Molecular Characterization and Heterologous Production of the Bacteriocin Peocin, a DNA Starvation/Stationary Phase Protection Protein, from Paenibacillus ehimensis NPUST1.

The production of a bacteriocin-like substance with antimicrobial activity, named peocin, by the probiotic Paenibacillus ehimensis NPUST1 was previously reported by our laboratory. The present study aimed to identify peocin and increase the peocin yield by heterologous expression in Escherichia coli BL21(DE3). Peocin was identified as a DNA starvation/stationary phase protection protein, also called DNA-binding protein from starved cells (Dps), by gel overlay and LC-MS/MS analysis. For mass production of peocin, fed-batch cultivation of E. coli was performed using a pH-stat control system. Purification by simple nickel affinity chromatography and dialysis yielded 45.3 mg of purified peocin from a 20-mL fed-batch culture (49.3% recovery). The biological activity of the purified peocin was confirmed by determination of the MIC and MBC against diverse pathogens. Purified peocin exhibited antimicrobial activity against aquatic, food spoilage, clinical and antibiotic-resistant pathogens. In an in vivo challenge test, zebrafish treated with purified peocin exhibited significantly increased survival rates after A. hydrophila challenge. The present study is the first to show the antimicrobial activity of Dps and provides an efficient strategy for production of bioactive peocin, which will aid the development of peocin as a novel antimicrobial agent with potential applications in diverse industries.

Effect of environmental factors on blood counts of Gambusia affinis caught at Brantas River watershed, Indonesia.

Background: Contamination of freshwater ecosystems has become a major issue as it threatens public water sources as well as aquatic life. It is important to predict changes in organism health, given a known number of environmental factors and pollutant concentrations, in order to better manage contaminants through biomarker analysis. This study aims to examine the ecosystem health of the Brantas River based on its environmental condition and the hematology profile of Gambusia affinis fish present in the river. This species was chosen because of its wide distribution along the Brantas River, and because it is very tolerant, adaptable, highly abundant, and easy to catch. Methods: The study area included 10 sampling sites along the Brantas River watershed. In total, six water quality parameters were observed (temperature, pH, dissolved oxygen (DO), biological oxygen demand (BOD), ammonia concentration, and phenol concentration) and hematology measurements consisted of erythrocyte, leucocyte, and micronuclei analyses. Results: The results showed that the upstream area of Brantas River, located in Batu, was the least polluted region, while Mojokerto was the most polluted. The erythrocyte level of Gambusia affinis caught in most sampling sites was quite low. Furthermore, research revealed that the status of Gambusia affinis' hematological profile was significantly correlated (p<0.05) with water quality parameters, particularly DO, BOD, ammonia, and phenol. Conclusions: It can be concluded from these results that the hematological profile of the fish is poor due to high levels of organic waste and harmful substances.

Perspectives on sustainable management of the Poso Lake (Indonesia) endemic ricefish, Oryzias nigrimas (Actinopterygii: Adrianichthyidae) / Perspectivas sobre el manejo sostenible del pez Oryzias nigrimas, endémico del Lago Poso en Indonesia (Actinopterygii: Adrianichthyidae)

Introduction: The endemic fishes of the ancient lakes of Sulawesi are under increasing threat. Objective: To evaluate the data and information available from a holistic management perspective and to formulate measures to conserve the endemic ricefish Oryzias nigrimas in Poso Lake, Indonesia. Methods: Collection of primary data from three stations around Lake Poso and literature study. Results: Threats to O. nigrimas include habitat degradation and loss, introduced alien species, and exploitation as a locally important food fish. Options to promote sustainable fisheries management include spatial and temporal limitations to minimise catch of gravid or brooding fish. Habitat protection should include measures to minimise impacts from activities which can reduce water quality and disturb or kill aquatic vegetation. Conclusion: Measures to prevent further O. nigrimas population decline are considered urgent and further research is recommended to fill identified knowledge gaps. Ex-situ conservation, including the development of captive breeding, could also contribute to a holistic O. nigrimas conservation strategy.

Introducción: Los peces endémicos de los antiguos lagos de Sulawesi están cada vez más amenazados. Objetivo: Evaluar los datos y la información disponible desde una perspectiva de gestión holística y formular medidas para conservar el pez endémico Oryzias nigrimas en el lago Poso, Indonesia. Métodos: Recopilación de datos primarios de tres estaciones alrededor del lago Poso y revisión de la literatura. Resultados: Las amenazas para O. nigrimas incluyen la degradación y pérdida del hábitat, la introducción de especies exóticas y la explotación como producto pesquero de importancia local. Las opciones para promover la ordenación pesquera sostenible incluyen limitaciones espaciales y temporales para minimizar la captura de peces grávidos o reproductores. La protección del hábitat debe incluir medidas para minimizar los impactos de las actividades que pueden reducir la calidad del agua y perturbar o matar la vegetación acuática. Conclusión: Las medidas para prevenir una disminución de la población de O. nigrimas se consideran urgentes y se recomienda realizar más investigaciones para llenar los vacíos de conocimiento identificados. La conservación ex situ, incluido el desarrollo de la cría en cautividad, también podría contribuir a una estrategia de conservación holística de O. nigrimas.