Multivariate phenotypic divergence due to the fixation of beneficial mutations in experimentally evolved lineages of a filamentous fungus

The potential for evolutionary change is limited by the availability of genetic variation. Mutations are the ultimate source of new alleles, yet there have been few experimental investigations of the role of novel mutations in multivariate phenotypic evolution. Here, we evaluated the degree of multivariate phenotypic divergence observed in a long-term evolution experiment whereby replicate lineages of the filamentous fungus Aspergillus nidulans were derived from a single genotype and allowed to fix novel (beneficial) mutations while maintained at two different population sizes. We asked three fundamental questions regarding phenotypic divergence following approximately 800 generations of adaptation: (1) whether divergence was limited by mutational supply, (2) whether divergence proceeded in relatively many (few) multivariate directions, and (3) to what degree phenotypic divergence scaled with changes in fitness (i.e. adaptation). We found no evidence that mutational supply limited phenotypic divergence. Divergence also occurred in all possible phenotypic directions, implying that pleiotropy was either weak or sufficiently variable among new mutations so as not to constrain the direction of multivariate evolution. The degree of total phenotypic divergence from the common ancestor was positively correlated with the extent of adaptation. These results are discussed in the context of the evolution of complex phenotypes through the input of adaptive mutation

Microbial Community Structure of Three Traditional Zambian Fermented Products: Mabisi, Chibwantu and Munkoyo

Around the world, raw materials are converted into fermented food products through microbial and enzymatic activity. Products are typically produced using a process known as batch culture, where small volumes of an old culture are used to initiate a fresh culture. Repeated over many years, and provided samples are not shared among producers, batch culture techniques allow for the natural evolution of independent microbial ecosystems. While these products form an important part of the diets of many people because of their nutritional, organoleptic and food safety properties, for many traditional African fermented products the microbial communities responsible for fermentation are largely unknown. Here we describe the microbial composition of three traditional fermented non-alcoholic beverages that are widely consumed across Zambia: the milk based product Mabisi and the cereal based products Munkoyo and Chibwantu. Using culture and non-culture based techniques, we found that six to eight lactic acid bacteria predominate in all products. We then used this data to investigate in more detail the factors affecting community structure. We found that products made from similar raw materials do not harbor microbial communities that are more similar to each other than those made from different raw materials. We also found that samples from the same product taken at the same location were as different from each other in terms of microbial community structure and composition, as those from geographically very distant locations. These results suggest that microbial community structure in these products is neither a simple consequence of the raw materials used, nor the particular suite of microbes available in the environment but that anthropogenic variables (e. g., competition among sellers or organoleptic preferences by different tribes) are important in shaping the microbial community structures

Reducing fitness costs associated with antibiotic resistance: experimental evolution in the filamentous fungus Aspergillus nidulans

