Nitrogen and sulfur functionalized microporous carbon nanomaterial derived from waste coconut husk for the efficient detection and removal of ofloxacin.

This study uses waste coconut husk to synthesize carbon quantum dots decorated graphene-like structure for sustainable detection and removal of ofloxacin. The XRD spectrum shows the carbon nanomaterial's layered structure with turbostratic carbon stacking on its surface. The FESEM and HRTEM studies claim the successful development of quantum dots decorated 2D layered structure of carbon nanomaterial. The functionalization of sulfur and nitrogen is well observed and studied through XPS, while Raman spectra have provided insight into the surface topology of the as-synthesized nanostructure. The BET surface area was found to be 1437.12 m2/g with a microporous structure (pore width 2.0 nm) which interestingly outcompete many reported carbon-based nanomaterials such as graphene oxide, reduced graphene oxide and quantum dots. The detection and removal processes are monitored through UV-visible spectroscopy and the obtained detection limit and adsorption capacity were 2.7 nM and 393.94 mg/L respectively. Additionally, 1 mg carbon nanomaterial has removed 49 % ofloxacin from water in just 1 h. In this way, this study has successfully managed the coconut husk waste after its utilization for environmental remediation purposes.

Comparison of Antimicrobial Activity of Triple, Double, and Cefixime-Based Antibiotic Pastes Against Enterococcus Faecalis: An In Vitro Study.

AIM: This in vitro study aims to compare the antimicrobial efficacy of triple antibiotic paste, double antibiotic paste, and cefixime-based triple antibiotic paste against Enterococcus faecalis. Materials and methods: Fifty single-rooted, caries-free, permanent teeth without any developmental defects were included in this study. The specimens were divided into five groups, with each group consisting of 10 teeth that received a specific medicament. The groups were as follows: Group I: control; Group II: calcium hydroxide; Group III: triple antibiotic paste; Group IV: double antibiotic paste; and Group V: cefixime-based triple antibiotic paste. The antimicrobial activity of the medicaments was assessed against E. faecalis at the end of the seventh and 14th days. The colony-forming units (CFU) were calculated using the Kolmogorov-Smirnov and Wilcoxon tests. RESULTS: After seven days of the experimental process, it was observed that the CFU count was highest in group I and lowest in group V. In a similar vein, after 14 days, the maximum decrease in CFU count was observed in Group V, while the least reduction in CFU count was observed in Group II. On intergroup comparison, it was found that the maximum decrease in CFU was noted in Group V, followed by Group IV, Group III, and Group II. CONCLUSION: The study results indicated that the cefixime-enriched antibiotic paste had the greatest antimicrobial effectiveness, while the double and triple antibiotic pastes offered superior antibacterial efficacy against E. faecalis at the end of the seventh and 14th days.

Journal of family medicine and primary care- A five year bibliometric analysis from 2016 to 2020.

Aim: To conduct a five-year bibliometric analysis of the Journal of Family Medicine and Primary Care (J Family Med Prim Care) between 2016 and 2020. Setting and Design: This retrospective secondary data analysis was conducted in the Department of Conservative, Endodontics and Aesthetic Dentistry, Dental Institute, Rajendra Institute of Medical Sciences, Ranchi, Jharkhand and Rohilkhand Medical College and Hospital, Bareilly, UP. Material and Methods: The data of publications including research articles, review and case reports excluding editorials and letters to the editor, commentaries and invited articles published in the J Family Med Prim Care between 2016 and 2020 were downloaded from the journal website and analysed in terms of the bibliometric parameters. Results: The results revealed that the journal gave equal weightage to all types of articles. The total number of articles published between 2016 and 2020 was 2,426 out of which 1,666 articles were published from India and the remaining from other parts of the world. In India, the state of Delhi had the maximum publications while speciality Preventive and Social Medicine (22.42%) and General Medicine (23.12%) had the maximum articles. Moreover, between 2016 and 2020, J Family Med Prim Care had 2,132 citations of published articles and had 65 publications in 2020 about the Corona Virus Disease (COVID-19) pandemic. Conclusion: The issue numbers per year for J Family Med Prim Care has gradually increased over time. The publication is open for all fields of medical, dental sciences and allied sciences.

