ABSTRACT
Environmental pollution caused by petroleum-derived plastics continues to increase annually. Consequently, current research is interested in the search for eco-friendly bacterial polymers. The importance of Bacillus bacteria as producers of polyhydroxyalkanoates (PHAs) has been recognized because of their physiological and genetic qualities. In this study, twenty strains of Bacillus genus PHA producers were isolated. Production was initially evaluated qualitatively to screen the strains, and subsequently, the strain B12 or Bacillus sp. 12GS, with the highest production, was selected through liquid fermentation. Biochemical and molecular identification revealed it as a novel isolate of Bacillus cereus. Production optimization was carried out using the Taguchi methodology, determining the optimal parameters as 30 °C, pH 8, 150 rpm, and 4% inoculum, resulting in 87% and 1.91 g/L of polyhydroxybutyrate (PHB). Kinetic studies demonstrated a higher production within 48 h. The produced biopolymer was analyzed using Fourier-transform infrared spectroscopy (FTIR), confirming the production of short-chain-length (scl) polyhydroxyalkanoate, named PHB, and differential scanning calorimetry (DSC) analysis revealed thermal properties, making it a promising material for various applications. The novel B. cereus isolate exhibited a high %PHB, emphasizing the importance of bioprospecting, study, and characterization for strains with biotechnological potential.
ABSTRACT
El objetivo del presente estudio fue evaluar la producción de blastosporas y conidios de diferentes aislados nativos de México del hongo entomopatógeno Isaria fumosorosea y de una cepa de colección mediante diferentes técnicas de propagación. En la producción de blastosporas se utilizaron 2 medios de cultivo líquidos (sumergidos), uno a base de casaminoácidos y el otro a base de peptona de colágeno como fuentes de nitrógeno, con glucosa como fuente de carbono en ambos. Para la producción de conidios, los hongos se cultivaron en agar papa dextrosa, a partir de esos cultivos se prepararon suspensiones de 1 x 10(6) conidios/ml para inocular matraces con caldo dextrosa Sabouraud, para iniciar así la fase líquida del cultivo bifásico, denominado también precultivo. Posteriormente con el precultivo y las suspensiones de conidios se inocularon bolsas con granos de arroz, que se incubaron durante 14 días para el cultivo bifásico y para la fermentación sólida, respectivamente. El aislado HIB-23 fue el que logró la más elevada concentración de blastosporas obtenida en el cultivo sumergido: 4,90 x 10(8) blastosporas/ml en el medio casaminoácidos; y en el medio con peptona de colágeno se obtuvieron 2,15 x 10(8) blastosporas/ml. La máxima producción de conidios en fermentación sólida la logró la cepa Pfr-612 (1,58 x 10(9) conidios/g), mientras que la máxima en cultivo bifásico correspondió al aislado HIB-30 (9,00 x 10(6) conidios/g). La fermentación sólida resultó ser el método más efectivo, con un promedio de 1,09 x 10(9) conidios/g, mientras que el cultivo bifásico fue el menos efectivo, con un promedio de 2,76 x 10(6) conidios/g. Para la producción de blastosporas en los medios sumergidos no se obtuvo diferencia significativa alguna.
The aim of this study was to evaluate the production of blastospores and conidia of different native isolates and a strain of Isaria fumosorosea using different propagation techniques. Two liquid culture media of casamino acids and peptone as nitrogen sources and glucose as carbon source for both media cultures were respectively used in the production of blastospores, while for the production of conidia, the fungi were grown in potato dextrose agar; from these cultures, solutions of conidia to a concentration of 1 x 10(6) per milliliter were prepared to inoculate flasks with Sabouraud dextrose broth for the liquid phase of the biphasic culture, also known as preculture. Subsequently, rice grain bags were inoculated with the preculture and the conidia solutions, which were incubated for 14 days for solid fermentation and biphasic culture, respectively. The HIB-23 isolate recorded a concentration of 4.90 x 10(8) blastospores/ml in the casamino acid medium, while a concentration of 2.15 x 10(8) blastospores/ml was obtained in the peptone collagen medium. For the Pfr-612 strain, the conidia production in solid-state fermentation was 1.58 x 10(9) conidia/g, and for HIB-30 in the biphasic culture of 9.00 x 10(6) conidia/g. Solid-state fermentation proved to be the most effective method with an average of 1.09 x 10(9) conidia/g, whereas the biphasic culture was the least effective method with 2.76 x 10(6) conidia/g; no significant difference was reported for the submerged production media.
Subject(s)
Spores, Fungal , Hypocreales , Culture Media , Fermentation , MexicoABSTRACT
The aim of this study was to evaluate the production of blastospores and conidia of different native isolates and a strain of Isaria fumosorosea using different propagation techniques. Two liquid culture media of casamino acids and peptone as nitrogen sources and glucose as carbon source for both media cultures were respectively used in the production of blastospores, while for the production of conidia, the fungi were grown in potato dextrose agar; from these cultures, solutions of conidia to a concentration of 1×106 per milliliter were prepared to inoculate flasks with Sabouraud dextrose broth for the liquid phase of the biphasic culture, also known as preculture. Subsequently, rice grain bags were inoculated with the preculture and the conidia solutions, which were incubated for 14 days for solid fermentation and biphasic culture, respectively. The HIB-23 isolate recorded a concentration of 4.90×108 blastospores/ml in the casamino acid medium, while a concentration of 2.15×108 blastospores/ml was obtained in the peptone collagen medium. For the Pfr-612 strain, the conidia production in solid-state fermentation was 1.58×109 conidia/g, and for HIB-30 in the biphasic culture of 9.00×106 conidia/g. Solid-state fermentation proved to be the most effective method with an average of 1.09×109 conidia/g, whereas the biphasic culture was the least effective method with 2.76×106 conidia/g; no significant difference was reported for the submerged production media.