The 1990s saw the growth of two distinct strands of debates on the transformations and emerging problems besetting the urban space. One of these has focused on the relationship between globalisation and the similar changes metropolitan cities are undergoing, as they become home to numerous global economic agents such as multinational firms. According to it, globalisation can be understood as a worldwide reaching 'space of flows' - of money, information, and physical streams - emerging within a 'network society', and landing into the urban space triggering multiple cultural, political, economic, societal, and spatial transformations. In so doing, globalisation is prompting new challenges in dealing with urban management issues, once the 'space of flows' meets the 'space of place', that is, the physical contiguity of the urban node, govemed by the particularities of the city's regime, such as its political, cultural, and economic background.Developing in parallel, the other strand of debates has focused on the relationship between the natural and built environments, exploring the ecological footprint of buildings, their impacts on local infrastructures and new technologies that are emerging to curb them. Rather technocratic, this lint: ofthought describes buildings as one of the main environmental disrupters of modernity - accountable for elevated indexes of energy, water, and finite natural resources' use, and related ecological problems spanning from local infrastructure overburden, to global warming, ozone depletion, deforestation, desertification, and so on.Both strands of debates have been elucidating. On the other hand, they have also been incomplete. While demonstrating how globalisation has become a dominating key point for understanding contemporary urban change, the first line overlooks the urban environmental dimension, that is, how globalisation may trigger urban environmental challenges and/or may be a vehicle for introducing environmental management solutions. The other approach, while quantifying the environmental impacts of buildings in general and describing technical solutions to mitigate them, falls short when analysing the societal processes that are leading to, or hindering, an ecological upgrading of buildings - i.e., how such technological modernisation is or may be steered amid different social actors.This study aims at making a bridge between such two research lines by providing an environmental perspective to the global city research as well as a societal dimension to the sustainable building literature. As segments of the urban space have transnationalised with globalisation, with the presence of multinational firms and other global economic agents connecting key cities throughout the planet, the skyscraper has turned into a 'transnational building' . This is a local structure that not only rules the skyline of the global city, posing numerous local environmental burdens, but which is now also embedded in the global space of flows, subject to its regimes. This study analyses how the transnational building may become a sustainable building, canalising environmental innovations from the global space of flows into the urban space. By focusing on offices held by multinational firms in specific locations, it explores how and why such firms are - or are not promoting in-house environmental management practices, and whether they may form a worldwide virtuous circle leading to a global network of urban environmental change. Its aim is to understand how sustainable building practices are being activated .in certain urban nodes of the network society and may transcend to other urban nodes, and how the dynamics of urban environmental change at the interface between the space of flows (the environmental regimes of global companies) and the space of places (urban environmental and utility management policies) may vary in view of the different economic and political backgrounds of each city. How is the greening of transnational buildings developing in different urban settings? Which actors are pushing for, and which are hindering, such greening process?To deal with these questions, both theoretical perspectives as well as empirical research methods are used. Theory-wise, a central proposition organising the enquiry suggests that a new trend in environmental polities has emerged, in which the state 'retreats' from developing top-down environmental policies while marketfactors start to play a central role in triggering environmental change. While the state remains imperative as an environmental change 'enabler', the dynamics of environmental change is nevertheless implemented by market actors, following an ecological modernisation logic, in which the environment becomes a central criterion in production and consumption processes. Deriving from this, and in the tradition ecological modernisation studies, a central hypothesis this research puts forward is that, in the era of globalisation g/oba/ market actors may trigger urban environmental reforms, with multinational firms concentrating head offices in key cities while dispersing their activities throughout the planet. In this case, such firms may form a virtuous - as well as virtua/ - circle of worldwide urban environmental change.To empirically analyse the adequacy of this hypothesis, the study adopts a qualitative and explorative research methodology. This consists of a case study research design, exploring how and why environmental innovations are being triggered in transnational buildings at the interface between local and global societal dynamics in different urban settings. To this end, the in-house environmental management practices of four high environmental-profile multinational companies (ING, Andersen, ABN AMRO, and ffiM) are evaluated in three global cities, which altogether portray a sample of three different 'stateeconomy' combinations: Amsterdam (a democratic, partially state-regulated city with a well-developed environmental capacity), Sao Paulo (a democratic and free market economy context), and Beijing (a state-regulated urban setting). The combination of these three cities and four companies result in 12 case studies of global-local interception, which are investigated making use of personal interviews (in each company in the three cities as weIl as at city planning agencies), in addition to general observations and secondary literature.The findings of this research make it clear that, although showing differences, the greening of transnational buildings in the three global cities displays some similarities in certain aspects. First it can be noted that local public actors play a crucial role in activating the environmental reform of transnational buildings. Environmental policies deployed by urban environmental agencies, for instance, may actively trigger or seek to further policies of global companies, resulting in sustainable building practices. In addition, local public actors may develop environmental strategies through legal and economic instruments to attract transnational actors to invest in their local nodes, laying a kind of 'green carpet' for global companies, which would favour certain nodes of the network society for their good environmental performance.Secondly, local public actors developing sustainable building policies in cooperation with a multinational company tend to get environmental innovations started also at the level of the 'space of flows', that is, at the level of global company strategies. However, the expectation to see these policies materialise in other urban nodes of the network society does not always turn out to be realistic, resulting too often in weaker corporate environmental policies as compared to original regimes striven in nodes working in citycompany cooperation.Third, the research observes that successful cases of global in-house corporate environmental management require companies to 'learn' how to deal with the interaction between the space of flows and the space of place. These companies may pursue a global environmental policy, which, while determining its own standards of in-house environmental performance, always follows the strictest regime in place, whether originated from public policies or from the company's environmental policy. In so doing, such companies are making their sustainable building goals work at all nodes of the network society, regardless the lack of incentives from local agencies. Such approach may not only trespass or by-pass local environmental policies and standards by implementing company strategies more or less autonomously. In some cases it may also activate environmental policies of urban agencies, to be applied in other buildings in the same city. Based on the observations above, this study demonstrates how the realms of urban environmental management and corporate environmental management are not conflicting, as both cities and companies seek to optimise the use of finite resources such as energy and water and ensure sustainability. However a contradiction to be noted regards the shortterm increase in capital expenditure due to the investments sustainable buil ding involves, which goes against the profit component of the corporate management discourse. This research makes it clear that the institutionalisation of sustainable building practices in corporate premises has to a certain extent to be activated by urban policies. In that sense, although examples of market actors prompting environmental change are numerous, the role of public authorities remains crucial in activating the greening of transnational buildings, regardless the different (political-economic) urban settings.On the other hand, this research also demonstrates that, beyond multinationals, global market actors as developers and manufacturers are turning into prime agents of this ecological modernisation process, forming a bridge from locality to locality in the transcending of environmental change: distributing new solutions of environmental management, new technologies, new approaches of urban policies, and so. forth. It thereby supports the statement that global market actors are one if not the main engine for launching environmental innovations in transnational urban spaces. In this light, the global virtuous circle of urban environmental reform seems to have been triggered. Yet, to be thoroughly efficient, such virtuous circ1e needs to be ignited by adequate public policies, to be elaborated in accordance with the specificity of each space of place

