Galactosamine and mannosamine are integral parts of bacterial and fungal extracellular polymeric substances

Extracellular polymeric substances (EPS) are produced by microorganisms and interact to form a complex matrix called biofilm. In soils, EPS are important contributors to the microbial necromass and, thus, to soil organic carbon (SOC). Amino sugars (AS) are used as indicators for microbial necromass in soil, although the origin of galactosamine and mannosamine is largely unknown. However, indications exist that they are part of EPS. In this study, two bacteria and two fungi were grown in starch medium either with or without a quartz matrix to induce EPS production. Each culture was separated in two fractions: one that directly underwent AS extraction (containing AS from both biomass and EPS), and another that first had EPS extracted, followed then by AS determination (exclusively containing AS from EPS). We did not observe a general effect of the quartz matrix neither of microbial type on AS production. The quantified amounts of galactosamine and mannosamine in the EPS fraction represented on average 100% of the total amounts of these two AS quantified in cell cultures, revealing they are integral parts of the biofilm. In contrast, muramic acid and glucosamine were also quantified in the EPS, but with much lower contribution rates to total AS production, of 18% and 33%, respectively, indicating they are not necessarily part of EPS. Our results allow a meaningful ecological interpretation of mannosamine and galactosamine data in the future as indicators of microbial EPS, and also attract interest of future studies to investigate the role of EPS to SOC and its dynamics

Espaços, Processos e Relações de Vulnerabilidade Ambiental na Cidade de Santa Cruz do Sul (RS): construindo caminhos no campo da justiça ambiental

Nowadays it can be observed that the urban environment is highly influenced by spatial occupation activities, which are capable to shape its social, cultural, economic and political aspects. Space modification activities, such as the resources exploitation, frequently create interactions between social actors (also known as environmental conflict). These interactions are part of the establishment of environmental injustice situations in the exploited areas, being they also an important part in the study and search for solutions to these inequalities. This research proposes an analysis of the main environmental conflicts occurred in a two-year period in the urban area of Santa Cruz do Sul city (RS), through the listing of occurrences registered in the local newspaper (Gazeta do Sul) and the identification of the risk area s existing in the city. The analysis of these data, classified in predefined problem-situations, enabled the understanding of the vulnerabilization processes that affect populations with low income and limited political participation in the city. In reference of the way that the identified conflicts unfold, the analysis allowed the connection between the acquired data and the local sociopolitical processes, which led to the comprehension of their possible causes.Atualmente observa-se que o ambiente urbano é altamente influenciado pelas atividades de ocupação espacial, as quais são capazes de moldar seus aspectos sociais, culturais, econômicos e políticos. Os riscos resultantes de certas atividades de modificação do espaço, como a exploração de recursos, muitas vezes geram interações entre atores sociais (também conhecidas como conflitos socioambientais). Essas interações fazem parte do processo de instauração de situações de injustiça ambiental nos locais explorados, sendo elas também parte importante no estudo e busca por soluções para essas desigualdades. Esta pesquisa propõe uma análise dos principais conflitos socioambientais ocorridos em um período total de dois anos na área urbana de Santa Cruz do Sul (RS), por meio do levantamento de ocorrências registradas no jornal local (Gazeta do Sul) e da identificação das áreas de risco existentes na cidade. A análise desses dados, classificados em situações-problema predefinidas, possibilitou o entendimento dos processos de vulnerabilização que afetam as populações de baixa renda e pouca participação política na cidade. No que tange o modo como os conflitos identificados se desenrolam, as análises realizadas permitiram a conexão entre os dados obtidos e os processos sociopolíticos locais, o que levou à compreensão de suas possíveis causas

Galactosamine and mannosamine are integral parts of bacterial and fungal extracellular polymeric substances

Extracellular polymeric substances (EPS) are produced by microorganisms and interact to form a complex matrix called biofilm. In soils, EPS are important contributors to the microbial necromass and, thus, to soil organic carbon (SOC). Amino sugars (AS) are used as indicators for microbial necromass in soil, although the origin of galactosamine and mannosamine is largely unknown. However, indications exist that they are part of EPS. In this study, two bacteria and two fungi were grown in starch medium either with or without a quartz matrix to induce EPS production. Each culture was separated in two fractions: one that directly underwent AS extraction (containing AS from both biomass and EPS), and another that first had EPS extracted, followed then by AS determination (exclusively containing AS from EPS). We did not observe a general effect of the quartz matrix neither of microbial type on AS production. The quantified amounts of galactosamine and mannosamine in the EPS fraction represented on average 100% of the total amounts of these two AS quantified in cell cultures, revealing they are integral parts of the biofilm. In contrast, muramic acid and glucosamine were also quantified in the EPS, but with much lower contribution rates to total AS production, of 18% and 33%, respectively, indicating they are not necessarily part of EPS. Our results allow a meaningful ecological interpretation of mannosamine and galactosamine data in the future as indicators of microbial EPS, and also attract interest of future studies to investigate the role of EPS to SOC and its dynamics

Galactosamine and mannosamine are integral parts of bacterial and fungal extracellular polymeric substances

Gefördert durch den Publikationsfonds der Universität Kasse