Effective voltammetric tool for Nano-detection of triazine herbicide (1-Chloro-3-ethylamino-5-isopropylamino-2,4,6-triazine) by naphthalene derivative.

The development and operation of a nanosensor for detecting the poisonous 1-chloro-3-ethylamino-5-isopropylamino-2,4,6-triazine (Atrazine) are described in this study for the first time. The carbon electrode (CE) surface was modified with cysteine-substituted naphthalene diimide to create this sensitive platform. The developed nanosensor (NDI-cys/GCE) was evaluated for its ability to sense Atrazine using differential pulse voltammetry and cyclic voltammetry. To achieve the best response from the target analyte, the effects of several parameters were examined to optimize the conditions. The cysteine-substituted naphthalene diimide significantly improved the signals of the Atrazine compared to bare GCE due to the synergistic activity of substituted naphthalene diimide and cysteine molecules. Under optimal conditions, atrazine detection limits at the (NDI-cys/GCE) were reported to be 94 nM with a linear range of 10-100 µM. The developed sensing platform also showed positive results when used to detect the atrazine herbicide in real tap water, wastewater, and milk samples. Furthermore, a reasonable recovery rate for real-time studies, repeatability, and stability revealed that the developed electrochemical platform could be used for sample analysis.

Applicability of new sustainable and efficient green metal-based nanoparticles for removal of Cr(VI): Adsorption anti-microbial, and DFT studies.

Artemisia absinthium leaves were utilized as a reducing agent for green synthesis of Zinc oxide nanoparticles (particle size 17 nm). Synthesized green-ZnO (g-ZnO) were characterized by SEM/EDX, FTIR, XRD, UV, and BET analyses and then further used as an adsorbent to remove Cr(VI) ions from simulated wastewater. Optimal pH, temperature and adsorbent dosage were determined through batch mode studies. High removal efficiency and adsorption capacity were observed at pH 4, 0.25 g L-1 dosage, and 25 mg L-1 concentration of Cr(VI). Experimental data were modelled with different adsorption kinetics (Elovich model, PFO, PSO, IDP model) and isotherms (Langmuir, Freundlich, and Temkin), and it was found the adsorption process was well fitted to Langmuir with an R2 value greater than>0.99. Computational calculation showed that the g-ZnO nanoparticles became ∼14 times more dynamic with delocalized surface states making them a relevant platform to adsorb Cr with greater work function compatibility supporting the experimental findings. The Qmax adsorption capacity of g-ZnO was 315.46 mg g-1 from Langmuir calculations. Thermodynamic calculations reveal that the Cr (VI) adsorption process was spontaneous and endothermic, with a positive ΔS value representing the disorder at the solid-solution interface during the adsorption. In addition, the present study has demonstrated that these g-ZnO nanoparticles show strong antibacterial activities against P. aeruginosa (MTCC 1688) and E. coli (MTCC 1687). Also, the novel g-ZnO adsorbent capacity to remove Cr(VI) from simulated water revealed that it could be reused at least six times with higher removal rates during regeneration experiments. The results obtained from adsorption and antimicrobial activities suggest that g-ZnO nanoparticles could be used effectively in real-time wastewater and agricultural safety applications.

Removal of Pb ions using green Co3O4 nanoparticles: Simulation, modeling, adsorption, and biological studies.

Chemical co-precipitation synthesized novel and green cobalt-oxide nanoparticles (Co3O4-NPs) utilizing cobalt nitrate as cobalt precursors. FTIR, Raman, scanning electron microscopy, UV visible, X-ray powder diffraction, and BET was used to analyze the surface characteristics, composition, and morphology, of the NPs. These green Co3O4-NPs were employed to remove Pb ions from simulated wastewater solutions at various pH, adsorbate, temperature, and dose concentrations. At dose 20 mg/L, pH 6.0, 20 mg/L (Pb(II) solution, 25 °C of temperature, and 45 min for equilibrium, nearly 99.44% of Pb ions were removed. To evaluate the kinetic data, four different kinetic equations were used. The data fit the Elovich rate equation better than the other three models. Thermodynamic and isothermal studies were also evaluated, and the maximum adsorption capacity of 450.45 mg/g was observed at 298.15 K. 0.1 M HNO3, and 0.1 HCl were used to regenerate used Co3O4-NPs. Simulation results show the strong correlation of the Co atom in the Co3O4-NPs generates active delocalized surface states, which are energetically most favorable for heavy metal (Pb ions) adsorption and removal, supporting the experimental outcomes. In concluding remarks, green Co3O4-NPs can also be used as an adsorbent to remove Pb ions from wastewater bodies.

