This study aims at investigating to follow the formation and development of biofloc aggregates in a system with the introduction of an in vitro selected bacterial consortium (Bacillus thuringiensis, Bacillus sp., Staphylococcus cohnii) in order to induce fast formation of biofloc and to compare it to the development of spontaneous formation biofloc. Two experimental groups were evaluated for biofloc formation, SFT and IFT. The first refers to spontaneous (conventional) formation of the flocs and the second to induced formation (IFT), achieved through the consortium of potentially inducing bacteria. Both treatments presented a constant increase of bioflocs, however, in the IFT treatment, the microbial aggregates were larger and more uniform. By the end of the experiment, we verified that the aggregates formed in the IFT showed higher volume and lower sedimentation rate in comparison to the spontaneously formed ones. The results show that domestication in microbial communities is efficient as related to bioflocs, reducing instability during its formation and development.
El objetivo del presente trabajo fue evaluar estirpes bacterianas con características probióticas, aisladas del tracto intestinal de camarones marinos (Litopenaeus vannamei). Ciento noventa y una (191) estirpes fueron evaluadas para su selección basada en pruebas fenotípicas y genotípicas incluyendo: factores de virulencia (elastasa, gelatinasa, caseinasa, lípasa e fosfolipasa), tolerancia a diferentes temperaturas (4°C e 40°C) y pHs (5 e 9), prueba de susceptibilidad a antimicrobianos, prueba de agregación, antagonismo y prueba de identificación molecular (secuenciamiento-gen 16S rRNA). Las estirpes identificadas fueron agrupadas en diferentes géneros: Bacillus, Vibrios, Staphylococcus y un grupo con representantes de diferentes géneros bacterianos. Fueron formados tres grupos bacterianos prioritarios atendiendo a la respuesta de las estirpes frente a las diferentes pruebas analizadas. La mayoría de las estirpes (66,45%) presentó resistência frente a la oxitetraciclina. Todas las estirpes presentaron susceptibilidad frente al cloranfenicol y la tetraciclina. Ninguna estirpe presentó antagonismo frente al patógeno Vibrio parahaemolyticus. De las 70 estirpes que formaron parte de los tres grupos prioritarios, 16 estirpes (22,85%) resultaron antagónicas frente a Vibrio harvey. Doce estirpes bacterianas mostraron resultados satisfactorios en la técnica de antagonismo cruzado. Fueron formados tres consorcios bacterianos con aquellas estirpes que cumplieron los requisitos como probiótico potencial.
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Introduction: Regular physical activity and outdoor leisure provide significant health benefits. In urban environments, issues related to the air microbiological quality have become a priority due to the pandemic situation we are experiencing. This study analyzed the aerial microbiota of outdoor public spaces, using a qualitative and quantitative approach in Brazilian coastal town.
Materials and methods: Three intra-urban areas were analyzed and characterizing according the thermo-hydrometric characteristics and vegetal cover. Bioaerosols were collected during the wet and dry seasons using the passive sampling technique with selective growth media for fungi and bacteria. Microbial groups were quantified on agar plates; colonies were randomly selected, purified and classified. The antibiotic resistance was evaluated against 6 antibiotics belonging to 6 classes.
Results: Bacteria were relatively more frequent than fungi in the three areas. Among isolates, bacteria represented from 76% (P1) to 90% (P3) of the suspended microbiota in the rainy season; in dry season, the percentages varied from 87% (P1) to 91% (P2 and P3). Genus Bacillus was the main representative of Gram positive and Enterobacter genus the most frequently identified among Gram-negative bacteria. Aspergillus and Penicillium genera were the dominant among fungi. Fifty per cent from bacterial strains analyzed were resistant to at least one of the tested antimicrobials.
Conclusion: Bacteria proved more abundant than fungi and more susceptible to climate and environmental changes in the leisure areas of the city. The monitoring of biological agents in the air is important for environmental management and population health.
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