Phototrophic cultivation of NaCl‐tolerant mutant of Spirulina platensis for enhanced C‐phycocyanin production under optimized culture conditions and its dynamic modeling

Commercial cultivation of Spirulina sp. is highly popular due to the presence of high amount of C‐phycocyanin (C‐PC ) and other valuable chemicals like carotenoids and γ‐linolenic acid. In this study, the pH and the concentrations of nitrogen and carbon source were manipulated to achieve improved cell growth and C‐PC production in NaCl‐tolerant mutant of Spirulina platensis . In this study, highest C‐PC (147 mg · L^?1) and biomass (2.83 g · L^?1) production was achieved when a NaCl‐tolerant mutant of S. platensis was cultivated in a nitrate and bicarbonate sufficient medium (40 and 60 mM, respectively) at pH 9.0 under phototrophic conditions. Kinetic study of wildtype S. platensis and its NaCl‐tolerant mutant was also done to determine optimum nitrate concentrations for maximum growth and C‐PC production. Kinetic parameter of inhibition (Haldane model) was fitted to the relationship between specific growth rate and substrate concentration obtained from the growth curves. Results showed that the maximum specific growth rate (μ_max) for NaCl‐tolerant mutant increased by 17.94% as compared to its wildtype counterpart, with a slight increase in half‐saturation constant (K_s), indicating that this strain could grow well at high concentration of NaNO₃. C‐PC production rate (C_max) in mutant cells increased by 12.2% at almost half the value of K_s as compared to its wildtype counterpart. Moreover, the inhibition constant (K_i) value was 207.85% higher in NaCl‐tolerant mutant as compared to its wildtype strain, suggesting its ability to produce C‐PC even at high concentrations of NaNO₃.     

Melioration in Anti-staphylococcal Activity of Conventional Antibiotic(s) by Organic Acids Present in the Cell Free Supernatant of <Emphasis Type="Italic">Lactobacillus paraplantarum</Emphasis>

In view of emerging drug resistance in pathogens, there is a need to explore alternative strategies to combat infections. Use of probiotics is one such option. In this regard, efficacy of Lactobacillus plantarum has been reported against Staphylococcus aureus. Here, we propose that cell free supernatant (CFS) of Lactobacillus paraplantarum when used in combination with conventional antibiotics viz. ampicillin and oxacillin [to which the methicillin resistant Staphylococcus aureus (MRSA) strains were originally resistant] reduce the minimum inhibitory concentrations of these antibiotics, rendering the combination either synergistic or additive against the tested MRSA strain. The anti-staphylococcal activity was observed to be due to organic acids (acetic acid and lactic acid as confirmed by HPLC analysis) present in the CFS, as neutralization of the CFS with an alkali, sodium hydroxide (NaOH), caused the complete abrogation of its activity. The role of H₂O₂ and bacteriocin present in the CFS was also ruled out. The findings of this study suggest that cell free supernatant and ampicillin/oxacillin combination(s) might help in rejuvenating the use of conventional anti-staphylococcal antibiotics for the treatment of multi-drug resistant strains.     

Intra- and Intergenomic variation of Ploidy and Clonality characterize <Emphasis Type="Italic">Phytophthora capsici</Emphasis> on <Emphasis Type="Italic">Capsicum</Emphasis> sp. in Taiwan

Phytophthora capsici is a devastating disease of pepper (Capsicum sp.) in Taiwan causing complete loss of commercial fields. The objective of this study was to characterize genetic diversity for 38 newly collected isolates and three historical isolates. Analysis of data includes whole genome sequence for two new isolates and for two isolates collected previously in 1987 and 1995. In addition, 63 single nucleotide polymorphism loci were genotyped using targeted-sequencing, revealing 27 unique genotypes. Genotypes fell into three genetic groups: two of the groups contain 90% (n = 33) of the 2016 isolates, are triploid (or higher), are exclusively the A2 mating type and appear to be two distinct clonal lineages. The isolates from 2016 that grouped with the historical isolates are diploid and the A1 mating type. Whole genome sequence revealed that ploidy varies by linkage group, and it appears the A2 clonal lineages may have switched mating type due to increased ploidy. Most of the isolates were recently race-typed on a set of differential C. annuum, and although there was no direct correlation between virulence and ploidy, many of the triploid isolates were less virulent as compared to the historical diploid isolates. The implications for breeding resistant pepper and conducting population analyses are discussed.     

Enterococci in river Ganga surface waters: Propensity of species distribution, dissemination of antimicrobial-resistance and virulence-markers among species along landscape

Background  

Surface waters quality has declined in developing countries due to rapid industrialization and population growth. The microbiological quality of river Ganga, a life-sustaining surface water resource for large population of northern India, is adversely affected by several point and non-point sources of pollution. Further, untreated surface waters are consumed for drinking and various household tasks in India making the public vulnerable to water-borne diseases and outbreaks. Enterococci, the 'indicator' of water quality, correlates best with the incidence of gastrointestinal diseases as well as prevalence of other pathogenic microorganisms. Therefore, this study aims to determine the distribution of species diversity, dissemination of antimicrobial-resistance and virulence-markers in enterococci with respect to rural-urban landscape along river Ganga in northern India.     

