risk at each site to understand the potential health risk of nearby residents along the National Highway-2 Delhi–Kolkata India. Comparison of the cancer risk assessment was performed using Monte Carlo simulation for the entire study area. The results revealed 90% cancer risk value of 6.40?×?10^?5 and 6.5?×?10^?5 for children and adults, respectively, whereas, without simulation the Total Cancer Risk (TCR) for adults was 6.925?×?10^?5 and 6.220?×?10^?5 for children, observed maximum at the location (S5). The dilemma of risk assessment indicating profoundly contaminated soil. Comparison of PAHs concentration with the background values of PAHs ranged from 1.478 to 27.493?mg kg^?1. The (IP/BgP) ratio specified that the PAHs content of the highway roadside sample is preponderate by diesel vehicle emission, biomass combustion and coal combustion. The study clearly revealed and advocated the influence of organic and inorganic pollution, which aggravates and causes health issues to the nearby inhabitants. This study could also be advantageous to similar consequences seen elsewhere in the world.     

Berberine–DNA complexation: New insights into the cooperative binding and energetic aspects

The equilibrium binding of the cytotoxic plant alkaloid berberine to various DNAs and energetics of the interaction have been studied. At low ratios of bound alkaloid to base pair, the binding exhibited cooperativity to natural DNAs having almost equal proportions of AT and GC sequences. In contrast, the binding was non-cooperative to DNAs with predominantly high AT or GC sequences. Among the synthetic DNAs, cooperative binding was observed with poly(dA).poly(dT) and poly(dG).poly(dC) while non-cooperative binding was seen with poly(dA–dT).poly(dA–dT) and poly(dG–dC).poly(dG–dC). Both cooperative and non-cooperative bindings were remarkably dependent on the salt concentration of the media. Linear plots of ln K_a versus [Na⁺] for poly(dA).poly(dT) and poly(dA–dT).poly(dA–dT) showed the release of 0.56 and 0.75 sodium ions respectively per bound alkaloid. Isothermal titration calorimetry results revealed the binding to be exothermic and favoured by both enthalpy and entropy changes in all DNAs except the two AT polymers and AT rich DNA, where the same was predominantly entropy driven. Heat capacity values (ΔCp^o) of berberine binding to poly(dA).poly(dT), poly(dA–dT).poly(dA–dT), Clostridium perfringens and calf thymus DNA were − 98, − 140, − 120 and − 110 cal/mol K respectively. This study presents new insights into the binding dependent base pair heterogeneity in DNA conformation and the first complete thermodynamic profile of berberine binding to DNAs.     

Optimizing tillage schedule for maintaining activity of the arbuscular mycorrhizal fungal population in a rainfed upland rice (Oryza sativa L.) agro-ecosystem

Rainfed uplands in India are predominantly mono-cropped with rice (Oryza sativa L.) in the wet season (June/July to September/October) and grown under aerobic soil conditions. The remaining fallow period (winter followed by summer) of about 8–9 months leads to natural crash in the population of native arbuscular mycorrhizal fungi (AMF) in the soil. Attempts have been made to minimize this population crash by reducing soil disturbance-induced deleterious effects on native AMF activity of improperly scheduled off-season tillage, an agronomic recommendation for weed and disease (soil-borne) management, practiced by the upland farmers. On-farm (farmers' field) evaluation of effects of all suitable off-season tillage schedule combinations on rice during wet seasons of 2004, 2005, and 2006 revealed that a maximum of two off-season tillage schedules with a minimum gap of 13 weeks between them minimized the population crash of native AMF with a concomitant increase in phosphorus (P) uptake and grain yield of upland rice (variety “Vandana”).     