Recoding anaerobic regulator fnr of Salmonella Typhimurium attenuates it's pathogenicity.

AIMS: How recoding of fnr, an anaerobic regulatory gene, affects pathogenicity related parameters of Salmonella Typhimurium (STM). METHODS AND RESULTS: The fnr gene was recoded by substituting all of it's codons with synonymous rare codons of STM. Recoding fnr gene severely reduced the ability of the recoded mutant to compete with wild strain under nutrient depletion condition. Mutants were also less motile than the wild strain and their biofilm forming ability was significantly decreased as compared to wild strain. The recoded strain showed significant reduced survival within murine macrophages (RAW264.7) and monocyte derived macrophage of poultry origin. The colonisation ability of recoded mutant in liver and spleen of mice on day 5 of post infection was significantly reduced. The recoded strain exhibited significant reduction in faecal shedding on day 1 and 5 after infection. CONCLUSIONS: Our study showed that recoding the anaerobic regulator fnr of STM significantly compromised its growth, decreased motility, biofilm forming ability and survival within macrophages. Further, the recoded fnr strain showed reduced colonisation ability and faecal shedding in mice. Thus, these findings highlight that recoding the global anaerobic regulator fnr of Salmonella Typhimurium attenuates its pathogenicity.

Evaluation of spatial spreading of phyto-available sulphur and micronutrients in cultivated coastal soils.

Understanding the spatial spreading patterns of plant-available sulphur (S) (AS) and plant-available micronutrients (available zinc (AZn), available iron (AFe), available copper (ACu), available manganese (AMn) and available boron (AB)) in soils, especially in coastal agricultural soils subjected to various natural and anthropogenic activities, is vital for sustainable crop production by adopting site-specific nutrient management (SSNM) strategies. We studied the spatial distribution patterns of AS, AZn, AFe, ACu, AMn, and AB in cultivated soils of coastal districts of India using geostatistical approaches. Altogether 39,097 soil samples from surface (0 to 15 cm depth) layers were gathered from farm lands of 68 coastal districts. The analysis of soil samples was carried out for soil pH, electrical conductivity (EC), soil organic carbon (SOC) and AS, AZn, AFe, ACu, AMn, and AB. Soil pH, EC and SOC varied from 3.70 to 9.90, 0.01 to 7.45 dS m-1 and 0.02 to 3.74%, respectively. The concentrations of AS, AZn, AFe, ACu, AMn, and AB varied widely in the study area with their corresponding mean values were 37.4±29.4, 1.50±1.53, 27.9±35.1, 2.14±1.74, 16.9±18.4 and 1.34±1.52 mg kg-1, respectively. The coefficient of variation values of analyzed soil parameters varied from 14.6 to 126%. The concentrations of AS, AZn, AFe, ACu, AMn, and AB were negatively and significantly correlated with soil pH and positively and significantly correlated with SOC. The geostatistical analysis indicated stable, Gaussian and exponential best-fit semivariogram models with moderate to strong spatial dependence for available nutrients. The generated spatial spreading maps revealed different distribution patterns for AS, AZn, AFe, ACu, AMn, and AB. There were variations in spatial spreading patterns of AS, AZn, AFe, ACu, AMn, and AB in east- and west-coastal area. About 62, 35, 12, 0.4, 23 and 45% of the study area had deficiency of AS, AZn, AFe, ACu, AMn, and AB, respectively. The spatial spreading maps will be highly useful for SSNM in the cultivated coastal soils of the country. This study could also be used as a base for assessing spatial spreading patterns of soil parameters in cultivated coastal areas of other parts of the world.

Evaluation of the diagnostic potential and DIVA capability of recombinant LigBCon1-5 protein of Leptospira interrogans serovar Pomona in canine leptospirosis.

