Synergistic influence of iodine and hydrogen peroxide towards the degradation of harmful algal bloom of Microcystis aeruginosa.

Cyanobacterial blooming due to the influence of temperature and increased nutrients in ponds/lakes aided by the runoff from agricultural lands, is a serious environmental issue. The presence of cyanotoxins in water may poison the health of aquatic organisms, animals, and humans. In this study, we focus on chemical assisted degradation of Microcystis aeruginosa- an alga that is of special relevance owing to its consistent blooming, especially in tropical regions. The study aims to ascertain the individual iodine (I) and hydrogen peroxide (H2O2) and their combination (hereinafter referred to as IH) effects on the degradation of Microcystis aeruginosa. As expected, the collected pond water revealed the presence of metal ions viz., Ni, Zn, Pb, Cu and Mn, which enriched the blooming of M. aeruginosa. Interestingly, a complete rupture of the cells - pigment loss, biochemical degradation and oxidative damage-was observed by the IH solution after exposure for ∼9 h under ambient conditions. In comparison to control (original water without chemicals), the addition IH completely eliminated the pigments phycocyanin (99.5%) and allophycocyanin (98%), and degraded ∼81% and 91% of carbohydrates and proteins, respectively due to the synergistic action of I and H. Superior degradation of algae through a simple and eco-friendly approach presented in this study could be explored more effectively towards its large-scale applicability.

Performance & clinical utility of oropharyngeal versus nasopharyngeal swabs in COVID-19.

Background & objectives: The oropharyngeal (OP) and nasopharyngeal (NP) swab samples are the most recommended clinical specimens for detecting SARS-CoV-2 in an individual through the quantitative real-time reverse-transcriptase-polymerase chain reaction (rRT-PCR) method. The primary objective of this study was to compare the performance of NP and OP swabs for the diagnosis of COVID-19 among 2250 concomitant samples (1125 NP + 1125 OP) using rRT-PCR test. Methods: This study was conducted at a tertiary care hospital in southern India. The study compared the specificity and efficacy of the two samples (NP & OP swabs) in 1125 individuals suspected having COVID-19 infection. The rRT-PCR values from all the samples were compared based on gender, age group and viral load. The differences between unmatched proportion and matched proportion were analysed. Agreement between the two methods was assessed using Kappa statistic. Absolute sensitivity, specificity, positive and negative predictive values (PPV and NPV) for OP and NP swabs were analysed. Results: The study identified a fair degree of agreement between OP and NP swabs in diagnosis of COVID-19 (kappa = 0.275, P <0.001). There was also a fair degree of agreement between NP and OP swabs irrespective of gender, age or duration of symptoms. NP swabs had better sensitivity and NPV as compared to OP swabs, however, specificity and PPV were 100 per cent for both. Interpretation & conclusions: The present study showed that both OP and NP swabs had similar sensitivity and specificity for predicting the presence of SARS-CoV-2.

Indole-3-butyric acid mediated growth and biochemical enhancement in three Selenastracean green microalgae under limited supply of nitrogen source.

The effects of Indole-3-butyric acid (IBA) supplementation in combination with nitrogen limitation on the biomass, biochemical and fatty acid composition of three selenastracean microalgae were studied. In the algae tested, nitrogen deficiency alone resulted in lower biomass output, whereas supplementation with 0.075 mM IBA resulted in increased biomass production on Selenastrum capricornutum (679 mg L-1), Ankistrodesmus falcatus (521 mg L-1) and Kirchneriella obesa (361 mg L-1) than their respective controls. The chlorophyll content of the algae showed a negative correlation with IBA dosage. Whilst it could significantly stimulate carotenoid biosynthesis in S. capricornutum and nitrogen limited (NL) alone, it influenced carotene production in both A. falcatus and K. obesa. Among the treatments, NL+ 0.075 mM IBA markedly increased the total lipid content to 1.2-fold in S. capricornutum, 0.81-fold in A. falcatus and 0.35-fold in K. obesa, with higher lipid productivity than control. NL+ 0.05 mM IBA significantly increased the amount of saturated fatty acids and NL+ 0.075 mM IBA significantly increased the amount of unsaturated fatty acids in all members of the Selenastraceae family under study. Thus, the study promises the importance of Selenastraceae members as a valuable feedstock for various process industries.