Prevalence of radix entomolaris in India and its comparison with the rest of the world.

INTRODUCTION: A successful endodontic treatment can be achieved by proper cleaning, shaping and disinfection and obturation of the root canal system. Mandibular molars requiring endodontic therapy have several variations. A mandibular molar usually has two roots but occasionally, it might have additional roots also. The purpose of this article is to determine the regional predilection of radix entomolaris in permanent mandibular first molar in India and its comparison to rest of world. EVIDENCE ACQUISITION: A search was undertaken to identify published research articles related to radix entomolaris in mandibular first molars. Sixty-four research articles were analyzed. EVIDENCE SYNTHESIS: Articles were assessed in relation to demographic location of radix entomolaris. Also, the type of study and the analytic tool employed for its assessment was evaluated. Results were tabulated and statistically analyzed. Statistical test revealed a significant variation between the India and rest of world. CONCLUSIONS: This research reported that regional predilection of radix entomolaris in mandibular first molar varies significantly. In India the highest incidence of radix entomolaris was observed in north India with 24%, whereas in world China reported the highest prevalence of 32% and the minimum was observed in Africa at 0%. India relied on conventional radiography for its diagnosis whereas rest of the world primarily utilized in-vitro studies and advanced radiography for its diagnosis.

Nonimmunogenic Hydrogel-Mediated Delivery of Antibiotics Outperforms Clinically Used Formulations in Mitigating Wound Infections.

Treatment of chronic wound infections caused by Gram-positive bacteria such as Staphylococcus aureus is highly challenging due to the low efficacy of existing formulations, thereby leading to drug resistance. Herein, we present the synthesis of a nonimmunogenic cholic acid-glycine-glycine conjugate (A6) that self-assembles into a supramolecular viscoelastic hydrogel (A6 gel) suitable for topical applications. The A6 hydrogel can entrap different antibiotics with high efficacy without compromising its viscoelastic behavior. Activities against different bacterial species using a disc diffusion assay demonstrated the antimicrobial effect of the ciprofloxacin-loaded A6 hydrogel (CPF-Gel). Immune profiling and gene expression studies after the application of the A6 gel to mice confirmed its nonimmunogenic nature to host tissues. We further demonstrated that topical application of CPF-Gel clears S. aureus-mediated wound infections more effectively than clinically used formulations. Therefore, cholic acid-derived hydrogels are an efficacious matrix for topical delivery of antibiotics and should be explored further.

Amelioration of short-term drought stress during different growth stages in Brassica juncea by rhizobacteria mediated maintenance of ROS homeostasis.

In the present investigation, the role of rhizobacteria in alleviating the deleterious effects of drought on mustard was assessed. The plants were exposed to short-term water shortages, during the vegetative and reproductive growth stages. Drought stress in both stages had a negative effect on growth, physiological, and biochemical parameters of mustard. Both the root and shoot biomass were significantly reduced in plants exposed to drought, but rhizobacterial inoculation resulted in better plant biomass than uninoculated plants. The ameliorative effects of inoculation were also indicated by improved relative water content, membrane stability index, total chlorophyll content, and photosynthetic parameters. Similarly, inoculation resulted in enhanced activity of antioxidative enzymes superoxide dismutase (SOD), ascorbate peroxidase, and catalase in both stages of growth which possibly increased stress tolerance by maintaining reactive oxygen species (ROS) homeostasis. There was a significant reduction in the accumulation of H2 O2 , proline and total soluble sugar in rhizobacteria treated plants under drought, suggesting that the treated plants did not encounter much stress and could maintain better plant health than uninoculated plants. Expression analysis of the BjP5CSB and BjFeSOD genes was conducted during both the growth stages. Expression of the BjP5CSB gene was significantly down-regulated in inoculated plants under drought, while BjFeSOD gene transcript levels were upregulated. The vegetative stage was more responsive to rhizobacterial inoculations than the reproductive stage under drought. Principal component analysis indicated a differential response by the two growth stages to inoculation. Hence, results indicate that these rhizobacteria reduce the negative impacts of drought in mustard by maintaining ROS homeostasis.

