Multipurpose cellulases of Promicromonospora sp. VP111, with broad substrate specificity and tolerance properties.

Cellulolytic actinobacterium, Promicromonospora sp. VP111 concomitantly produced cellulases (CELs), xylanase and pectinase when grown on commercial cellulose and untreated agricultural lignocellulosic residues (wheat straw and sugarcane bagasse). Secreted CELs hydrolyzed (enhanced with Co2+ ion) multiple cellulosic substrates, including sodium carboxymethyl cellulose (Na-CMC), Whatman filter paper no. 1, microcrystalline cellulose (avicel), p-nitrophenyl-ß-D-glucopyranoside (pNPG), laminarin, and cellulose powder. The CELs showed stabilities in the presence of various chemicals, including glucose (0.2 M), detergents (1%, w/v or v/v), denaturants (1%, w/v or v/v), and sodium chloride (NaCl, 30%, w/v). The CELs were fractionated using ammonium sulfate precipitation and dialysis. Activities (%) of fractionated CELs were retained at 60°C for endoglucanase/carboxymethyl cellulase (CMCase) (88.38), filter paper cellulase (FPase) (77.55), and ß-glucosidase (90.52), which indicated of thermo-stability. Similarly, the activities (%) for CMCase (85.79), FPase (82.48), and ß-glucosidase (85.92) at pH 8.5 indicated of alkaline-stability. Kinetic factors, Km and Vmax for endoglucanase component of fractionated CELs were 0.014 g/l and 158.23 µM glucose/min/mL, respectively. Fractionated CELs yielded activation energies (kJ/mol) of 17.933, 6.294, and 4.207 for CMCase, FPase, and ß-glucosidase activities, respectively in linear thermostable Arrhenius plots. Thus, this study reports on the multipurpose CELs from an untreated agricultural residue utilizing Promicromonospora in relation to broad substrate specificity, halo-tolerance, alkaline-tolerance, detergent-tolerance, thermo-tolerance, organic solvent-tolerance, and end product-tolerance.

Study of As-resistant bacteria from Nadia, India and a survey of two As resistance-related proteins.

The present investigation deals with the characterisation of three As-resistant bacteria, Bacillus aryabhattai strain VPS1, Bacillus licheniformis strain VPS6 and Sporosarcina thermotolerans strain VPS7 isolated from the rhizosphere of a contaminated paddy field in Chakdaha, Nadia, West Bengal, India. Two strains, VPS6 and VPS7 showed ureolytic activity, which can be used for microbial-induced calcite precipitation of As as a bioremediation option. However, As reduction and oxidation capacities were not reported in any of these bacteria. A phylogenetic tree of 16S ribosomal RNA gene sequences was constructed for all three bacterial isolates, including different species of As-resistant Bacillus and Sporosarcina. Furthermore, literature survey and genome mining were employed to explore the diversity of As resistance-related proteins, arsenite S-adenosylmethyltransferase (ArsM) and arsenical pump membrane protein (ArsB) among different bacteria, and the phylogenetic relatedness was studied to understand the distribution and evolution of their amino acid sequences. ArsB was predominantly present in a wide variety of bacteria (347 taxa); however, ArsM was reported in comparatively fewer isolates (109 taxa). There were a total of 60 similar taxa that contained both ArsM and ArsB. Both proteins were most abundantly present in phylum Proteobacteria. Overall, this investigation enumerates As-resistant bacteria to understand the As metabolism in the environment, and the phylogenetic analysis of As resistance-related proteins helps in understanding the functional relationship in different bacteria for their role in As mobility in the environment.

Communication: Coherences observed in vivo in photosynthetic bacteria using two-dimensional electronic spectroscopy.

Energy transfer through large disordered antenna networks in photosynthetic organisms can occur with a quantum efficiency of nearly 100%. This energy transfer is facilitated by the electronic structure of the photosynthetic antennae as well as interactions between electronic states and the surrounding environment. Coherences in time-domain spectroscopy provide a fine probe of how a system interacts with its surroundings. In two-dimensional electronic spectroscopy, coherences can appear on both the ground and excited state surfaces revealing detailed information regarding electronic structure, system-bath coupling, energy transfer, and energetic coupling in complex chemical systems. Numerous studies have revealed coherences in isolated photosynthetic pigment-protein complexes, but these coherences have not been observed in vivo due to the small amplitude of these signals and the intense scatter from whole cells. Here, we present data acquired using ultrafast video-acquisition gradient-assisted photon echo spectroscopy to observe quantum beating signals from coherences in vivo. Experiments were conducted on isolated light harvesting complex II (LH2) from Rhodobacter sphaeroides, whole cells of R. sphaeroides, and whole cells of R. sphaeroides grown in 30% deuterated media. A vibronic coherence was observed following laser excitation at ambient temperature between the B850 and the B850(∗) states of LH2 in each of the 3 samples with a lifetime of ∼40-60 fs.

Dynamic localization of electronic excitation in photosynthetic complexes revealed with chiral two-dimensional spectroscopy.

Time-resolved ultrafast optical probes of chiral dynamics provide a new window allowing us to explore how interactions with such structured environments drive electronic dynamics. Incorporating optical activity into time-resolved spectroscopies has proven challenging because of the small signal and large achiral background. Here we demonstrate that two-dimensional electronic spectroscopy can be adapted to detect chiral signals and that these signals reveal how excitations delocalize and contract following excitation. We dynamically probe the evolution of chiral electronic structure in the light-harvesting complex 2 of purple bacteria following photoexcitation by creating a chiral two-dimensional mapping. The dynamics of the chiral two-dimensional signal directly reports on changes in the degree of delocalization of the excitonic states following photoexcitation. The mechanism of energy transfer in this system may enhance transfer probability because of the coherent coupling among chromophores while suppressing fluorescence that arises from populating delocalized states. This generally applicable spectroscopy will provide an incisive tool to probe ultrafast transient molecular fluctuations that are obscured in non-chiral experiments.