Correlation of mycelial growth rate with other characters in evolved genotypes of Aspergillus nidulans

Fungal populations can adapt to their environment by the generation and fixation of spontaneous beneficial mutations. In this study we examined whether adaptation, measured as an increased mycelial growth rate, has correlated responses in the filamentous fungus Aspergillus nidulans with several other metric characters that could be important fitness components (colony forming units, germination speed, and biomass formation). Studying 60 populations that had evolved over 800 generations by experimental evolution, we find that only mycelial growth rate increased during adaptation to growing on solid medium. We further found that among evolved strains colony forming units is negatively correlated with mycelial growth rate and that colony forming units and biomass formation show a positive correlation. Our results give insight into changes in fungal phenotype as a result of adaptation and suggest that mycelial growth rate is the only available target of selectio

Modelling colony population growth in the filamentous fungus Aspergillus nidulans

Filamentous fungi are ubiquitous in nature and have high societal significance, being both major (food-borne) pathogens and important industrial organisms in the production of antibiotics and enzymes. In addition, fungi are important model organisms for fundamental research, such as studies in genetics and evolutionary biology. However, mechanistic models for population growth that would help understand fungal biology and fundamental processes are almost entirely missing. Here we present such a mechanistic model for the species Aspergillus nidulans as an exemplar of models for other filamentous fungi. The model is based on physiological parameters that influence colony growth, namely mycelial growth rate and sporulation rate, to predict the number of individual nuclei present in a colony through time. Using population size data for colonies of differing ages, we find that our mechanistic model accurately predicts the number of nuclei for two growth environments, and show that fungal population size is most dependent on changes in mycelial growth rate. (c) 2012 Elsevier Ltd. All rights reserved

Degradation of guar gum by intestinal bacteria

Guar gum is widely used in the food industry as a thickening agent. Guar and other galactomannans are ingested as a normal part of the human diet. Guar is completely degraded in the large intestine. Often large amounts of gas are produced. The objective of the study was to determine which species are responsible for the degradation of guar in the GI tract. It was observed that only a limited number of species is able to degrade and ferment guar. Guar degrading strains could be isolated from faecal samples of all volunteers and in 90% of the saliva of volunteers. The main species isolated from humans were Bifidobacterium dentium and Clostridium butyricum. From several samples of animal faeces Streptococcus bovis could be isolated. In addition some strains of Bacteroides ovatus were able to degrade guar to a limited extent. Fermentation resulted in the production of short-chain fatty acids and, when Cl. butyricum was present, in a large gas production. Competition experiments showed that Cl. butyricum degrades guar faster than both other species under simulated physiological conditions. It was concluded that Cl. butyricum is the main guar degrading species and the causative agent of the gas formation after guar intake

Fitness-associated sexual reproduction in a filamentous fungus

Sex is a long-standing evolutionary enigma. Although the majority of eukaryotes reproduce sexually at least sometimes [1-3], the evolution of sex from an asexual ancestor has been difficult to explain because it requires sexually reproducing lineages to overcome the manifold costs of sex, including the destruction of favorable gene combinations created by selection [4, 5]. Conditions for the evolution of sex are much broader if individuals can reproduce either sexually or asexually (i.e., facultative sex) and allocate disproportionately more resources to sex when their fitness is low (fitness-associated-sex or FAS [6-10]). Although facultatively sexual organisms have been shown to engage in more sex when stressed [11], direct evidence for FAS is lacking. We provide evidence using 53 genotypes of the filamentous fungus Aspergillus nidulans in a reciprocal transplant experiment across three environments. Different genotypes achieved highest fitness in different environments and genotypes invested relatively more in sex in environments in which their fitness was lower, showing that allocation to sexual reproduction is a function of how well-adapted a genotype is to its environment. FAS in A. nidulans is unlikely to have evolved as a strategy to resist or avoid stress because asexual spores are more dispersive and equally resistant [12, 13]