Evaluation of the Atibaia River water quality using Lecane bulla as a test organism / Avaliação da qualidade das águas do Rio Atibaia usando Lecane bulla como organismo teste

In view of the diversity of environments found in the Brazilian territory, it is understandable that the use of native species can provide more relevant information for ecotoxicological studies. The purpose of this work was to evaluate the quality of water samples from the Atibaia River in an area that is under the influence of petroleum refinery using a native test-organism and submitting the data to PCA statistical analysis. Therefore, acute toxicity assays with Lecane bulla (Rotifera) were performed in four locations of the river, as well as physical-chemical analyses. Sampling was drawn in the dry and rainy seasons. The bioassays were static and lasted 48 hours; dead organisms were quantified at the end of the tests. Toxicological differences among the samples/per location and control were compared by means of the Analysis of Variance. Physical-chemical and mortality variables were simultaneously analyzed by multivariate analysis of the principal components and the Pearson correlation coefficient. Water samples from the exit of the refinery stabilization pond (location S.1) were toxic to L. bulla in both seasons, with significant differences in relation to the control and between the seasons. The statistical treatment of data showed that mortality was strong and positively correlated with total hardness, chlorides and EC, which together with pH presented higher values in location S.1, in the dry and in the rainy seasons. Due to its sensibility to the quality of the Atibaia river water samples, the potential use of L. bulla for ecotoxicological studies as an alternative test organism could be demonstrated.(AU)

Em virtude da diversidade de ambientes encontrada no território nacional, o uso de espécies nativas em estudos toxicológicos constitui assunto de extrema relevância. Este trabalho objetivou avaliar a qualidade das águas do rio Atibaia, em uma região sob influência de uma refinaria de petróleo utilizando-se um organismo-teste nativo, e aplicando-se o método estatístico multivariado análise de componentes principais (PCA). Ensaios de toxicidade aguda com o rotífero Lecane bulla (Rotifera) e análises físico-químicas foram realizados com amostras obtidas em quatro diferentes pontos do rio em questão. As amostragens ocorreram nas estações seca e chuvosa. Os bioensaios foram estáticos e duraram 48 horas; organismos mortos foram quantificados no final dos testes. Diferenças toxicológicas entre as amostras de cada ponto e o controle foram comparadas por análise de variância. As variáveis físico-químicas e a mortalidade foram simultaneamente submetidas à análise multivariada dos componentes principais e pela correlação de Pearson. Amostras de água retiradas da saída da lagoa de estabilização (ponto S.1) foram tóxicas ao organismo L. bulla nas duas estações, com diferenças significativas em relação ao controle e entre as estações. O tratamento estatístico dos dados demonstrou que a mortalidade correlacionou-se forte e positivamente com parâmetros como dureza total, cloretos e EC, e, com o pH, apresentou valores maiores no ponto S.1 em ambas as estações. A sensibilidade apresentada pela espécie L. bulla em relação à qualidade das amostras da água do rio Atibaia indicou que este organismo apresenta potencial de uso para estudos de ecotoxicologia, podendo ser futuramente empregado como organismo-teste alternativo.(AU)

Optimization of lipids production by Cryptococcus laurentii 11 using cheese whey with molasses

This study aimed the optimization of culture condition and composition for production of Cryptococcus laurentii 11 biomass and lipids in cheese whey medium supplemented with sugarcane molasses. The optimization of pH, fermentation time, and molasses concentration according to a full factorial statistical experimental design was followed by a Plackett-Burman experimental design, which was used to determine whether the supplementation of the culture medium by yeast extract and inorganic salts could provide a further enhancement of lipids production. The following conditions and composition of the culture medium were found to optimize biomass and lipids production: 360 h fermentation, 6.5 pH and supplementation of (g L-1): 50 molasses, 0.5 yeast extract, 4 KH2PO4, 1 Na2HPO4, 0.75 MgSO4•7H2O and 0.002 ZnSO4•H2O. Additional supplementation with inorganic salts and yeast extract was essential to optimize the production, in terms of product concentration and productivity, of neutral lipids by C. laurentii 11. Under this optimized condition, the production of total lipids increased by 133% in relation to control experiment (from 1.27 to 2.96 g L-1). The total lipids indicated a predominant (86%) presence of neutral lipids with high content of 16- and 18- carbon-chain saturated and monosaturated fatty acids. This class of lipids is considered especially suitable for the production of biodiesel.

Comparison of two lipid extraction methods produced by yeast in cheese whey

This work aimed to evaluate nine strains of yeast, previously identified as good producers of lipids in honey medium, for selecting the most suitable strain for the production of lipids in cheese whey medium and compared two well known extraction methods of lipids from the culture medium. The highest yield of total lipids was 1.27 g.L-1 produced by Cryptococcus laurentii 11. A comparison was made between the two culture media: cheese whey and liquid YEPG, and two lipid extraction methods: Bligh and Dyer and Folch et al. for C. laurentii. The experiments were performed with 2² full factorial design using two factors and two levels. Lipid content was higher in cheese whey and there was no difference in the extraction methods statistically. The method of Bligh and Dyer was used in preference to Folch et al. as it resulted in larger mean of total lipids.