BACKGROUND: Canine leptospirosis is a serious public health concern. AIMS: This study aims to investigate the feasibility of conserved first to fifth domains of recombinant Leptospira immunoglobulin like protein B antigen (rLigBCon1-5) as a serodiagnostic marker for detecting canine leptospirosis. METHODS: A total of 340 unvaccinated canine serum samples were screened using microscopic agglutination test (MAT) and rLigBCon1-5 based immunoglobulin G (IgG) indirect-enzyme-linked immunosorbent assay (I-ELISA). Further, 60 vaccinated canine sera were screened using MAT and rLigBCon1-5 based latex agglutination test (LAT). RESULTS: Microscopic agglutination test results revealed seropositivity of 28.6%. The relative sensitivity, specificity, and accuracy of IgG I-ELISA in comparison to MAT were 100%, 96.0%, and 97.2%, respectively. Out of 60 vaccinated sera, 46 sera reacted with MAT alone, and eight sera reacted by both tests, while six sera were non-reactive with both tests. Anti-LigB antibodies were detected in eight canine sera by rLigBCon1-5 based LAT. In five LAT reactive sera, agglutinins of locally circulating Leptospira serovars Grippotyphosa (n=4) and Australis (n=1) were detected. In three LAT reactive sera, agglutinins against Icterohaemorrhagiae (n=3) produced due to natural infection were present. CONCLUSION: Immunoglobulin G based indirect ELISA assay (IgG I-ELISA) can be employed as an alternative test instead of MAT. rLigBCon1-5 based LAT detected anti-LigB antibodies in eight vaccinated sera where the vaccine failure occurred partially or totally due to the limited efficacy spectrum of Nobivac® RL and cold chain breakage. This vaccine could not provide cross-protection against locally circulating Leptospira serovars. The recombinant LigBCon1-5 antigen based LAT possesses capability of differentiating infected from vaccinated individuals (DIVA capability) when employed as a pen-side test for detecting canine leptospirosis.

District-level epidemiology, hot spots and sociodemographic determinants of tobacco use in Indian men and women: analysis of national family health survey-4 (2015-16).

OBJECTIVES: To map district-level tobacco hot spots and understand the Sociodemographic Indices (SDI) influencing tobacco consumption in Indian men and women. STUDY DESIGN: Cross-sectional study. METHODS: Tobacco use data from 640 districts of India were extracted from National Family Health Survey-4, carried out from 2015 to 2016 with a sample size of 103,411 men and 699,686 women. Geographic Information System was used to map the tobacco prevalence, and hot spots were identified by spatial statistics (Getis-OrdGi∗). SDI were studied by bivariate analyses and binary logistic regression. RESULTS: India has two major tobacco hot spots; one comprising the districts of North-Eastern states, excluding Sikkim, and the second cluster is formed by the districts of Central-Eastern states. These hot spots coincide well with demographic determinants: North-East (adjusted odds ratio [aOR] men, 5.74; aOR women, 13.54) and Central India (aOR men, 4.5; aOR women, 3.5) have higher odds of Tobacco consumption. In men, respondents with no education (aOR 2.52; 95% confidence interval [CI]: 2.26-2.81) and Muslims (aOR 3.53; 95% CI: 2.93-4.26) have higher odds of tobacco consumption. The poorest (men aOR, 2.06; 95% CI: 1.87-2.27; women aOR, 3.36: 95% CI: 2.69-4.19) and ST women (aOR 1.89; 95% CI: 1.68-2.13) have higher odds of tobacco consumption. CONCLUSIONS: We have identified tobacco hot spots and detailed the SDI affecting tobacco use separately in men and women to guide public health policies for targeted intervention of tobacco consumption.

Pre-monsoon spatial distribution of available micronutrients and sulphur in surface soils and their management zones in Indian Indo-Gangetic Plain.

The efficient (site-specific) management of soil nutrients is possible by understanding the spatial variability in distribution of phyto-available nutrients (here after called available nutrients) and identifying the soil management zones (MZs) of agricultural landscapes. There is need for delineating soil MZs of agricultural landscapes of the world for efficient management of soil nutrients in order to obtain sustainability in crop yield. The present study was, therefore, undertaken to understand the spatial distribution pattern of available micronutrients (zinc (Zn), boron (B), iron (Fe), manganese (Mn) and copper (Cu)), available sulphur (S), and soil properties (soil acidity (pH), electrical conductivity (EC) and organic carbon (SOC) content) in soils of intensively cultivated Indo-Gangetic Plain (IGP) of India and to delineate soil MZs for efficient management of soil nutrients. Totally, 55101 soil samples from 0-15 cm depth were obtained from 167 districts of IGP during 2014 to 2017 and were analysed for different soil parameters. Soil pH, EC and SOC content varied from 4.44 to 9.80, 0.02 to 2.13 dS m-1 and 0.10 to 1.99%, respectively. The concentration of available Zn, B, Fe, Mn, Cu and S varied from 0.01 to 3.27, 0.01 to 3.51, 0.19 to 55.7, 0.05 to 49.0, 0.01 to 5.29 and 1.01 to 108 mg kg-1, respectively. Geostatistical analysis resulted in varied distribution pattern of studied soil parameters with moderate to strong spatial dependence. The extent (% area) of nutrient deficiencies in IGP followed the order: S > Zn > B > Mn > Cu > Fe. Principal component analysis and fuzzy c-means clustering produced six distinctly different soil MZs of IGP for implementation of zone-specific soil nutrient management strategies for attaining sustainability in crop yield. The developed MZ maps could also be utilized for prioritization and rationalization of nutrients supply in IGP of India.

