Antimicrobial resistance of heterotrophic marine bacteria isolated from seawater and sands of recreational beaches with different organic pollution levels in southeastern Brazil: evidences of resistance dissemination

Antimicrobial resistance of marine heterotrophic bacteria to different antimicrobials agents were evaluated in seawater, dry and wet sands from three marine recreational beaches with different pollution levels. In all studied beaches, the greatest frequencies of resistance were found in relation to penicillin. on Gonzaguinha, the most polluted beach, 72.3% of all isolated strains showed simple resistance, whilst 8.33% had multiple resistance. The values found on Ilha Porchat beach, were 70.8% and 6.9% for simple and multiple resistances, respectively. on GuaraA(0), the less polluted beach, only 35.3% of isolated strains had simple resistance. Multiple resistance was not observed. While samples from Gonzaguinha and Ilha Porchat beach showed isolated strains resistant to seven and six different antimicrobial agents, respectively, samples from GuaraA(0) beach were resistant only to penicillin and erytromicin. The positive correlations obtained between the degree of seawater contamination and frequency and variability of bacterial resistance indicate that polluted marine recreational waters and sands are sources of resistant bacteria contributing thus, to the dissemination of bacterial resistance.

Evaluation of the Genotoxicity of Chitosan Nanoparticles for Use in Food Packaging Films

The use of nanoparticles in food packaging has been proposed on the basis that it could improve protection of foods by, for example, reducing permeation of gases, minimizing odor loss, and increasing mechanical strength and thermal stability. Consequently, the impacts of such nanoparticles on organisms and on the environment need to be investigated to ensure their safe use. In an earlier study, Moura and others (2008a) described the effect of addition of chitosan (CS) and poly(methacrylic acid) (PMAA) nanoparticles on the mechanical properties, water vapor, and oxygen permeability of hydroxypropyl methylcellulose films used in food packaging. Here, the genotoxicity of different polymeric CS/PMAA nanoparticles (size 60, 82, and 111 nm) was evaluated at different concentration levels, using the Allium cepa chromosome damage test as well as cytogenetic tests employing human lymphocyte cultures. Test substrates were exposed to solutions containing nanoparticles at polymer mass concentrations of 1.8, 18, and 180 mg/L. Results showed no evidence of DNA damage caused by the nanoparticles (no significant numerical or structural changes were observed), however the 82 and 111 nm nanoparticles reduced mitotic index values at the highest concentration tested (180 mg/L), indicating that the nanoparticles were toxic to the cells used at this concentration. In the case of the 60 nm CS/PMAA nanoparticles, no significant changes in the mitotic index were observed at the concentration levels tested, indicating that these particles were not toxic. The techniques used show promising potential for application in tests of nanoparticle safety envisaging the future use of these materials in food packaging.

Hematological analysis of Micropogonias Furnieri, Desmarest, 1823, Scianidae, from two estuaries of Baixada Santista, São paulo Brazil

Alterações hematológicas em peixes são consideradas uma importante ferramenta para avaliar processos patológicos decorrentes da exposição a poluentes ambientais. Micropogonias furnieri (Desmarest, 1823) (corvina) é comumente encontrada em regiões estuarinas e eventualmente está exposta a inúmeros contaminantes. No presente estudo foi avaliado o quadro hematológico de indivíduos de M. furnieri coletados na Baixada Santista: o Sistema Estuarino de Santos, considerado poluído, e o estuário do Rio Itanhaém (controle). Foram avaliados o número de Eritrócitos (Er), o Hematócrito (Ht), a taxa de Hemoglobina (Hb), o Volume Corpuscular Médio (VCM) e a Concentração de Hemoglobina Corpuscular Média (CHCM). Nos peixes coletados no Sistema Estuarino de Santos, os níveis de Ht foram significativamente menores, enquanto os níveis de CHCM e Hb foram significativamente mais altos, indicando que os prováveis efeitos estejam atribuídos aos diferentes níveis de contaminação encontrados nos estuários.

Dynamics of some limnological characteristics in pacu (Piaractus mesopotamicus) culture tanks as function of handling

Visando obter subsídios para um estudo da qualidade da água em tanques de piscicultura, realizou-se um experimento de 166 dias com uma espécie nativa, pacu (Piaractus mesopotamicus). Nos tanques foram testados dois níveis diferentes de proteína na dieta (16% e 34% de proteína bruta) e três densidades de estocagem (0,25; 0,50 e 0,77 peixes/m²). Dos resultados obtidos foi observado que a interação entre a densidade de estocagem e a duração do experimento interferiram nas variáveis bicarbonato e alcalinidade e a interação entre a densidade de estocagem e a porcentagem de proteína interferiram nas concentrações de CO2 livre e total, condutividade e pH (P < 0,05). A temperatura da água nos tanques variou significativamente ao longo do período estudado (P < 0,05), diminuindo gradativamente do verão para o inverno. Não houve diferença significativa no tempo de residência da água nos tanques (P > 0,05) durante a duração do experimento. Os demais parâmetros não sofreram interferência dos tratamentos ao longo do período de estudo.