In situ decomposition of crop residues using lignocellulolytic microbial consortia: a viable alternative to residue burning.

Open field burning of crop residue causes severe air pollution and greenhouse gas emission contributing to global warming. In order to seek an alternative, the current study was initiated to explore the prospective of lignocellulolytic microbes to expedite in situ decomposition of crop residues. Field trials on farmers' field were conducted in the state of Haryana and Maharashtra, to target the burning of rice and wheat residue and sugarcane trash, respectively. A comparative study among crop residue removal (CRR), crop residue burning (CRB) and in situ decomposition of crop residues (IND) revealed that IND of rice and wheat residues took 30 days whereas IND of sugarcane trash took 45 days. The decomposition status was assessed by determining the initial and final lignin to cellulose ratio which increased significantly from 0.23 to 0.25, 0.21 to 0.23 and 0.24 to 0.27 for rice, wheat residues and sugarcane trash, respectively. No yield loss was noticed in IND for both rice-wheat system and sugarcane-based system; rather IND showed relatively better crop yield as well as soil health parameters than CRB and CRR. Furthermore, the environmental impact assessment of residue burning indicated a substantial loss of nutrients (28-31, 23-25 and 51-77 kg ha-1 of N+P2O5+K2O for rice, wheat and sugarcane residue) as well as the emission of pollutants to the atmosphere. However, more field trials, as well as refinement of the technology, are warranted to validate and establish the positive potential of in situ decomposition of crop residue to make it a successful solution against the crop residue burning.

Deciphering Cadmium (Cd) Tolerance in Newly Isolated Bacterial Strain, Ochrobactrum intermedium BB12, and Its Role in Alleviation of Cd Stress in Spinach Plant (Spinacia oleracea L.).

A cadmium (Cd)-tolerant bacterium Ochrobactrum intermedium BB12 was isolated from sewage waste collected from the municipal sewage dumping site of Bhopal, India. The bacterium showed multiple heavy metal tolerance ability and had the highest minimum inhibitory concentration of 150 mg L-1 of Cd. Growth kinetics, biosorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier transform infrared (FTIR) spectroscopy studies on BB12 in the presence of Cd suggested biosorption as primary mode of interaction. SEM and TEM studies revealed surface deposition of Cd. FTIR spectra indicated nitrogen atom in exopolysaccharides secreted by BB12 to be the main site for Cd attachment. The potential of BB12 to alleviate the impact of Cd toxicity in spinach plants (Spinacia oleracea L.) var. F1-MULAYAM grown in the soil containing Cd at 25, 50, and 75 mg kg-1 was evaluated. Without bacterial inoculation, plants showed delayed germination, decrease in the chlorophyll content, and stunted growth at 50 and 75 mg kg-1 Cd content. Bacterial inoculation, however, resulted in the early germination, increased chlorophyll, and increase in shoot (28.33%) and root fresh weight (72.60%) at 50 mg kg-1 of Cd concentration after 75 days of sowing. Due to bacterial inoculation, elevated proline accumulation and lowered down superoxide dismutase (SOD) enzyme activity was observed in the Cd-stressed plants. The isolate BB12 was capable of alleviating Cd from the soil by biosorption as evident from significant reduction in the uptake/translocation and bioaccumulation of Cd in bacteria itself and in the plant parts of treated spinach. Potential PGP prospects and heavy metal bioremediation capability of BB12 can make the environmental application of the organism a promising approach to reduce Cd toxicity in the crops grown in metal-contaminated soils.

Prevalence and Distribution of Selected Dental Anomalies in the Patients Reporting to Dental Institute, RIMS, Ranchi.