An unusual case of Cheyletiellosis in a Persian cat and its therapeutic management.

A male Persian cat was presented with a history of alopecia at the dorsal tail region, with mild pruritus, flaking of skin and the owner's complaint of pruritus on herself and her family members. All the vital signs of the cat were found within the normal reference range. Skin scraping and hair samples were found to be negative for Demodex spp. and Sarcoptes spp. of mites, pediculosis and fungal infestation. Physical examination of the whole body revealed absence of fleas or flea eggs. Further, food hypersensitivity was ruled out by gradually changing the previous wheat based diet to a commercial cat food. However, eggs of Cheyletiella spp. were seen on microscopic examination of skin scraping and the lesions on the owner's body were indicative of infestation by Cheyletiella spp. as it's zoonotic in nature. A treatment protocol was initiated that included Ivermectin and bath with a shampoo containing selenium sulphide. Owners were advised to apply Calamine lotion on their lesions. Both the owner and patient recovered uneventfully 3 months post-therapy.

Prospective evaluation of the diagnostic potential of LipL32 based latex agglutination test for Bovine leptospirosis.

The Livestock Sector of India plays an important role in livelihood security and socioeconomic development of rural households. Leptospirosis is an important zoonotic disease responsible for septicaemia, interstitial nephritis, jaundice, abortion, reproductive problem in most of the animal species. Reproductive disturbances in bovine population is most often restricted to investigation of brucellosis, however apart from brucellosis, there are many undiagnosed diseases like leptospirosis that takes a toll in the reproductive anomalies of cattle and buffalo. Hence, the present study was elucidated to screen the seroprevalence of Leptospira in cattle and buffalo in various hamlets of North India using a user friendly screening test i.e. LipL32 latex agglutination test. The overall seropositivity was found to be 26.01% (230/884) in case of bovine in this study and the LipL32 LAT showed a profound sensitivity and specificity with level of 94.97% and 99.53% respectively.

Prospective evaluation of the diagnostic potential of LipL32 based latex agglutination test for Bovine leptospirosis

@#The Livestock Sector of India plays an important role in livelihood security and socioeconomic development of rural households. Leptospirosis is an important zoonotic disease responsible for septicaemia, interstitial nephritis, jaundice, abortion, reproductive problem in most of the animal species. Reproductive disturbances in bovine population is most often restricted to investigation of brucellosis, however apart from brucellosis, there are many undiagnosed diseases like leptospirosis that takes a toll in the reproductive anomalies of cattle and buffalo. Hence, the present study was elucidated to screen the seroprevalence of Leptospira in cattle and buffalo in various hamlets of North India using a user friendly screening test i.e. LipL32 latex agglutination test. The overall seropositivity was found to be 26.01% (230/884) in case of bovine in this study and the LipL32 LAT showed a profound sensitivity and specificity with level of 94.97% and 99.53% respectively.

Retraction Note to: Therapeutic management of trypanosomosis with ophthalmic involvement in a dog.

[This retracts the article DOI: 10.1007/s12639-017-0953-z.].

Therapeutic management of trypanosomosis with ophthalmic involvement in a dog.

The present report communicates a case of canine trypanosomosis with ophthalmic involvement, its diagnosis, hemato-biochemistry and therapeutic management in a 2 year old dog. The dog had history of bilateral corneal opacity and impaired vision since last 4 weeks. On the basis of history and clinical signs, a presumptive diagnosis of canine trypanosomosis was made followed by confirmation with Giemsa stained buffy coat smear examination. Therapeutic regimen was comprised of Diminazine aceturate @ 3.5 mg/kg deep IM for two occasions 24 h apart along with parenteral fluids, hematinics, NSAID and multivitamins which yielded favourable response by third day post-therapy. Haemato-biochemical parameters took nearly 14 days of time to return to near normal levels. Improvement with respect to corneal opacity took 6 weeks of time and the animal was followed up to 3 months without any recurrence.