Phycoremediation resultant lipid production and antioxidant changes in green microalgae Chlorella Sp.

In this investigation, we report on the treatment of tannery wastewater using microalgae Chlorella species to produce lipid and fatty acid as well as changes in antioxidant metabolism during the treatment. The variation in growth, production of pigments, antioxidant metabolism, lipid and fatty acids, and nutrient removal from wastewater during the remediation were observed. Surprisingly, a profuse growth was found in 50% diluted tannery wastewater (TW), which supported to accumulate high yield of lipid (18.5%) and unsaturated fatty acids (50.05%). The antioxidant activity of microalgae in both the concentrations (50% and 100% TW) were viz., lipid peroxidation 1.6 ± 0.1 and 2.3 ± 0.02nmol MDA mg-1 protein, SOD 10.3 ± 0.4 and 15.7 ± 0.9 U mg-1 protein, CAT 0.17 ± 0.036 and 0.52 ± 0.06 U mg-1 protein, and APX 7.2 ± 0.8 and 11.2 ± 09 U mg-1 protein respectively, which point out that the free radical scavenging mechanism against heavy metal stress. Maximum phycoremediation of heavy metals observed from both concentrations during the healthy growth period were Cr - 73.1, 45.7%, Cu - 90.4, 78.1%, Pb - 92.1, 52.2%, and Zn - 81.2, 44.6%, respectively. This study proved the potential use of Chlorella for heavy metal and nutrient removal from tannery wastewater. Moreover, an unaffected growth with high antioxidant activity of this species promises a sustainable lipid and fatty acid contents for biofuel production.

Heavy metal induced antioxidant defense system of green microalgae and its effective role in phycoremediation of tannery effluent.

Investigation of tannery effluent toxicology in green microalgae is of great importance from ecological point of view, because heavy metal has become a major contaminant in recent years. The present study determined the effect of various concentrations (0, 10, 25, 50, 75 and 100%) of heavy metals containing tannery effluent on cell growth and antioxidant defense system of two green microalgae. Treatment with effluent induced accumulation of reactive oxygen species (ROS), superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX). Lower tannery effluent concentrations increased algal growth, whereas higher concentration suppressed the growth and photosynthetic content. Both strains of the microalgae had proven effective in removing heavy metals from aqueous solutions with the highest removal efficiency being near 100% and it can be used for phycoremediation of wastewater in large scale.

Growth and heavy metals accumulation potential of microalgae grown in sewage wastewater and petrochemical effluents.

Microalgae exhibit a number of heavy metal uptake process by different metabolism. In this study, the ability of microalgae for removal of heavy metal from wastewater was studied. Growth and biochemical contents of microalgae were determined by spectrophotometer. Heavy metal analysis of wastewater effluents were performed by atomic absorption spectrophotometer before and after treatment at laboratory scale. The growth of Scenedesmus bijuga and Oscillatoria quadripunctulata in sewage wastewater was higher than those grown in synthetic medium. Whereas, the growth of S. bijuga and O. quadripunctulata in sterilized petrochemical effluents was slightly lower than that grown in the standard synthetic medium. The chlorophyll, carotenoid and protein content of S. bijuga and O. quadripunctulata grown in sterilized sewage wastewater were higher than those grown in the standard medium. Similarly S. bijuga and O. quadripunctulata grown in sterilized petrochemical effluents showed lower contents of pigments and protein than those grown in sewage and synthetic medium. Heavy metals copper, cobalt, lead and zinc were removed by 37-50, 20.3-33.3, 34.6-100 and 32.1-100%, respectively from sewage wastewater and petrochemical effluent using Ocillatoria culture. The metal absorption by S. bijuga were (Cu, Co, Pb, Zn) 60-50, 29.6-66, 15.4-25 and 42.9-50%, respectively from sewage and petrochemical effluents. Both species showed high level of heavy metal removal efficiency and metal sorption efficiency of both microalgae depended on the type of biosorbent, the physiological status of the cells, availability of heavy metal, concentration of heavy metal and chemical composition of wastewater.