AIM: The purpose of this study was to determine the prevalence of developmental dental anomalies in the East Indian subpopulation. MATERIALS AND METHODS: The study was based on clinical examination, evaluation of dental casts, and radiographs of 2385 Indian patients (1169 males and 1216 females), who visited Dental Institute, Rajendra Institute of Medical Sciences, Ranchi. These patients were examined for shape anomalies, number anomalies, structural anomalies, and positional anomalies. RESULTS: It was observed that 5.83% of patients reported with a dental anomaly. Males reported with higher incidence with a male-to-female ratio of 1: 0.96. Microdontia was the most common anomaly. Unilateral microdontia was more common than bilateral and was more prominent in males (9.05%). It was observed that peg laterals were frequently encountered developmental anomaly at 1.34%, while the incidence of amelogenesis imperfecta and dentinogenesis imperfecta was 0.29% and 0.33%, respectively. The present demography reported a very low incidence of dens, fusion, hyperdontia, hypodontia, and macrodontia at <0.01%, whereas anomalies such as transportation, transmigration, and hypodontia of the maxillary molar reported no prevalence. CONCLUSION: The percentage of dental anomalies although low should be treated as soon as possible to avoid further complications. The results of our study can serve as an indicator to ascertain the pattern of dental anomalies in Jharkhand. This might help to plan the dental treatment of the community.

Cholic-Acid-Derived Amphiphiles Can Prevent and Degrade Fungal Biofilms.

Infections caused by fungal species via their existence as biofilms on medical devices can cause organ damage via candidiasis and candidemia. Different Candida species like Candida albicans can pose a serious threat by resisting host's immune system and by developing drug resistance against existing antimycotic agents. Therefore, targeting of fungal membranes can be used as an alternative strategy to combat the fungal infections. Here, we present screening of different amphiphiles based on cholic acid against different Candida strains as these amphiphiles can act as potent membrane-targeting antimycotic agents. Structure-activity correlations, biochemical assays and electron microscopy studies showed that amphiphiles having 4 and 6 carbon chains are most potent, safe and can act on the fungal membranes. Candida albicans did not show emergence of drug resistance on repeated usage of these amphiphiles unlike fluconazole. We show that these amphiphiles can prevent the formation of biofilms and also have the ability to degrade preformed biofilms on different substrates including acrylic teeth. We further demonstrate that amphiphiles 4 and 6 can clear the Candida albicans wound infections and prevent the biofilm formation on indwelling devices in murine models. Therefore, amphiphiles derived from cholic acid and their coatings provide suitable alternatives for inhibiting the fungal infections.

Polydopamine-on-liposomes: stable nanoformulations, uniform coatings and superior antifouling performance.

Polydopamine (PDA), a mussel-inspired synthetic polymer, affords biocompatible and antifouling coatings on a variety of surfaces. However, the traditional protocol of preparing PDA by polymerizing dopamine (DA) under basic conditions yields physically-unstable and non-uniform coatings that are prone to delamination and exhibit compromised antifouling performance in vivo. Here, we show that the high local pH in the vicinity of vesicular self-assemblies formed by a series of acetal-based cationic amphiphiles can be exploited to conveniently polymerise DA under physiological conditions in a gradual manner without requiring any external oxidant. Two of the four PDA-liposome nanoformulations viz. PDA-L1 and PDA-L2 turned out to be highly stable physically and resisted precipitation for more than a month while the other two formulations (PDA-L3 and PDA-L4) were less stable and formed visible precipitates with time. Further, the PDA-liposome formulations had significantly improved haemocompatibility compared to that of pristine liposomes. PDA-L1 formed highly uniform, nanostructured coatings on implants like catheter, cotton and bandages that did not delaminate even after a week of continuous incubation in simulated body fluid, or on exposure to pH change and presence of proteolytic enzymes. The PDA-L1 coated catheter implants resisted biofouling by both Gram-positive and Gram-negative bacteria in vitro and also had superior in vivo performance in mice vis-à-vis the implants coated with traditional base-polymerised PDA formulation (BP-PDA). Thus, these novel liposomal PDA nanoformulations significantly improve the practical utility of PDA-based coatings for antimicrobial applications.

In Vitro evaluation of remineralization potential of novamin on artificially induced carious lesions in primary teeth using scanning electron microscope and vickers hardness.