Prevalence of gastrointestinal parasites in bovines in and around Junagadh (Gujarat).

Coprological examination of 416 bovine faecal samples revealed the presence of parasitic stages of Toxocara vitulorum, strongyles, Strongyloides spp., Fasciola spp., amphistomes, coccidia (Eimeria spp. and Cryptosporidium spp.) and Buxtonella sulcata. About 42 % (n = 302) faecal samples from cattle and 36 % (n = 114) samples from buffaloes were positive for gastrointestinal (GI) parasitic infections. Both cattle (14.57 %) and buffalo (15.79 %) had the highest incidence of Buxtonella sulcata, respectively. The overall incidence of GI parasitic infections in young animals (below 1 year) was higher followed by older (more than 5 years) and adult animals (1-5 years) and the difference was statistically significant (p < 0.05). Non descriptive breeds of bovines showed more parasitic infections than pure breeds, the difference being statistically non-significant (p > 0.05). Season wise GI parasitic infections were recorded to be non-significantly (p > 0.05) higher in monsoon (48.38 %) followed by summer (39 %) and winter (34.61 %) in cattle. There was no significant variation of GI infections in buffaloes in relation to season though highest prevalence was documented in monsoon (44.89 %) followed by winter (35.71 %) and summer (24.32 %). Similarly, sex wise females recorded higher infection rates than males in bovines and the difference being statistically non-significant (p > 0.05).

Theileriasis in crossbred cows and its therapeutic management: first report from Lushai hill district of Mizoram.

To know the prevalence of theileriosis infection, haemato-biochemical alteration and efficacy of Oxytetracycline in combination with Diaminazene aceturate injection against theileriosis in Lushai hill district of Mizoram; fifty five cross bred cattle were screened during July, 2013 to November, 2013. The prevalence of tropical theileriosis was 9.09 % based on blood smear examination. Clinical features of the disease were manifested by high rise of body temperature 104.8 ± 1.2 °F, lymphadenopathy, inability to walk, anorexia, listlessness, moderate anaemia, nasal discharge, edema of eye and corneal opacity. There were marked decline (P < 0.01) in the haemoglobin 5.28 ± 1.81 gm/dl, total erythrocytic count 2.14 ± 0.7 × 10(6)/ul, packed cell volume 18.10 ± 0.8 % and total leukocyte count 6.95 ± 1.05 × 10(3)/ul, respectively. Erythrocyte sedimentation rate was significantly increased (P < 0.01) up to 104.5 ± 12.4 mm/1st hour. The percentage of neutrophils increased 62.75 ± 2.77 and lymphocytes decreased drastically 28.69 ± 1.45 as compared with un-infected cross bred cattle. Clinically infected cattle with Theileria annulata had significantly low levels of total proteins and albumin, (P < 0.05) but AST, total, direct and indirect bilirubin, BUN, creatinine levels and Ck-MB activity were significantly high (P < 0.05). Oxytetracycline in combination with Diaminazene aceturate was found effective against T. annulata and could control fever and temperature returns to normalcy by 7th day post treatment along with some haemato-biochemical profiles. In brief, the study revealed that tropical theileriosis was prevalent in Lushai hill district of Mizoram especially among cross breed cattle and had effect on hepatic, renal and cardiac function which can be effectively controlled by Oxytetracycline and Diaminazene aceturate injection.

Study of Methaemoglobin in Malaria Patients.

