Biologia最新文献

In this study, growth and enzyme production of Bacillus megaterium RB-05 was achieved at varying parameters such as temperature, incubation time, pH, carbon source and nitrogen source. Naturally occurring sand with 97% quartz was utilized as the matrix for bacterial growth and CaCO₃ precipitation. The estimation of CaCO₃ precipitation was done through gravimetric analysis and CaCO₃ deposition was detected through EDX and SEM analysis. Furthermore, sand stabilization was determined through Drained triaxial tests. The results obtained showed maximum bacterial growth and urease activity at pH 7, 35⁰C temperature and 48 h incubation time. Bacteria showed maximum growth with glucose as carbon source however, significant urease activity was observed with both glucose and maltose. Optimum bacterial growth was observed with ammonium chloride as the nitrogen source however, maximum urease activity was observed with ammonium sulphate. CaCO₃ precipitation of treated sand showed a linear relation between CaCO₃ precipitation with urease production. The EDX and SEM analysis showed CaCO₃ deposition between sand particles and on the surface. Furthermore, the stress response of sand showed enhanced sand strength at maximum CaCO₃ precipitation. The obtained results show the link between urease production, CaCO₃ precipitation, and sand stabilization by MICP. High urease activity influences CaCO₃ precipitation in the soil followed by enhanced soil strength. However, the positive results were obtained in reactor environment, further studies are required to make the technique applicable.

Polyphosphate (polyP) is an important energy and phosphate storage polymer present in all organisms. In Streptomyces, the deletion of the polyP kinase (PPK) gene resulted in an antibiotic-overproducing phenotype. However, the industrial use of overproducing ∆ppk Streptomyces strains is hampered by their increased sensitivity to oxidative stress, likely indicating an increase in their internal oxidative stress. Iron is an essential element for various cellular processes, yet excess iron generates oxidative stress, particularly via the Fenton reaction. Interestingly, polyP can sequester iron, reducing its bioavailability and thus oxidative stress. The aim of this study was to elucidate the relationships between polyP metabolism, iron homeostasis and oxidative stress in Streptomyces coelicolor. To achieve this, comparative proteomic analyses were conducted on three biological replicates of wild-type (WT) and ∆ppk strains grown in iron-containing and iron-free media. The results indicated that even in the absence of iron, the deletion of ppk significantly altered the total proteome, thereby confirming the importance of PPK in the cellular metabolism. For instance, proteins involved in energy metabolism and protein folding were more abundant in the ∆ppk mutant than in the WT. In the presence of iron the abundance of the proteins involved in phosphate metabolism, oxidative stress response, and translation was higher in the ∆ppk mutant strain than in the WT. To the best of our knowledge, this is the first study to elucidate the relationship between iron homeostasis, oxidative stress, and polyphosphate in Streptomyces.

The occurrence of Vibrio cholerae, Vibrio metschnikovii and Vibrio fluvialis, important aquatic human pathogens of genus Vibrio, were determined in the surface water of the Danube River in Bratislava. The isolates were identified by biochemical tests. Biochemical characteristics of environmental isolates could be slightly different from reference and clinical strains which is reflected in dissimilarity rate, which was in our case not sufficient. A molecular method called amplified ribosomal DNA restriction analysis was used for confirmation of phenotypic identification. The species identity of 19 out of 22 isolates was confirmed, in the case of 3 misidentified ones, the identity of the genus did not change. The identity of all V. cholerae isolates was confirmed by PCR using species-specific gene called ompW. Also, main virulence factors of these isolates were determined. None of the isolates possessed all three virulence factors necessary for the induction of cholera.

The present study tries to account for the diversity of desmids and also determine their distribution and abundance in Thattekkad Bird Sanctuary, situated in Ernakulam District, the first Bird Sanctuary in Kerala and lies within the geographical limits of 10°08′N 76°41′E and 10°13′N 76°68′E. The water samples collected were preserved and the physico-chemical parameters were analyzed using standard protocols. The study was carried out over a period of one year, from March 2022 to April 2023 in three seasons (pre-monsoon, monsoon, and post-monsoon) from the freshwater resources within the sanctuary like rivers, streams, and ponds. The following physico-chemical parameters of water were analyzed: the concentration of nitrates and phosphates, pH, temperature, dissolved oxygen (DO), biological oxygen demand (BOD), and turbidity. Desmids are unicellular algae that belong to conjugating green algae and occur exclusively in freshwaters, each cell consists of two almost symmetrical and often profusely sculptured segments. The current study identified a total of seventy-four taxa, which are distributed under four families and 18 genera. Predominant genera included were Cosmarium (21), Euastrum (12), and Staurastrum (8). Notably Heimansia pusilla, Euastrum praemorsum, Euastrum jenneri, Staurastrum saltans var. javanicum, Cosmarium clepsydra var. bicardia are new reports to India, five species are new reports to Kerala and all species being novel to Thattekkad Bird Sanctuary. The Shannon’s diversity index is in the range of 0.8070 to 1.0151, and Simpson’s Index range between 0.5051 to 0.6177.