An EPR study of the pH dependence of formate effects on Photosystem II.

Effects of formate on rates of O(2) evolution and electron paramagnetic resonance (EPR) signals were observed in the oxygen evolving PS II membranes as a function of pH. In formate treated PS II membranes, decrease in pH value resulted in the inhibition of the O(2) evolving activity, a decrease in the intensity of S(2) state multiline signal but an increase in the intensity of the Q(A)(-)Fe(2+) EPR signal. Time-resolved EPR study of the Y(Z)(*) decay kinetics showed that the light-induced intensity of Y(Z)(*) EPR signal was proportional to the formate concentration. The change in the pH affected both the light-induced intensities and the decay rates of Y(Z)(*), which was found to be faster at lower pH. At 253 K, t(1/e) value of Y(Z)(*) decay kinetics was found to be 8-10 s at pH 6.0 and 18-21 s at pH 5.0. The results presented here indicate that the extent of inhibition at the donor and the acceptor side of PS II due to formate is pH dependent, being more effective at lower pH.     

Chloroplasts and mitochondria have multiple heat tolerant isozymes of SOD and APX in leaf and inflorescence in Chenopodium album

Thermal stability of antioxidant defense enzymes superoxide dismutase (SOD, EC 1.15.1.1) and ascorbate peroxidase (APX, EC 1.11.1.11) was studied in chloroplasts and mitochondria of leaf and inflorescence in heat adaptive weed Chenopodium album. Leaf samples were taken in March (31 °C/14 °C) and young inflorescence (INF) was sampled at flowering in April (40 °C/21 °C). Leaf and INF chloroplast and mitochondrial fractions were subjected to elevated temperatures in vitro (5–100 °C) for 30′. SOD and APX showed activity even after boiling treatment in both chloroplast and mitochondria of leaf and INF. SOD was more heat stable than APX in both chloroplasts and mitochondria in both the tissues. Chloroplast contained more heat stable SOD and APX isozymes than mitochondria in both leaf and INF. To the best of our knowledge this is the first report showing presence of thermostable APX isozymes (100 °C for 30′) in chloroplasts and mitochondria in C. album. Heat stable isozymes of SOD and APX in chloroplasts and mitochondria in leaves and inflorescence may contribute to heat tolerance in C. album.     

Antagonists of anaphase-promoting complex (APC)-2-cell cycle and apoptosis regulatory protein (CARP)-1 interaction are novel regulators of cell growth and apoptosis

CARP-1/CCAR1, a perinuclear phosphoprotein, is a regulator of cell growth and apoptosis signaling. Although CARP-1 is a regulator of chemotherapy-dependent apoptosis, it is also a part of the NF-κB proteome and a co-activator of steroid/thyroid nuclear receptors as well as β-catenin signaling. Our yeast two-hybrid screen revealed CARP-1 binding with the anaphase-promoting complex/cyclosome E3 ubiquitin ligase component APC-2 protein. CARP-1 also binds with anaphase-promoting complex/cyclosome co-activators Cdc20 and Cdh1. Following mapping of the minimal epitopes involved in CARP-1 binding with APC-2, a fluorescence polarization assay was established that indicated a dissociation constant (K(d)) of 480 nm for CARP-1/APC-2 binding. Fluorescence polarization assay-based high throughput screening of a chemical library yielded several small molecule antagonists of CARP-1/APC-2 binding, termed CARP-1 functional mimetics. CFM-4 (1(2-chlorobenzyl)-5'-phenyl-3'H-spiro[indoline-3,2'-[1,3,4]thiadiazol]-2-one), a lead compound, binds with and stimulates CARP-1 expression. CFM-4 prevents CARP-1 binding with APC-2, causes G(2)M cell cycle arrest, and induces apoptosis with an IC(50) range of 10-15 μm. Apoptosis signaling by CFM-4 involves activation of caspase-8 and -9 and caspase-mediated ubiquitin-proteasome pathway-independent loss of cyclin B1 and Cdc20 proteins. Depletion of CARP-1, however, interferes with CFM-4-dependent cell growth inhibition, activation of caspases, and apoptosis. Because CFM-4 also suppresses growth of drug-resistant human breast cancer cells without affecting the growth of human breast epithelial MCF-10A cells, elevating CARP-1 by CFM-4 and consequent apoptosis could in principle be exploited to further elucidate, and perhaps effectively target, often deregulated cell cycle pathways in pathological conditions, including cancer.