AIMS: The objective of this in vitro study was to find out the efficacy of Novamin in remineralizing enamel surface on which artificial caries lesion had been created. The changes were analyzed using Vickers Hardness Testing Machine and Scanning electron microscope (SEM). SETTINGS AND DESIGN: A total of 40 primary teeth were selected and divided into two groups: Control group and SHY NM (Novamin). All the samples were subjected to ph cycle protocol and assessed using Vickers Hardness Testing Machine and Scanning electron microscope. Each demineralized sample was randomly divided into two groups: Gp I -Control group, Gp II - Novamin (SHY NM). After 10-day period of ph cycle, the obtained data was analyzed statistically. STATISTICAL ANALYSIS USED: Pre and post groups were compared by paired t test. The significance of mean difference between the groups was done by Tukey's post hoc test after ascertaining normality by Shapiro-Wilk (W) test and homogeneity of variance by Levene's test. A two-tailed P value less than 0.05 (P < 0.05) was considered statistically significant. All analyses were performed on SPSS software (Windows version 17.0). RESULTS: Statistical analysis showed that bioactive glass (novamin) remineralizes artificially induced carious lesion in primary teeth. CONCLUSIONS: SHY NM (Novamin) exhibited superior remineralization potential.

Antioxidant, physiological and biochemical responses of drought susceptible and drought tolerant mustard (Brassica juncea L) genotypes to rhizobacterial inoculation under water deficit stress.

Response of drought susceptible (DS) genotype Pusa Karishma LES-39 and drought tolerant (DT) mustard genotype NPJ-124, to rhizobacterial inoculation under water deficit stress, was compared in the present study to determine the influence of inoculants on biochemical and physiological attributes of these two different genotypes. Inoculation was observed to improve root and shoot dry weight in both the genotypes, although better results were observed in the DS genotype. There was variation in the response of the two genotypes to rhizobacterial inoculation, under water deficit stress. Significant improvement in most of the physiological and biochemical parameters including antioxidative enzyme activities of the DS genotype; with concomitant decrease in starch content, accumulation of H2O2 and lipid peroxidation upon inoculation of rhizobacteria was observed. In contrast, there was improvement in only few physiological and biochemical parameters in the DT genotype in response to inoculation with rhizobacteria. There was significant increase in catalase enzyme activity along with concomitant decrease in lipid peroxidation. Thus, drought susceptibility of the mustard genotypes, NPJ-124 and Pusa Karishma LES-39, determined their physiological, biochemical and antioxidative responses to rhizobacterial inoculation under water deficit stress. Expression of drought stress responsive genes belonging to ABA-dependent (RD20 and RD26) and ABA-independent (DREB2 and DREB1-2) pathways was studied in the DS genotype. Expression of DREB2 and DREB1-2 genes was considerably enhanced due to inoculation under water deficit stress; indicating that in Bacillus-mediated priming for drought stress tolerance, in this genotype, ABA-independent pathway probably played key role in enhancing tolerance to drought stress.

Cholic Acid-Peptide Conjugates as Potent Antimicrobials against Interkingdom Polymicrobial Biofilms.

Interkingdom polymicrobial biofilms formed by Gram-positive Staphylococcus aureus and Candida albicans pose serious threats of chronic systemic infections due to the absence of any common therapeutic target for their elimination. Herein, we present the structure-activity relationship (SAR) of membrane-targeting cholic acid-peptide conjugates (CAPs) against Gram-positive bacterial and fungal strains. Structure-activity investigations validated by mechanistic studies revealed that valine-glycine dipeptide-derived CAP 3 was the most effective broad-spectrum antimicrobial against S. aureus and C. albicans CAP 3 was able to degrade the preformed single-species and polymicrobial biofilms formed by S. aureus and C. albicans, and CAP 3-coated materials prevented the formation of biofilms. Murine wound and catheter infection models further confirmed the equally potent bactericidal and fungicidal effect of CAP 3 against bacterial, fungal, and polymicrobial infections. Taken together, these results demonstrate that CAPs, as potential broad-spectrum antimicrobials, can effectively clear the frequently encountered polymicrobial infections and can be fine-tuned further for future applications.

