Mechanisms of weak acid-induced stress tolerance in yeasts: Prospects for improved bioethanol production from lignocellulosic biomass

Weak acids are known to have a negative impact on yeast performance, restraining production efficiency during the production of bioethanol and other fermentative yeast-derived products. These acids, which might be hydrophilic or lipophilic exert negative effects on yeasts when they diffuse into the cell in their unionized state as a result of their pH being lower than the pka of yeast growth medium. Consequently, the unionized acids dissociate into their respective cations and anions, as intracellular pH is typically neutral. Further, proton accumulation tends to reduce intracellular pH. As a result, the anions destabilize the internal cell machinery, thus affecting cellular metabolism on various levels. Overcoming this acid-mediated stress in budding yeast would in part, harness the potential of using lignocellulosic biomass hydrolysate – which is typically acetic acid-rich – as a cheaper feedstock for large-scale bioethanol production. Since organic acids are key intermediates in ethanol fermentation, this review focuses on the prospects of bioethanol production from lignocellulosic biomass using weak acid-tolerant strains of yeasts derived by metabolic engineering.     

Synthesis of gold nanoparticles using Crinum macowanii bulb extracts and the application of these materials in blood detections at crime scenes

We here in report the synthesis of gold nanoparticles (AuNPs) using a Crinum macowanii bulb water extract. The as‐synthesized AuNPs were characterized using ultraviolet–visible spectroscopy, Fourier transform infrared spectroscopy, X‐ray diffraction, transmission electron microscopy, and a zeta potential‐sizer. The results showed that the as‐synthesized AuNPs were crystalline and mostly spherical in shape with a small mixture of triangular, tetrahedral, hexagonal, octagonal, and diamond shapes. The as‐synthesized AuNPs together with those synthesized by conventional methods were subsequently used as enhancers for the luminol signal in blood detection. It was noted that the AuNPs synthesized from the Crinum macowanii bulb water extract could enhance the chemiluminescence signal for blood detection by luminol to the same extent as AuNPs prepared by conventional methods. Furthermore, both types of AuNPs served as fluorescence enhancers for blood detection when luminol was replaced with the bulb water extract.     

An effective entomopathogenic fungus Metarhizium anisopliae for the simultaneous control of Aedes albopictus and Culex pipiens mosquito adults

The purpose of this study was to select the most effective Metarhizium anisopliae isolates for the simultaneous control of Aedes albopictus and Culex pipiens mosquito adults. The selection was performed using 65 isolates of M. anisopliae, an entomopathogenic fungus isolated from Korean soils. The selection process was carried out through evaluations of conidial thermotolerance, UV-B tolerance, pathogenicity and virulence against adults of two mosquito species and conidial production on grain medium. The thermotolerance of 65 M. anisopliae isolates ranged from 0% to 99%, and their UV-B tolerance ranged from 7.1% to 94.8%. Among them, 30 isolates with high thermotolerance were selected for evaluation of their pathogenicity and virulence against adults of the two mosquito species. Metarhizium anisopliae isolates were more susceptible to Cx. pipiens adults than Ae. albopictus adults because 11 isolates were pathogenic to Ae. albopictus and 21 isolates were pathogenic to Cx. pipiens. Virulence and conidial production were evaluated using 6 isolates with similar pathogenicity against the two species of mosquito. As a result, the accumulated mortality was 74–100% for Ae. albopictus and 78–100% for Cx. pipiens. LT₅₀ values ranged from 2.3 to 5.2 days for Ae. albopictus and from 3.2 − 4.7 days for Cx. pipiens. Comparison of conidial production using three kinds of grain media showed various results according to isolate and medium. Based on the above results, M. anisopliae CN6S1W1 was finally selected as the most effective fungal isolate for the simultaneous control of Ae. albopictus and Cx. pipiens mosquito adults.     