Probing energy transfer events in the light harvesting complex 2 (LH2) of Rhodobacter sphaeroides with two-dimensional spectroscopy.

Excitation energy transfer events in the photosynthetic light harvesting complex 2 (LH2) of Rhodobacter sphaeroides are investigated with polarization controlled two-dimensional electronic spectroscopy. A spectrally broadened pulse allows simultaneous measurement of the energy transfer within and between the two absorption bands at 800 nm and 850 nm. The phased all-parallel polarization two-dimensional spectra resolve the initial events of energy transfer by separating the intra-band and inter-band relaxation processes across the two-dimensional map. The internal dynamics of the 800 nm region of the spectra are resolved as a cross peak that grows in on an ultrafast time scale, reflecting energy transfer between higher lying excitations of the B850 chromophores into the B800 states. We utilize a polarization sequence designed to highlight the initial excited state dynamics which uncovers an ultrafast transfer component between the two bands that was not observed in the all-parallel polarization data. We attribute the ultrafast transfer component to energy transfer from higher energy exciton states to lower energy states of the strongly coupled B850 chromophores. Connecting the spectroscopic signature to the molecular structure, we reveal multiple relaxation pathways including a cyclic transfer of energy between the two rings of the complex.

Timescales of Coherent Dynamics in the Light Harvesting Complex 2 (LH2) of Rhodobacter sphaeroides.

The initial dynamics of energy transfer in the light harvesting complex 2 from Rhodobacter sphaeroides were investigated with polarization controlled two-dimensional spectroscopy. This method allows only the coherent electronic motions to be observed revealing the timescale of dephasing among the excited states. We observe persistent coherence among all states and assign ensemble dephasing rates for the various coherences. A simple model is utilized to connect the spectroscopic transitions to the molecular structure, allowing us to distinguish coherences between the two rings of chromophores and coherences within the rings. We also compare dephasing rates between excited states to dephasing rates between the ground and excited states, revealing that the coherences between excited states dephase on a slower timescale than coherences between the ground and excited states.

Association between indoor fungi in Delhi homes and sensitization in children with respiratory allergy.

Indoor fungi are potential sensitizing agents in children and their detection and quantification in indoor air are important in the diagnosis and environmental management of fungal allergies. The objective of this investigation was to assess the prevalence of fungal allergies in children in Delhi and to study the association between mold counts in the homes of children and their sensitization to respective fungal extracts. Fungal concentrations and seasonality were studied at two-week intervals for one year using Andersen Volumetric and Burkard Slide samplers. Sensitization to fungi frequently encountered in patients' homes was assessed by Skin Prick Tests (SPTs). Total fungal specific IgE was measured by ELISA in the sera of patients positive to fungal extracts. Skin Prick Tests revealed that 39.3% (33/84) of patients were markedly positive (2 + and above) to one or the other fungal allergens. Raised serum IgE to predominant indoor fungal species was observed in patients with marked SPT results. Highest marked skin reactivity (2 + and above) was obtained with Alternaria alternata allergens in 17.9% of the children, which was followed by the response to fungal antigens of Aspergillus fumigatus and Penicillium citrinum (15.5%). Exposure to high fungal counts of some dominant fungi (Penicillium, A. nidulans and A. fumigatus) was found associated with increased fungal sensitization in the patients. Total serum IgE level was revealed to be significantly linked with the intensity of skin reactions, as well as with skin index (r(2) = 0.052; P < 0.05). We concluded that children in Delhi are exposed to high concentrations of fungi in the indoor environment and that respiratory allergies were connected with higher prevalence of skin sensitization.

Indoor fungal concentration in the homes of allergic/asthmatic children in Delhi, India.

Allergy to fungi has been linked to a wide range of illnesses, including rhinitis and asthma. Therefore, exposure to fungi in home environment is an important factor for fungal allergy. The present study was aimed to investigate types of airborne fungi inside and outside the homes of asthmatic children and control subjects (nonasthmatic children). The dominant fungi were evaluated for their quantitative distribution and seasonal variation. The air samples were collected from indoors and immediate outdoors of 77 selected homes of children suffering from bronchial asthma/allergic rhinitis using Andersen volumetric air sampler. The isolated fungal genera/species were identified using reference literature, and statistical analysis of the dominant fungi was performed to study the difference in fungal concentration between indoor and immediate outdoor sites as well as in between different seasons. A total of 4423 air samples were collected from two indoor and immediate outdoor sites in a 1-year survey of 77 homes. This resulted in the isolation of an average of 110,091 and 107,070 fungal colonies per metric cube of air from indoor and outdoor sites, respectively. A total of 68 different molds were identified. Different species of Aspergillus, Alternaria, Cladosporium, and Penicillium were found to be the most prevalent fungi in Delhi homes, which constituted 88.6% of the total colonies indoors. Highest concentration was registered in autumn and winter months. Total as well as dominant fungi displayed statistically significant differences among the four seasons (p < 0.001). The largest number of isolations were the species of Aspergillus (>40% to total colony-forming units in indoors as well as outdoors) followed by Cladosporium spp. Annual concentration of Aspergillus spp. was significantly higher (p < 0.05) inside the homes when compared with outdoors. Most of the fungi also occurred at a significantly higher (p < 0.001) rate inside the homes when compared with immediate outdoors. Asthmatic children in Delhi are exposed to a substantial concentration of mold inside their homes as well as immediate outdoor air. The considerable seasonal distributions of fungi provide valuable data for investigation of the role of fungal exposure as a risk for respiratory disorders among patients suffering from allergy or asthma in Delhi.