Isolation and Characterization of Thermophilic Bacteria from Gavmesh Goli Hot Spring in Sabalan Geothermal Field,Iran: Thermomonas hydrothermalis and Bacillus altitudinis Isolates as a Potential Source of Thermostable Protease

Abstract

Thermophilic bacteria have attracted great attention due to their ability to produce thermostable enzymes. The aim of this study was the isolation and characterization of thermophilic bacteria from Gavmesh Goli hot spring in Sareyn, North West of Iran. Of 10 water samples collected, 36 thermophilic bacteria were obtained. The thermophilic bacteria were tested for their ability to produce hydrolase enzymes. All the isolates were potentially protease producers. Lipase, DNase, and amylase activities were confirmed in 34 (94.4%), 8 (22.2%), and 3 (8.3%) isolates, respectively. Five isolates with higher levels of enzyme activity were selected for further studies. Morphological, biochemical, and molecular analysis by 16S rRNA gene sequencing revealed that four isolates (DH15, DH16, DH20, and DH29) could be identified as Thermomonas hydrothermalis and one (PA10) Bacillus altitudinis. The protease produced by these isolates was optimally active at 50–55?°C, pH 8–8.5, and 0–0.5?M NaCl. In this first time study, we isolated T. hydrothermalis and B. altitudinis from Iranian hot springs and demonstrated the characteristics of T. hydrothermalis protease. Accordingly, due to the valuable potential of these bacteria such as the production of protease with high temperature and pH stability, these isolates can be introduced as promising candidates for industrial applications.     

Growth of mixed cultures ofParacoccus denitrificans andDesulfovibrio desulfuricans in homogeneous and in heterogeneous culture systems

Obligate aerobes and anaerobes coexist closely in natural ecosystems. One species representative of each class (Desulfovibrio desulfuricans andParacoccus denitrificans) were selected for investigation in different laboratory growth systems. When incubated together, the aerobe protected the anaerobe against oxygen poisoning allowing the latter to grow and to reduce sulfate. When gas phase oxygen tension was systematically altered in stirred batch cultures, both species grew over a broad range of oxygen concentrations. Similar experiments in a chemostat indicated that conditions were far more exacting. No steady state was possible; however, at one critical oxygen tension the two species entered a stable oscillating cycle that lasted for 12 days. When the two organisms were grown in a gradostat in opposing gradients of sulfate plus oxygen and lactate, they coexisted but at different positions in the system. The actual position of the sulfate reducer was determined by the sulfate concentration in the reservoir.     

Temporal estimates of case-fatality rate for COVID-19 outbreaks in Canada and the United States

BACKGROUND:Estimates of the case-fatality rate (CFR) associated with coronavirus disease 2019 (COVID-19) vary widely in different population settings. We sought to estimate and compare the COVID-19 CFR in Canada and the United States while adjusting for 2 potential biases in crude CFR.METHODS:We used the daily incidence of confirmed COVID-19 cases and deaths in Canada and the US from Jan. 31 to Apr. 22, 2020. We applied a statistical method to minimize bias in the crude CFR by accounting for the survival interval as the lag time between disease onset and death, while considering reporting rates of COVID-19 cases less than 50% (95% confidence interval 10%–50%).RESULTS:Using data for confirmed cases in Canada, we estimated the crude CFR to be 4.9% on Apr. 22, 2020, and the adjusted CFR to be 5.5% (credible interval [CrI] 4.9%–6.4%). After we accounted for various reporting rates less than 50%, the adjusted CFR was estimated at 1.6% (CrI 0.7%–3.1%). The US crude CFR was estimated to be 5.4% on Apr. 20, 2020, with an adjusted CFR of 6.1% (CrI 5.4%–6.9%). With reporting rates of less than 50%, the adjusted CFR for the US was 1.78 (CrI 0.8%–3.6%).INTERPRETATION:Our estimates suggest that, if the reporting rate is less than 50%, the adjusted CFR of COVID-19 in Canada is likely to be less than 2%. The CFR estimates for the US were higher than those for Canada, but the adjusted CFR still remained below 2%. Quantification of case reporting can provide a more accurate measure of the virulence and disease burden of severe acute respiratory syndrome coronavirus 2.