Metals and arsenic in marine fish commercialized in the NE Brazil: Risk to human health

Abstract

Arsenic, cadmium, lead, and mercury in fish is the result of long-term biomagnification in the food chain and is of public concern, due to the toxicity they engender. The objective of this research was to determine the concentrations of arsenic, cadmium, lead, and mercury in 13 species of marine fish broadly commercialized in Aracaju, SE, Brazil and to evaluate the risks of fish consumption associated with these trace elements, using the Target Hazard Quotient (THQ). As, Cd, and Pb levels were measured with inductively coupled plasma mass spectrometry (ICP-MS), and mercury was analyzed via cold vapor atomic absorption spectrometry. The results indicate a large variability in concentrations for arsenic (0.07–2.03?mg kg^–1) and mercury (0.01–1.44?mg kg^–1), associated with the animal dietary category. Cadmium (0.04–0.19?mg kg^–1) and lead (<0.01–0.45?mg kg^–1), on the other hand showed a mild variability. None of the evaluated specimens had As, Cd, and Pb THQ values higher than 1. The THQ values for mercury were higher but indicated no consumption risk, except for amberjack, and snook fish. Overall THQ indicates lower risk of consumption in fish that are at the base of the food chain, than in those that are top predators.     

A chromosome‐level genome assembly reveals the genetic basis of cold tolerance in a notorious rice insect pest,Chilo suppressalis

The rice stem borer, Chilo suppressalis, is one of the most damaging insect pests to rice production worldwide. Although C. suppressalis has been the focus of numerous studies examining cold tolerance and diapause, plant–insect interactions, pesticide targets and resistance, and the development of RNAi‐mediated pest management, the absence of a high‐quality genome has limited deeper insights. To address this limitation, we generated a draft C. suppressalis genome constructed from both Illumina and PacBio sequences. The assembled genome size was 824.35 Mb with a contig N₅₀ of 307 kb and a scaffold N₅₀ of 1.75 Mb. Hi‐C scaffolding assigned 99.2% of the bases to one of 29 chromosomes. Based on universal single‐copy orthologues (BUSCO), the draft genome assembly was estimated to be 97% complete and is predicted to encompass 15,653 protein‐coding genes. Cold tolerance is an extreme survival strategy found in animals. However, little is known regarding the genetic basis of the winter ecology of C. suppressalis. Here, we focused our orthologous analysis on those gene families associated with animal cold tolerance. Our finding provided the first genomic evidence revealing specific cold‐tolerant strategies in C. suppressalis, including those involved in glucose‐originated glycerol biosynthesis, triacylglycerol‐originated glycerol biosynthesis, fatty acid synthesis and trehalose transport‐intermediate cold tolerance. The high‐quality C. suppressalis genome provides a valuable resource for research into a broad range of areas in molecular ecology, and subsequently benefits developing modern pest control strategies.     

Anthropogenic noise reduces avian feeding efficiency and increases vigilance along an urban–rural gradient regardless of species’ tolerances to urbanisation

Anthropogenic noise can adversely impact urban bird populations by interfering with vocal communication. Less research has addressed if anthropogenic noise masks the adventitious sounds that birds use to aid predator detection, which may lead to increased vigilance and reduced feeding efficiency. We test this hypothesis using a controlled playback experiment along an urban–rural gradient in Sheffield (UK). We also test the related predictions that anthropogenic noise has the greatest impacts on vigilance and feeding efficiency in rural populations, and on species that are more sensitive to urbanisation. We focus on six passerines, in order from most to least urbanised (based on how urbanisation influences population densities): blue tit Cyanistes caeruleus, robin Erithacus rubeculla, great tit Parus major, chaffinch Fringilla coelebs, coal tit Periparus ater and nuthatch Sitta europaea. We used play-back of anthropogenic urban noise and a control treatment at 46 feeding stations located along the urban–rural gradient. We assess impacts on willingness to visit feeders, feeding and vigilance rates. Exposure to anthropogenic noise reduced visit rates to supplementary feeding stations, reduced feeding rates and increased vigilance. Birds at more urban sites exhibit less marked treatment induced reductions in feeding rates, suggesting that urban populations may be partially habituated or adapted to noisy environments. There was no evidence, however, that more urbanised species were less sensitive to the impacts of noise on any response variable. Our results support the adventitious sound masking hypothesis. Urban noise may thus interfere with the ability of birds to detect predators, reducing their willingness to use food rich environments and increase vigilance rates resulting in reduced feeding rates. These adverse impacts may compromise the quality of otherwise suitable foraging habitats in noisy urban areas. They are likely to be widespread as they arise in a range of species including common urban birds.