The distribution and diversity of insects are crucial conservation issues. The order Trichoptera is comprised of numerous endangered species, but the rarity of some makes it challenging to determine their conservation priority. In recent decades, data based on caddisfly larvae have become more frequent in limnological research in Slovakia. Our research, focusing mainly on adult caddisflies, has led to more reliable and accurate identification of many species that cannot be identified with certainty in the larval stage.We combined several entomological methods, including sweeping, Malaise traps, and UV light attraction, to increase the likelihood of catching rare species. The text lists and discusses the discoveries of caddisfly species that are particularly important for faunistics or biodiversity in Slovakia, as well as in the Central European context. Enoicyla reichenbachii (Kolenati, 1848), Limnephilus incisus Curtis, 1834, Ptilocolepus granulatus (Pictet, 1834) and Oecetis testacea (Curtis, 1834) were recorded for the first time in Slovakia. The rare species Hagenella clathrata (Kolenati, 1848) and Adicella balcanica Botosaneanu and Novák, 1965, previously found in Slovakia, were also recorded. Additionally, a new locality of Adicella syriaca Ulmer, 1907 indicates a further northward shift of this Mediterranean species. We further discussed the faunistically important records of Beraeamyia hrabei Mayer, 1937, Allotrichia pallicornis (Eaton, 1873), Ceraclea riparia (Albarda, 1874), Grammotaulius nitidus (Müller, 1764) and Limnephilus fuscicornis Rambur, 1842 from Slovakia. The conservation status of each species is proposed and discussed on the basis of our faunistic records, in accordance with the forthcoming update of the Slovak Red Book.

A neonicotinoid insecticide, imidacloprid (IMI), has been widely used by seed treatment to control the sucking and biting insects since the nineties. Although it has been regarded as a highly recalcitrant pesticide, with reports of half-lives in the soil of 174 days and its use was banned in several countries for use on several crops, there is a limited number of reports on its mycoremediation. Considering also the difficulties in the control of its illegal use in some countries, seventeen fungal strains were isolated and tested for their IMI removal capacity in the current study, and Acremonium sclerotigenum was selected for further experiments. This is the first report indicating the usability of this biomass material cultivated in the molasses medium for IMI removal. Effect of some parameters on bioremoval rate, such as pH (4, 5, 6, 7), pesticide concentration (2.6, 6.7, 18.3, 33.9 and 44.0 mg/L), incubation time (48, 96 and 144 h), and amount of inoculum were tested. The maximum specific IMI uptake was obtained as 15.4 mg/g at 33.9 mg/L IMI concentration. The highest bioremoval rates observed for 2.6 and 6.7 mg/L pesticide levels were 100% at the end of 48 h at pH 6. The fungus could also remove 8.9% of 44.0 mg/L IMI at 96 h. This study suggests that A. sclerotigenum holds the potential for effective removal of IMI from the affected environment.

Immuno-compromised COVID-19 patients being treated with glucocorticoids like Dexamethasone for prolonged periods had led to the surge of mucormycosis. Mucor spores proliferate and spread faster in COVID afflicted persons. In India, more than 51,775 cases and 4300 deaths due to COVID-associated mucormycosis were reported till date. The Government of J&K declared an epidemic of COVID-19 associated mucormycosis under Sect. 2 of the Epidemic Disease Act, 1897. In the backdrop of current COVID scenario, it becomes imperative to study the etiological factors, occurrence of causative agents and aerosolisation of the Mucor spores from the environmental samples leading to mucormycosis. The present study was undertaken to check the presence of Mucor spores in the environment so as to find the reinforcing sources of COVID associated mucormycosis. We isolated three strains of Mucor species: Mucor circinelloides and two Mucor hiemalis species, from environmental samples (air, soil and water), all having a positive relevance to mucormycosis. This is the first study on the presence of mucormycosis causing Mucor species in Kashmir environment. In this study, some pathogenicity marker tests were performed to detect the virulence of these fungal strains such as Anti-fungal susceptibility test (AST), biofilm formation and heat stress test. The in vitro antifungal susceptibility of these species showed the major zone of inhibition by Amphotericin B (Amph) and Nystatin (NS), whereas, Fluconazole (FLC) showed no activity. Biofilm was formed by both Mucor species which was confirmed by crystal violet assay (CV) with positive absorbance readings in microplate reader. Under heat stress, pathogenicity marker test was performed in which both species formed considerable aseptate hyphal growth and small scattered spores. During SEM (Scanning Electron Microscopy) analysis, both the species of Mucor were observed with intact sporangia producing several sporangiospores, whose size dimorphism is linked to its virulence. Thus, augmented knowledge of the epidemiology and clinical presentations of these Mucor species may prevent environmental exposure of immune-compromised patients post-COVID and improve early diagnosis and treatment.

Using chemical insecticides remains the main way to prevent and manage dengue and malaria, two main mosquito-borne diseases. However, the vectors of these diseases have developed resistance to chemical insecticides. Essential oils (EOs) could be used as alternatives because besides their larvicidal and adulticidal properties, they have repellent properties. In Burkina Faso, studies on the repellent properties of essential oils on mosquitoes remained limited. The EOs extracted from five plants (Cymbopogon citratus, Cymbopogon nardus, Eucalyptus camaldulensis, Lippia multiflora, and Ocimum americanum) collected in Ouagadougou were tested on populations of Aedes aegypti and Anopheles gambiae s.l collected in Bobo-Dioulasso and the Kou of Valley, respectively. Susceptible strains of the two species were also tested. DEET and permethrin were used as positive controls. Most of the 5 EOs tested produced irritant effects on adults of Aedes aegypti and Anopheles gambiae. The irritant effects on mosquito adults were significantly influenced by the concentration of the EOs and species of mosquitoes. On Anopheles gambiae s.l, the repellent-irritant effects of Cymbopogon citratus, Cymbopogon nardus, and Eucalyptus camaldulensis EOs were very close to DEET. On Aedes aegypti, all our EOs had higher repellent-irritant effects and some of them were very close to DEET. EOs could be used as alternative repellents to pyrethroids in vector control.