The risk of death associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is fundamental to the disease burden imposed by the coronavirus disease 2019 (COVID-19) pandemic. Quantification of this risk can provide critical information on the health and socioeconomic impact of the pandemic and identify population subgroups at highest risk for severe outcomes. The risk of death from a diagnosed infection, often referred to as the case-fatality rate (CFR), is the proportion of people who die from a disease among all those diagnosed with the disease over a certain period.Estimates of the COVID-19 CFR vary in different populations and at different stages of the outbreak, ranging from 0.4% in China¹ to 31.4% in the northwest region of Italy.² From individual-level data for patients in Hubei Province, Mainland China,³ an adjusted CFR of 3.6% (95% confidence interval [CI] 3.6%–3.8%) was estimated. For the outbreak on the Diamond Princess cruise ship, the age-adjusted CFR was estimated at 2.6% (95% CI 0.9%–6.7%) in all age groups but was substantially higher (13.0%, 95% CI 5.2%–26.0%) among those aged 70 years or older.⁴For ongoing outbreaks and especially during the exponential growth phase, the delay between onset of disease and knowledge of the final outcome may result in biased estimates of the CFR.⁵ Furthermore, underestimation of the number of COVID-19 cases will inflate the CFR. Limited ability to test or recognize mildly or moderately symptomatic people in both the United States and Canada has likely led to substantial underestimation of the rate of infection in affected communities.^6,7Given the importance of the CFR in public health planning, we sought to estimate the CFR for ongoing COVID-19 outbreaks in the US and Canada while accounting for preferential ascertainment of severe cases (leading to underestimation) and the lag time between disease onset and death.     

Seasonal temperature as a factor influencing bacterial sulfate reduction in a saltmarsh sediment

The population of sulfate-reducing bacteria in saltmarsh sediment was examined at monthly intervals by plate-counting and by determining the response of sulfate reduction rates to environmental temperature using³⁵SO ₄ ^2– . The sulfate reduction rate was shown to be related to temperature by an Arrhenius function.The temperature characteristic of the population of sulfate-reducing bacteria did not vary significantly with season, and was shown to be equivalent to 20.4 kcals mole^–1, a Q₁₀ of 3.5. Apart from one anomolous result, the monthly value for the Arrhenius constant also did not show any significant variation throughout the year. There was no seasonal trend of optimum temperature for sulfate reduction.The results suggested that, although environmental temperature was the dominant variable influencing sulfate reduction rates in the sediment, there was no detectable response or adaptation of the sulfate-reducing population to seasonally changing environmental temperature.     

Improvement of inflammatory and toxic stress biomarkers by silymarin in a murine model of type one diabetes mellitus

Type 1 diabetes mellitus (T1DM) is characterized by an impairment of the insulin-secreting beta cells with an immunologic base. Inflammatory cytokines such as tumor necrosis factor (TNF)-α and interleukin (IL)-1β, and free radicals are believed to play key roles in destruction of pancreatic β cells. The present study was designed to investigate the effect of Silybum marianum seed extract (silymarin), a combination of several flavonolignans with immunomodulatory, anti-oxidant, and anti-inflammatory potential on streptozotocin (STZ)-induced T1DM in mouse. Experimental T1DM was induced in male albino mice by IV injection of multiplelow- doses of STZ for 5 days. Seventy-two male mice in separate groups received various doses of silymarin (20, 40, and 80 mg/kg) concomitant or after induction of diabetes for 21 days. Blood glucose and pancreatic biomarkers of inflammation and toxic stress (IL-1β, TNF-α, myeloperoxidase, lipid peroxidation, protein oxidation, thiol molecules, and total antioxidant capacity) were determined. Silymarin treatment reduced levels of inflammatory cytokines such as TNF-α and IL-1β and oxidative stress mediators like myeloperoxidase activity, lipid peroxidation, carbonyl and thiol content of pancreatic tissue in an almost dose dependent manner. No marked difference between the prevention of T1DM and the reversion of this disease by silymarin was found. Use of silymarin seems to be helpful in T1DM when used as pretreatment or treatment. Benefit of silymarin in human T1DM remains to be elucidated by clinical trials.     

