Screening and identification of a Bacillus amyloliquefaciens strain for aqueous enzymatic extraction of medium-chain triglycerides

Geographic Pattern of Variations in Chemical Composition and Nutritional Value of Cinnamomum camphora Seed Kernels from China

Cinnamomum camphora (camphor tree) is an important non-conventional edible plant species found in East Asia. Here, a detailed characterization for the chemical composition and nutritional value of C. camphora seed kernels (CCSKs) collected from different regions in China is provided. The results showed that there were significant differences among the CCSK samples in weights (1000 fruits, 1000 seeds and 1000 kernels), proximate composition, minerals, phenolics, flavonoids and amino acid contents. The highest contents of oil (62.08%) and protein (22.17%) were found in the CCSK samples collected from Chongqing and Shanghai, respectively. The highest content of mineral in the CCSK samples was K (4345.05-7186.89 mg/kg), followed by P (2735.86-5385.36 mg/kg), Ca (1412.27-3327.37 mg/kg) and Mg (2028.65-3147.32 mg/kg). The CCSK sample collected from Guizhou had the highest levels of total phenolic and flavonoid contents (TPC and TFC), while that from Chongqing had the lowest levels. In addition, the most abundant fatty acid in the CCSK samples was capric acid (57.37-60.18%), followed by lauric acid (35.23-38.29%). Similarities in the fatty acid composition among the CCSK samples were found. The CCSK sample collected from Guizhou had the highest percentage (36.20%) of essential amino acids to total amino acids, and Chongqing had the lowest value (28.84%). These results indicated that CCSK may be developed as an excellent source of plant-based medium-chain oil, protein, dietary fiber, minerals, phytochemicals and essential amino acids.

Regulation mechanism of magnetic field on pectinase and its preliminary application in postharvest sapodilla (Manilkara zapota)

In this study, regulation mechanism of magnetic field on pectinase was investigated and it was preliminarily applied in postharvest sapodilla. Results indicated pectinase activity decreased by 44 % when treated by magnetic field (3 mT, 0.5 h) with kinetic parameters V_max/K_m decreasing from 0.799 to 0.366 min. The optimal temperature (48 °C) and pH (4.8) of pectinase was not altered by magnetic field but Ca²⁺ at 0.05 mol/L strengthened its regulation effect. Ultraviolet and fluorescence spectra suggested tyrosine and tryptophan residues in treated pectinase became more hydrophobic while opposite in phenylalanine. CO, CNH, COO^- groups in pectinase were also influenced, resulting in decreased β-sheet (from 53 % to 49 %), increased random coil (from 20 % to 22 %) and β-turn content (from 27 % to 29 %). More importantly, the firmness of treated sapodilla remained 45 % of maximum at 12 days' storage. Our findings provided new insights to illustrate the role of magnetic field in fruit preservation.

Highly efficient deproteinization with an ammonifying bacteria Lysinibacillus fusiformis isolated from brewery spent diatomite

To explore a new method for bio-regeneration of high-protein brewery spent diatomite, an ammonifying bacteria (BSD1) was screened out from it and identified as Lysinibacillus fusiformis. The protein degradation characteristics of BSD1 was studied with rice protein as the sole nitrogen source. Maximum protein degradation activity was obtained when BSD1 was inoculated with an inoculum of 5% into a medium with glucose as carbon source and initial pH value of 7.0 and incubated at 30°C for 48 h. In this optimal condition, protein concentration decreased from 156.8 mg/L to 19.2 mg/L, and protein degradation efficiency of BSD1 reached 88%. Free amino acid analysis showed that the content of Phe, Tyr, Pro, Ala, Lys, Thr and His increased in protein degradation process. After degradation, NH₄⁺N concentration producing in medium supernatant reached 232.2 mg/L. These results indicated the strain BSD1 could transform proteins into free amino acids and eventually convert them to ammonium or ammonia. Furthermore, strain BSD1 could also be used for deproteinization of brewery spent diatomite and 51% of proteins in spent diatomite were degraded. After biological deproteinization the specific surface area and total pore volume of diatomite improved obviously. These results illustrated that the application of strain BSD1 for bio-regeneration of high-protein brewery spent diatomite was efficient and feasible.

Mutagenesis and characterization of a Bacillus amyloliquefaciens strain for Cinnamomum camphora seed kernel oil extraction by aqueous enzymatic method

The purpose of the present study was to increase the proteinase activity of the strain NCU116 by combining ultraviolet irradiation and N-methyl-N'-nitro-N-nitroso guanidine treatment, in order to enhance the efficiency of Cinnamomum camphora seed kernel oil (CCSKO) extraction by aqueous enzymatic method (AEM). The mutated strain, designated as NCU116-1, was screened out by the ratio of hydrolytic zone diameter to colony diameter on skim milk plate. The proteinase activity (9116.1 U/ml) of NCU116-1 was increased by 31.9% compared with the parental strain. The extracellular enzymes produced by NCU116-1 included proteinase, pectase, glucoamylase, cellulase and amylase. The proteinase had the maximum activity at 50 °C. Its optimum temperature and pH value were approximately 45 °C and 8.0 respectively. Mn²⁺ was an activator of neutral proteinase. The glucoamylase had the maximum activity at 35 °C, and was activated by Cu²⁺, Fe³⁺ and Mn²⁺. Its optimum temperatures and pH value were 35 °C and 8.0 respectively. The pectinase had the maximum activity at 40 °C, and was activated by Ca²⁺ and Mn²⁺. Its optimum temperatures and pH value were 35-40 °C and 6.0 respectively. The optimum conditions of CCSKO extraction by AEM were also investigated. The results suggested that the best amount of enzyme solution and enzymolysis time were 20% (v/v) and 4 h, respectively. The oil extraction rate was 95.2% under these conditions. Thus, a suitable mutated strain was selected for CCSKO extraction by AEM and the optimum extraction conditions were determined.