Optimization of a medium composition for the heterologous production of Alcaligenes faecalis penicillin G acylase in Bacillus megaterium.

Penicillin G acylase (PGA) is a strategic enzyme in the production processes of beta-lactam antibiotics. High demand for ß-lactam semisynthetic antibiotics explain the genetic and biochemical engineering strategies devoted towards novel ways for PGA production and application. This work presents a fermentation process for the heterologous production of PGA from Alcaligenes faecalis in Bacillus megaterium with optimization. The thermal stability from A. faecalis PGA is considerably higher than other described PGA and the recombinant enzyme is secreted to the culture medium by B. megaterium, which facilitates the separation and purification steps. Media optimization using fractional factorial design experiments was used to identify factors related to PGA activity detection in supernatant and cell lysates. The optimized medium resulted in almost 6-fold increased activity in the supernatant samples when compared with the basal medium. Maximum enzyme activity in optimized medium composition achieves values between 135 and 140 IU/ml. The results suggest a promising model for recombinant production of PGA in B. megaterium with possible extracellular expression of the active enzyme.

Isolamento de Alcaligenes faecalis em peixe Betta splendens Regan, 1910 no Brasil / Isolation of Alcaligenes faecalis in fish Betta splendens Regan, 1910 in Brazil

Descreve-se um caso de infecção por Alcaligenes faecalis em peixe ornamental Betta splendens, incluindo avaliação clínica, patológica e bacteriológica. Um peixe fêmea, com peso de 16 g, inicialmente demonstrou discreta lesão escoriativa no tegumento, inapetência, emagrecimento progressivo, letargia, dispneia e aumento de volume na região lateral esquerda. Constataram-se em necropsia a presença de exoftalmia bilateral, opacidade de córnea, ascite e abscesso no subcutâneo provocando distensão da cavidade celomática. As alterações histológicas da pele se caracterizaram por abscesso, necrose, hemorragia e infiltrado inflamatório constituído principalmente de heterófilos. No exame microbiológico com exsudato e sangue venoso isolou-se exclusivamente A. faecalis.(AU)

This paper aimed to describe one case of infection by Alcaligenes faecalis in an ornamental fish Betta splendens, including clinical, pathological, and bacteriological evaluation. A female fish weighing 16 g initially showed discrete ulcerative lesions in the integument, inappetence, progressive weight loss, lethargy, dyspnea, and increased volume in the left lateral region. Necropsy revealed bilateral exophthalmia, corneal opacity, ascites, and subcutaneous abscess causing distension of the celomatic cavity. Histological changes of the skin were characterized by abscess, necrosis, hemorrhage, and inflammatory infiltrate consisting mainly of heterophils. Microbiological assays using the exudates and venous blood isolated exclusively A. faecalis.(AU)

Isolamento de Alcaligenes faecalis em peixe Betta splendens Regan, 1910 no Brasil / Isolation of Alcaligenes faecalis in fish Betta splendens Regan, 1910 in Brazil

Descreve-se um caso de infecção por Alcaligenes faecalis em peixe ornamental Betta splendens, incluindo avaliação clínica, patológica e bacteriológica. Um peixe fêmea, com peso de 16 g, inicialmente demonstrou discreta lesão escoriativa no tegumento, inapetência, emagrecimento progressivo, letargia, dispneia e aumento de volume na região lateral esquerda. Constataram-se em necropsia a presença de exoftalmia bilateral, opacidade de córnea, ascite e abscesso no subcutâneo provocando distensão da cavidade celomática. As alterações histológicas da pele se caracterizaram por abscesso, necrose, hemorragia e infiltrado inflamatório constituído principalmente de heterófilos. No exame microbiológico com exsudato e sangue venoso isolou-se exclusivamente A. faecalis.(AU)

This paper aimed to describe one case of infection by Alcaligenes faecalis in an ornamental fish Betta splendens, including clinical, pathological, and bacteriological evaluation. A female fish weighing 16 g initially showed discrete ulcerative lesions in the integument, inappetence, progressive weight loss, lethargy, dyspnea, and increased volume in the left lateral region. Necropsy revealed bilateral exophthalmia, corneal opacity, ascites, and subcutaneous abscess causing distension of the celomatic cavity. Histological changes of the skin were characterized by abscess, necrosis, hemorrhage, and inflammatory infiltrate consisting mainly of heterophils. Microbiological assays using the exudates and venous blood isolated exclusively A. faecalis.(AU)