To estimate the concentration of methemoglobin (MetHb) in malaria patients and correlate with severity of malaria infection. This prospective study included 30 untreated cases of malaria confirmed by Quantitative Buffy Coat (QBC) test and 30 age sex matched non-malarial cases taken as controls. All the patients underwent thorough clinical examination and routine biochemical investigation. Methemoglobin levels were estimated by spectrophotometric (co-oxymeter) method on day 1 and day 10 of diagnosis of all study group patients and correlated with clinical profile and severity. Out of 30 malaria patients 22 were males and eight were females. The clinical presentations in complicated malaria group (n = 21) were fever 21 (100 %), anemia 17 (80.95 %), renal failure 12 (52.38 %) and coma/convulsion 5 (23.8 %). The mean age of the study group was 41.66 years. Mean MetHb in complicated malaria on day 1 was 2.55 ± 1.75 % and day 10 was 10.69 ± 8.19 % (statistically significant). The overall mortality was 13 (43.33 %) among study group while 5 (16.66 %) was found among control group. Mean MetHb who died (n = 13) on day 1 was 3.144 ± 1.829 % and (n = 8) on day 10 it was 19.982 ± 8.406 %. Increase in level of methaemoglobin is detrimental to the body and is associated with increase in mortality. Routine MetHb estimation may be used as a prognostic indicator in the management of malaria patients. It is suggested that addition of drugs which reduce MetHb may be tried along with antimalarial drugs to decrease morbidity and mortality in malaria.

High Incidence of Zidovudine Induced Anaemia in HIV Infected Patients in Southern Odisha.

Zidovudine (AZT), a nucleoside reverse transcriptase inhibitor was the first breakthrough in AIDS therapy in 1990.This study was conducted with an aim to determine prevalence of AZT induced anaemia in HIV infected patients initiated on AZT containing anti retroviral therapy(ART) regimen and also to find out any risk factor for causing AZT induced anaemia. Study was carried out in ART centre, M.K.C.G, MCH, Berhampur between Jan 2009 and Dec 2011. HIV infected patients registered at ART centre were treated according to National AIDS Control Organisation (NACO) guidelines. Patients (n = 1221) with Hb >8 gm/dl were prescribed AZT based ART regimen. Patients having anaemia (<8 gm/dl) were excluded from the study. Correlation of baseline characteristics (age, sex, weight, Hb level, CD4 count, World Health Organization (WHO) clinical stage) with risk of developing anaemia was also calculated. 178 (14.6 %) patients on AZT regimen developed anaemia. Patients with low CD4 count were more prone to develop severe anaemia. Age, sex, weight, WHO clinical stage had no relation with development of anaemia. Incidence of AZT induced anaemia was very high and patients having low CD4 count were more susceptible to develop anaemia.

A report on pharmacognostical evaluation of four Adiantum species, Pteridophyta, for their authentication and quality control

Genus Adiantum L., Pteridaceae, is an important fern used in traditional systems of medicine. Different species of Adiantum are known as avenca in Brazil; hansraj/hanmspadi in India; maiden hair fern in English. The present study aims to develop the quality control parameters of four similar looking Adiantum species viz. A. capillus-veneris L., A. lunulatum Burm. f., A. peruvianum Klotzsch, and A. venustum D. Don. Standard methods for macro-microscopic evaluation, physico-chemical parameters and HPTLC were used for authentication and identification. The salient distinctive characters under the microscope are the presence of slightly wavy elongated epidermal cells in A. capillus-veneris; epidermal cells strongly wavy in A. lunulatum; star shaped epidermal cells and mixed spores of regular and irregular shaped in A. peruvianum; stomata on both the surfaces of pinnule, absence of spinulus spores only in A. venustum. In addition, rachis anatomy showed different cellular and stellar characteristics as identifying characters of aforesaid four Adiantum species. Physico-chemical parameters and HPTLC finger print profiles along with stigmasterol and lupeol play significant role for the quality evaluation of raw drugs. The above finding will serve the purpose of quality control and assurance for the future studies.

Extraction of nickel by microbial reduction of lateritic chromite overburden of Sukinda, India.

Microbial extraction of nickel from lateritic chromite overburden (COB), Sukinda by Acidithiobacillus ferrooxidans has been investigated in this work. In anoxic environment, A. ferrooxidans reduced the ferric iron in goethite [Fe(O)OH] mineral of COB by using elemental sulphur as electron donor. Nickel embedded in the complex goethite matrix of COB was successfully recovered by cumulative action of sulphuric acid, generated by oxidation of elemental sulphur and reduction of ferric iron in goethite matrix by A. ferrooxidans. Forty one percent of the nickel present in COB was extracted in a 3 L scale bioreactor (pH of 1.8 ± 0.05, temperature of 28 ± 2°C) maintained in anoxic environment. In contrast, only 11% of the nickel present in COB was extracted with continuous supply of air to the bioreactor keeping all the parameters unchanged. Kinetics study of anoxic microbial processing of COB revealed that the chemical reaction rate control model fits to the rate of nickel dissolution (R(2)=0.975).