As organisms adaptively evolve to a new environment, selection results in the improvement of certain traits, bringing about an increase in fitness. Trade-offs may result from this process if function in other traits is reduced in alternative environments either by the adaptive mutations themselves or by the accumulation of neutral mutations elsewhere in the genome. Though the cost of adaptation has long been a fundamental premise in evolutionary biology, the existence of and molecular basis for trade-offs in alternative environments are not well-established. Here, we show that yeast evolved under aerobic glucose limitation show surprisingly few trade-offs when cultured in other carbon-limited environments, under either aerobic or anaerobic conditions. However, while adaptive clones consistently outperform their common ancestor under carbon limiting conditions, in some cases they perform less well than their ancestor in aerobic, carbon-rich environments, indicating that trade-offs can appear when resources are non-limiting. To more deeply understand how adaptation to one condition affects performance in others, we determined steady-state transcript abundance of adaptive clones grown under diverse conditions and performed whole-genome sequencing to identify mutations that distinguish them from one another and from their common ancestor. We identified mutations in genes involved in glucose sensing, signaling, and transport, which, when considered in the context of the expression data, help explain their adaptation to carbon poor environments. However, different sets of mutations in each independently evolved clone indicate that multiple mutational paths lead to the adaptive phenotype. We conclude that yeasts that evolve high fitness under one resource-limiting condition also become more fit under other resource-limiting conditions, but may pay a fitness cost when those same resources are abundant. Microorganisms such as yeast have been used for decades to study adaptive evolution by natural selection. Thirty years ago in now seminal experiments, a strain of yeast was evolved multiple times under carbon limitation. The adaptive changes that gave rise to increases in fitness have previously been studied both phenomenologically and mechanistically but not in detail at the molecular level. To better understand the basis for these strains' fitness increase, we sequenced their genomes and identified putative adaptive mutations. We found that multiple mutational paths lead to these fitness increases. We also determined whether the evolved yeasts' gains in fitness under the original conditions in some cases diminished fitness under other conditions. We therefore evaluated their performance relative to the ancestral strain under the evolutionary and two alternative resource-limiting conditions by determining the ancestral and evolved strains' relative fitnesses and gene-expression levels under all three conditions. We found scant evidence among evolved strains for fitness trade-offs when nutrients were scarce, but discovered a cost was paid when nutrients were plentiful.

In the present study, the syntheses of crystalline silver and gold nanoparticles (NPs) has been demonstrated in a green and environmentally friendly approach using citrus fruit extracts (lemon, Citrus limon (Cl-1) and sweet orange, Citrus limetta (Cl-2)). In addition, potentially hazardous metal ion sensing properties of these NPs in aqueous solution has been explored. Cl-1 and Cl-2 that predominantly contained citric and ascorbic acid, exhibited different reducing abilities towards silver and gold ions into NPs. Cl-1 reduces silver ions into AgNPs only in the presence of sunlight whereas AuNPs from gold ions were formed without exposure to sunlight. In contrast, Cl-2 converts both silver and gold ions into the corresponding NPs in the absence of sunlight. The colorimetric sensor studies of these green synthesized AgNPs (Cl-1–AgNPs) showed selective sensing of the potentially hazardous Hg²⁺ ion in water at micromolar concentrations. More importantly, green synthesized Cl-1–AgNPs sensor systems detected Hg²⁺ ions in water in a wide pH range (3.2 to 8.5).

We explored whether copper nanoparticles (CuNPs) can function as an efflux pump inhibitor and as an anti-biofilm agent. Our results showed that at 0.5× (0.065 mM) Minimum Inhibitory Concentration (MIC), CuNPs exhibited remarkable efflux inhibitory effect in wild type strains of both Staphylococcus aureus and Pseudomonas aeruginosa and less but significant efflux inhibitory effect against MRSA and drug resistant mutant strains of Staphylococcus aureus. At 1× MIC (0.13 mM) concentration, they significantly inhibited monoculture biofilms formed by Staphylococcus aureus and Pseudomonas aeruginosa. Membrane permeability, membrane integrity and confocal imaging provided insight into the mechanism of the antibacterial effect of CuNPs. Efflux inhibition and antibacterial effect of CuNPs was partly mediated by particle effect and partly by ion effect. A novel efflux pump inhibitory role for CuNPs is reported in our study. Proof of concept experiments revealed that CuNPs could reverse the MIC of the mutant Staphylococci aureus strain for ciprofloxacin by 4 fold (from 64 μg ml⁻¹ to 16 μg ml⁻¹), hence our study reveals that CuNPs could be potentially employed as bacterial adjuvants to curtail Multi Drug Resistant (MDR) bacteria.