Cholic Acid-Derived Amphiphile which Combats Gram-Positive Bacteria-Mediated Infections via Disintegration of Lipid Clusters.

Inappropriate and uncontrolled use of antibiotics results in the emergence of antibiotic resistance, thereby threatening the present clinical regimens to treat infectious diseases. Therefore, new antimicrobial agents that can prevent bacteria from developing drug resistance are urgently needed. Selective disruption of bacterial membranes is the most effective strategy for combating microbial infections as accumulation of genetic mutations will not allow for the emergence of drug resistance against these antimicrobials. In this work, we tested cholic acid (CA) derived amphiphiles tethered with different alkyl chains for their ability to combat Gram-positive bacterial infections. In-depth biophysical and biomolecular simulation studies suggested that the amphiphile with a hexyl chain (6) executes more effective interactions with Gram-positive bacterial membranes as compared to other hydrophobic counterparts. Amphiphile 6 is effective against multidrug resistant Gram-positive bacterial strains as well and does not allow the adherence of S. aureus on amphiphile 6 coated catheters implanted in mice. Further, treatment of wound infections with amphiphile 6 clears the bacterial infections. Therefore, the current study presents strategic guidelines in design and development of CA-derived membrane-targeting antimicrobials for Gram-positive bacterial infections.

Probing the Mechanism for Bipolar Resistive Switching in Annealed Graphene Oxide Thin Films.

The bipolar resistive switching (BRS) between a metallic low resistance state (LRS) and an insulating high resistance state (HRS) is demonstrated for annealed graphene oxide (GO) thin film-based device structures with aluminum (Al) as one of the contact electrodes. An optimal switching of ∼104 order is recorded for Al/GO (200 °C)/indium tin oxide (ITO) among the device structures in metal (M2)/GO (T)/metal (M1) configurations (M1 = Al, Au, or ITO and M2 = Au or Al), fabricated using GO (T)/metal (M1), annealed at different temperatures, T = 100, 200, 300, and 400 °C. The initial Ohmic conduction for electronic transport and the presence of metal contents through GO thin films in the X-ray photoelectron spectroscopy support the physical evidence of Al filament formation between the two electrodes as imaged by the high-resolution transmission electron microscopy. The speculated mechanism for BRS in repeated voltage sweep cycles is attributed to the current triggered breaking of metal filaments because of the combined effect of Joule's heating and Peltier heat generation at LRS → HRS transition, and electric field induced migration of metal atoms, leading to the formation of metal filaments through the GO film at the HRS → LRS transition. The higher switching ratio exhibited in the current study could be translated to engineer simple and low-cost resistive memory devices.

Performance Comparison of Systemic Inflammatory Response Syndrome with Logistic Regression Models to Predict Sepsis in Neonates.

In 2005, an international pediatric sepsis consensus conference defined systemic inflammatory response syndrome (SIRS) for children <18 years of age, but excluded premature infants. In 2012, Hofer et al. investigated the predictive power of SIRS for term neonates. In this paper, we examined the accuracy of SIRS in predicting sepsis in neonates, irrespective of their gestational age (i.e., pre-term, term, and post-term). We also created two prediction models, named Model A and Model B, using binary logistic regression. Both models performed better than SIRS. We also developed an android application so that physicians can easily use Model A and Model B in real-world scenarios. The sensitivity, specificity, positive likelihood ratio (PLR) and negative likelihood ratio (NLR) in cases of SIRS were 16.15%, 95.53%, 3.61, and 0.88, respectively, whereas they were 29.17%, 97.82%, 13.36, and 0.72, respectively, in the case of Model A, and 31.25%, 97.30%, 11.56, and 0.71, respectively, in the case of Model B. All models were significant with p < 0.001.

Phylloplane bacteria of Jatropha curcas: diversity, metabolic characteristics, and growth-promoting attributes towards vigor of maize seedling.