Reactions of six cultivars of rice (Oryza sativa L.) to three fungal diseases

Abstract

Fungal diseases are the most important threat for rice production in the world. Rice fields were visited and sampled from diseased bushes to identify fungal diseases in Kohgiluyeh and Boyer-Ahmad province, in the south-west of Iran. Fungi were isolated from diseased tissues by Agar-plate method, and purified by single-spore or hyphal-tip methods. They were identified by studying morphological characteristics. The virulence of isolated fungi was evaluated on six dominant rice cultivars, Champa of temperate region, Champa of subtropical region, Gerdeh, Shamim, Fajr and Tarom, under greenhouse conditions. The experiment was set up in a factorial experiment in completely randomized design with four replicates. The incidence of three fungal diseases: brown spot caused by Curvularia australiensis and Bipolaris cookei, foot rot caused by Fusarium globosum and Fusarium sambucinum, and black root rot caused by Exserohilum pedicellatum, was proven in this study. Although, all of the tested cultivars significantly showed different reaction to these fungi, but the cultivars Champa of subtropical region and Tarom were resistant to foot rot as well as the black root rot and the cultivar Gerdeh was resistant to brown spot disease.     

Genetic Diversity of Selected Iranian Quinces Using SSRs from Apples and Pears

An Iranian National Quince collection containing 40 quince genotypes, originating from six distinct geographic areas, was screened using 15 SSR markers developed originally for apple and pear genomes. Overall, 13 markers exhibited polymorphism, with an average of 5.36 putative alleles per locus and a mean PIC value of 0.76. An UPGMA analysis divided the quince genotypes into five major clusters. The same results were obtained when the principal coordinates were plotted. The assignment test successfully allocated 83% of individuals into their place of origin. These results agree somewhat with the geographic origin of the quince accessions, and we conclude that geographic isolation leads to considerable genetic differentiation among Iranian quince collections. A significant ratio of transferability with a mean of 87.86% was measured, and we deduced that STMS markers derived from pear and apple have enough potential to detect polymorphism and differentiation in quince.     

Benefit of nicorandil using an immunologic murine model of experimental colitis

Inflammatory bowel disease (IBD) is a chronic inflammatory condition with an unknown etiology. Nicorandil, a potassium channel opener, has been used for many years for the treatment of angina. Recently, it has been shown that nicorandil possesses some novel traits such as anti-apoptotic, gastroprotective, free radical scavenging, and anti-inflammatory properties. Therefore, we set out to examine the possible beneficial effect of nicorandil in a rat model of IBD. Colitis was induced by rectal administration of 2,4,6-trintrobenzene sulphonic acid (TNBS) into rats. Groups of animals used in this study were sham, control, and exposure to dexamethasone, nicorandil, glibenclamid (a pure adenosine triphosphate sensitive potassium channel (KATP) blocker), or nicorandil plus glibenclamid. Drugs were administered by gavage and animals were sacrificed after 7 days. Biochemical markers, including TNF-α and IL-1β, ferric reducing/antioxidant power (FRAP), myeloperoxidase (MPO) activity and thiobarbitoric acid-reactive substance (TBARS), were measured in the homogenate of colonic tissue. Results indicate that nicorandil significantly reduces macroscopic and histological damage induced by TNBS. Nicorandil diminishes MPO activity and levels of TBARS, TNF-∢, and IL-1β in damaged colonic tissue with a concomitant increase in FRAP value (P<0.01). These effects were not reversed by coadministration of glibenclamide. In conclusion, nicorandil is able to ameliorate experimental IBD with a dose in which it does not show any anti-hypertensive effect, and the mechanism of which is partially or totally independent from KATP channels. It is hypothesized that nitric oxide donation and free-radical scavenging properties of nicorandil upregulate endothelial nitric oxide synthase may be responsible for this phenomenon. These findings suggest that nicorandil can be useful in treatment of IBD, although further investigations are needed to elucidate the mechanisms involved.