Fat-splitting enzymes (lipases), due to their natural, industrial, and medical relevance, attract enough attention as fats do in our lives. Starting from the paper that we write, cheese and oil that we consume, detergent that we use to remove oil stains, biodiesel that we use as transportation fuel, to the enantiopure drugs that we use in therapeutics, all these applications are facilitated directly or indirectly by lipases. Due to their uniqueness, versatility, and dexterity, decades of research work have been carried out on microbial lipases. The hunt for novel lipases and strategies to improve them continues unabated as evidenced by new families of microbial lipases that are still being discovered mostly by metagenomic approaches. A separate database for true lipases termed LIPABASE has been created recently which provides taxonomic, structural, biochemical information about true lipases from various species. The present review attempts to summarize new approaches that are employed in various aspects of microbial lipase research, viz., screening, isolation, production, purification, improvement by protein engineering, and surface display. Finally, novel applications facilitated by microbial lipases are also presented.

Background: Interspecific hybridization occurs in every eukaryotic kingdom. While hybrid progeny are frequently at a selective disadvantage, in some instances their increased genome size and complexity may result in greater stress resistance than their ancestors, which can be adaptively advantageous at the edges of their ancestors' ranges. While this phenomenon has been repeatedly documented in the field, the response of hybrid populations to long-term selection has not often been explored in the lab. To fill this knowledge gap we crossed the two most distantly related members of the Saccharomyces sensu stricto group, S. cerevisiae and S. uvarum, and established a mixed population of homoploid and aneuploid hybrids to study how different types of selection impact hybrid genome structure. Results: As temperature was raised incrementally from 31°C to 46.5°C over 500 generations of continuous culture, selection favored loss of the S. uvarum genome, although the kinetics of genome loss differed among independent replicates. Temperature-selected isolates exhibited greater inherent and induced thermal tolerance than parental species and founding hybrids, and also exhibited ethanol resistance. In contrast, as exogenous ethanol was increased from 0% to 14% over 500 generations of continuous culture, selection favored euploid S. cerevisiae x S. uvarum hybrids. Ethanol-selected isolates were more ethanol tolerant than S. uvarum and one of the founding hybrids, but did not exhibit resistance to temperature stress. Relative to parental and founding hybrids, temperature-selected strains showed heritable differences in cell wall structure in the forms of increased resistance to zymolyase digestion and Micafungin, which targets cell wall biosynthesis. Conclusions: This is the first study to show experimentally that the genomic fate of newly-formed interspecific hybrids depends on the type of selection they encounter during the course of evolution, underscoring the importance of the ecological theatre in determining the outcome of the evolutionary play.

Drug resistance is a serious concern in a clinical setting jeopardizing treatment for both infectious agents and cancers alike. The wide-spread emergence of multi-drug resistant (MDR) phenotypes from bacteria to cancerous cells necessitates the need to target resistance mechanisms and prevent the emergence of resistant mutants. Drug efflux seems to be one of the preferred approaches embraced by both microbial and mammalian cells alike, to thwart the action of chemotherapeutic agents thereby leading to a drug resistant phenotype. Relative to microbes, which predominantly employs proton motive force (PMF) powered, Major Facilitator Superfamily (MFS)/Resistance Nodulation and Division (RND) classes of efflux pumps to efflux drugs, cancerous cells preferentially use ATP fuelled ATP binding cassette (ABC) transporters to extrude chemotherapeutic agents. The prevalence, evolutionary characteristics and overlapping functions of ABC transporters have been highlighted in this review. Additionally, we outline the role of ABC pumps in conferring MDR phenotype to both bacteria and cancerous cells and underscore the importance of efflux pump inhibitors (EPI) to mitigate drug resistance. Based on the literature reports and analysis, we reason out feasibility of employing bacteria as a tool to screen for EPI’s targeting ABC pumps of cancerous cells.