The complex role of phylloplane microorganisms is less understood than that of rhizospheric microorganisms in lieu of their pivotal role in plant's sustainability. This experiment aims to study the diversity of the culturable phylloplane bacteria of Jatropha curcas and evaluate their growth-promoting activities towards maize seedling vigor. Heterotrophic bacteria were isolated from the phylloplane of J. curcas and their 16S rRNA genes were sequenced. Sequences of the 16S rRNA gene were very similar to those of species belonging to the classes Bacillales (50%), Gammaproteobacteria (21.8%), Betaproteobacteria (15.6%), and Alphaproteobacteria (12.5%). The phylloplane bacteria preferred to utilize alcohol rather than monosaccharides and polysaccharides as a carbon source. Isolates exhibited ACC (1-aminocyclopropane-1-carboxylic acid) deaminase, phosphatase, potassium solubilization, and indole acetic acid (IAA) production activities. The phosphate-solubilizing capacity (mg of PO4 solubilized by 108 cells) varied from 0.04 to 0.21. The IAA production potential (µg IAA produced by 108 cells in 48 h) of the isolates varied from 0.41 to 9.29. Inoculation of the isolates to maize seed significantly increased shoot and root lengths of maize seedlings. A linear regression model of the plant-growth-promoting activities significantly correlated (p < 0.01) with the growth parameters. Similarly, a correspondence analysis categorized ACC deaminase and IAA production as the major factors contributing 41% and 13.8% variation, respectively, to the growth of maize seedlings.

Induction of osmoadaptive mechanisms and modulation of cellular physiology help Bacillus licheniformis strain SSA 61 adapt to salt stress.

Bacillus licheniformis strain SSA 61, originally isolated from Sambhar salt lake, was observed to grow even in the presence of 25 % salt stress. Osmoadaptive mechanisms of this halotolerant B. licheniformis strain SSA 61, for long-term survival and growth under salt stress, were determined. Proline was the preferentially accumulated compatible osmolyte. There was also increased accumulation of antioxidants ascorbic acid and glutathione. Among the different antioxidative enzymes assayed, superoxide dismutase played the most crucial role in defense against salt-induced stress in the organism. Adaptation to stress by the organism involved modulation of cellular physiology at various levels. There was enhanced expression of known proteins playing essential roles in stress adaptation, such as chaperones DnaK and GroEL, and general stress protein YfkM and polynucleotide phosphorylase/polyadenylase. Proteins involved in amino acid biosynthetic pathway, ribosome structure, and peptide elongation were also overexpressed. Salt stress-induced modulation of expression of enzymes involved in carbon metabolism was observed. There was up-regulation of a number of enzymes involved in generation of NADH and NADPH, indicating increased cellular demand for both energy and reducing power.

Degradation of sulphonated azo dye Red HE7B by Bacillus sp. and elucidation of degradative pathways.

Bacteria capable of degrading the sulfonated azo dye Red HE7B were isolated from textile mill effluent contaminated soil. The most efficient isolate was identified as Bacillus sp. Azo1 and the isolate could successfully decolorize up to 89% of the dye. The decolorized cultural extract analyzed by HPLC confirmed degradation. Enzymatic analysis showed twofold and fourfold increase in the activity of azoreductase and laccase enzymes, respectively, indicating involvement of both reductive and oxidative enzymes in biodegradation of Red HE7B. Degraded products which were identified by GC/MS analysis included various metabolites like 8-nitroso 1-naphthol, 2-diazonium naphthalene. Mono azo dye intermediate was initially generated from the parent molecule. This mono azo dye was further degraded by the organism, into additional products, depending on the site of cleavage of R-N=N-R molecule. Based on the degradation products identified, three different pathways have been proposed. The mechanism of degradation in two of these pathways is different from that of the previously reported pathway for azo dye degradation. This is the first report of a microbial isolate following multiple pathways for azo dye degradation. Azo dye Red HE7B was observed to be phytotoxic, leading to decrease in root development, shoot length and seedling fresh weight. However, after biotreatment the resulting degradation products were non-phytotoxic.