Differential binding of peanut agglutinin with lipopolysaccharide of homologous and heterologous Rhizobium

Abstract To establish the crucial role of lipopolysaccharide in the initial recognition event of symbiotic peanut-Rhizobium system the ability of various surface polysaccharides isolated from Bradyrhizobium arachis to inhibit the precipitin reaction between peanut agglutinin and asialoganglioside: deoxycholate (1:1) micelles was estimated. It was compared with that of nonsymbiotic systems e.g. Bradyrhizobium japonicum, Bradyrhizobium ciceris and Escherichia coli . Peanut agglutinin was found to interact more strongly with the lipopolysaccharide of Bradyrhizobium arachis than the exopolysaccharide or capsular polysaccharide. The inhibitory capacity of lipopolysaccharides from homologous and heterologous Bradyrhizobium as measured in terms of the concentration necessary for 50 percent inhibition of precipitin reaction were 1428, 500, 410, and 277 times less than that of lactose for Bradyrhizobium arachis, B. japonicum, B. ciceris and Escherichia coli , respectively. These results support that host lectin peanut agglutinin can recognize homologous Bradyrhizobium lipopolysaccharide by virtue of its binding specificity of higher magnitude.     

Identification and assessment of genetic relationships in three <Emphasis Type="Italic">Chlorophytum</Emphasis> species and two high yielding genotypes of <Emphasis Type="Italic">C. borivilianum</Emphasis> through RAPD markers

Conservation of identified germplasm is an important component for efficient and effective management of plant genetic resources. Since Chlorophytum species are important medicinal plants, studies were carried out for identification and establish genetic relationships in three species of Chlorophytum and two high yielding genotypes of Chlorophtum borivilianum using RAPD markers. Out of one hundred primers tested, 47 decamers amplified a total of 454 distinct bands ranging from 0.25–3.0 kbp to identify and to evaluate genetic relationships between and among three species of Chlorophytum and two genotypes of Chlorophtum borivilianum. The cluster analysis indicated that three species of Chlorophytum and two genotypes (NRCCB-1 and NRCCB-2) of C. borivilianum formed two major clusters. The first major cluster constituted C. arundinaceum and C. tuberosum, and the second major cluster composed of two subclusters; the first subcluster represented NRCB-1 and NRCB-2 where as the second subcluster represented C. borivilianum. Thus, the RAPD markers have the potential for identification and characterization of genetic relatedness among the species and genotypes. C. borivilianum along with two genotypes also showed similar banding patterns which could be chosen as candidate markers for differentiating the other two species such as C. arundinaceum and C. tuberosum. This would helpful for breeding programmes and provides an important input in conservation biology.     

Commentary on: Calpain-2 participates in the process of calpain-1 inactivation

Calpain belongs to the calcium-dependent non-lysosomal cysteine protease. Calpain-1 (C1) and calpain-2 (C2) expression are ubiquitous in mammals and an important mediator of the action of calcium. Specific substrate cleavage by C1 and C2 is critical for several calcium-dependent cellular pathways including neuronal function, muscle contraction, signal transduction, cell differentiation, proliferation, and apoptosis. Research suggests that C1 and C2 perform similar functions due to their structurally highly similar isoforms. Increasing evidence suggests that C1 and C2 carry out their specific function in vivo. A recent paper published by Shinkai-Ouchi et al. (Bioscience Reports (2020) 40, DOI: 10.1042/BSR20200552) elucidated the mechanism to differentiate the function of each calpain with respect to the efficiency and longevity for proteolysis after activation. Further, the study represented that C1 and C2 do not synergistically perform their work in vitro. On the other hand, the activity of C1 is reduced in presence of C2. This insight establishes the platform for future studies to examine how C2 regulates the C1 for substrate proteolysis.     

L-Phenylalanine production by double auxotrophic analogue resistant mutants of Arthrobacter globiformis

A number of tryptophan plus tyrosine double auxotrophic mutants isolated by the NTG treatment of a glutamate producing strain of Arthrobacter globiformis were found to excrete phenylalanine in a mineral salt medium. By controlling the pH of the medium to near neutrality, the active growth period could be extended up to 72 h and more phenylalanine was accumulated compared to the unregulated culture where the growth period took up to 48 h. Under optimum culture conditions, the best double auxotroph (TT-39) produced 3 g phenylalanine/l. Further improvement of phenylalanine production has been achieved by the step-by-step isolation of a mutant resistant to the phenylalanine analogues p-fluorophenylalanine (PFP) and β-2-thienylalanine (TA) from the TT-39 strain. Under optimum culture conditions, the best double auxotrophic analogue resistant mutant TT-39 PT^r-21 yielded 8.7 g/l phenylalanine.