Comparative study on production of a-Amylase from Bacillus licheniformis strains

Amylases: Biofilm Inducer or Biofilm Inhibitor?

Biofilm is a syntrophic association of sessile groups of microbial cells that adhere to biotic and abiotic surfaces with the help of pili and extracellular polymeric substances (EPS). EPSs also prevent penetration of antimicrobials/antibiotics into the sessile groups of cells. Hence, methods and agents to avoid or remove biofilms are urgently needed. Enzymes play important roles in the removal of biofilm in natural environments and may be promising agents for this purpose. As the major component of the EPS is polysaccharide, amylase has inhibited EPS by preventing the adherence of the microbial cells, thus making amylase a suitable antimicrobial agent. On the other hand, salivary amylase binds to amylase-binding protein of plaque-forming Streptococci and initiates the formation of biofilm. This review investigates the contradictory actions and microbe-associated genes of amylases, with emphasis on their structural and functional characteristics.

Comprehensive study on transglycosylation of CGTase from various sources

Transglycosylation is the in-vivo or in-vitro process of transferring glycosyl groups from a donor to an acceptor, which is usually performed by enzymatic reactions because of their simplicity, low steric hindrance, high region-specificity, low production cost, and mild processing conditions. One of the enzymes commonly used in the transglycosylation reaction is cyclodextrin glucanotransferase (CGTase). The transglycosylated products, catalyzed by CGTase, are widely used in food additives, supplements, and personal care and cosmetic products. This is due to improvements in the solubility, stability, bioactivity and length of the synthesized products. This paper's focus is on the importance of enzymes used in the transglycosylation reaction, their characteristics and mechanism of action, sources and production yield, and donor and acceptor specificities. Moreover, the influence of intrinsic and extrinsic factors on the enzymatic reaction, catalysis of glycosidic linkages, and advantages of CGTase transglycosylation reactions are discussed in detail.

Development of Simple Analytical Method for B-Group Vitamins in Nutritional Products: Enzymatic Digestion and UPLC-MS/MS Quantification

A method for the simultaneous determination of seven B-group vitamers including thiamine, riboflavin, nicotinamide, niacin, pyridoxine, pyridoxal, and pyridoxamine in nutritional products by using enzymatic digestion followed by LC-MS/MS quantification was studied. The LC-MS/MS conditions such as MS transitions, mobile phase programs, and ammonium formate buffer concentrations, and sample treatment procedures (e.g., concentrations of buffer solution, digestion temperature, and digestion time) were investigated. The analytical method performance was evaluated by multiple criteria such as selectivity, linearity, detection and quantification limits, repeatability, reproducibility, and recovery by using real sample matrices. The validated method was successfully applied to analyze vitamin B concentrations in different nutritional products like ultra-heat-treated milk, powdered milk, and nutritional powder. Vitamin B concentrations varied over a wide range from lower than detection limits to about 9000 µg/100 g, depending on vitamin groups, compound forms, and sample types. The measured concentrations of B-group vitamins in our samples were generally in good agreement with values of label claims.

Optimisation and production of alpha amylase from thermophilic Bacillus spp. and its application in food waste biodegradation

This study employed Bacillus spp. with α-amylase production isolated from Malaysian hot spring for domestic kitchen food waste treatment contained grains, vegetables, chicken and tuna that mimic the food waste discharge from domestic kitchens in Malaysian household. Results showed that Bacillus licheniformis HULUB1 and Bacillus subtilis SUNGB2 possess excellent amylolytic properties. Highest α-amylase activity was obtained when both isolates were cultivated at pH 6.0 and 65 °C with concentrations of 18.15 U/mL for HULUB1 and 22.14 U/mL for SUNGB2. Stability of α-amylase with significant levels of enzyme activity were recorded at 55-85 °C and pH 5.0-9.0. The extracted mixed α-amylase of HULUB1 and SUNGB2 showed greatest reduction were achieved at day 12 with 45% ± 0.03 solid content at 65 °C. While the mixed culture of HULUB1 and SUNGB2 displayed an enhanced effect on the food waste contents reduction with 43% ± 0.02 solid content at 45 °C after day 12. The findings showed that the combination of the two Bacillus spp. isolates possessed degradation of food wastes at faster rate than α-amylase. It was also pointed out that the standard food waste (SFW) and the treatment process assimilated for this study was suitable for the growth of Bacillus spp.

Potential Nutrition and Health Claims in Deastringed Persimmon Fruits (Diospyros kaki L.), Variety 'Rojo Brillante', PDO 'Ribera del Xúquer'

In Europe, nutrition and health claims made on food must be based on scientific evidence, which means a comprehensive evaluation by the European Food Safety Authority (EFSA) prior to authorisation. Processed foods are subject to numerous claims derived from the presence of bioactive compounds; however, natural food products, often the original sources of those compounds, are not habitually the subject of these claims. Although the consumption of persimmon fruit has important health benefits, up to date no specific health claims are authorised for this fruit. In this work, ‘Rojo Brillante’ persimmon fruits (Diospyros kaki L.), Protected Designation of Origin (PDO) ‘Ribera del Xúquer’ were characterized regarding the presence of fiber (soluble and insoluble), vitamin C (ascorbic and dehydroascorbic acids), carotenoids (neoxanthin, violaxanthin, β-cryptoxanthin, lycopene, β- carotene) and mineral elements (Fe, Cu, Zn, Mn, Ca, Mg, Na, K). Different fruit batches harvested in different seasons were analyzed by standardized analytical methods (Association of Official Analytical Chemists, AOAC), high-performance liquid chromatography with ultraviolet detection (HPLC-UV) and atomic absorption spectroscopy. Based on the results, Persimon^® is potentially able to show two nutrition claims “Source of fiber” and “Sodium-free/salt-free”. This work could set the ground for future studies and to start considering natural food products as candidates for the use of approved claims.

Stability of selected enzymes in saliva of pigs under different storage conditions: a pilot study

Stability of α-amylase (α-A), butyrylcholinesterase (BChE), lipase, adenosine deaminase (ADA) and total esterase activity (TEA) in two pools of porcine saliva was studied after 1 and 4 days at 4°C, and after 30, 90 and 360 days at -20° and -80°C. At 4°C, BChE, lipase and TEA were stable less than 1 day, α-A less than 4 days and ADA for up to 4 days. At -20°C, BChE and TEA were stable less than 30 days, α-A and lipase less than 90 days and ADA up to 360 days. At -80°C, TEA was stable less than 30 days, α-A and lipase less than 360 days, and BChE and ADA for up to 360 days.

Bacillus Cellulase Molecular Cloning, Expression, and Surface Display on the Outer Membrane of Escherichia coli

One of the main challenges of using recombinant enzymes is that they are derived from genetically-modified microorganisms commonly located in the intracellular region. The use of these recombinant enzymes for commercial purposes requires the additional processes of cell disruption and purification, which may result in enzyme loss, denaturation, and increased total production cost. In this study, the cellulase gene of Bacillus licheniformis ATCC 14580 was cloned, over-expressed, and surface displayed in recombinant Escherichia coli using an ice-nucleation protein (INP). INP, an outer membrane-bound protein from Pseudomonas syringae, was utilized as an anchor linker, which was cloned with a foreign cellulase gene into the pET21a vector to develop a surface display system on the outer membrane of E. coli. The resulting strain successfully revealed cellulase on the host cell surface. The over-expressed INP-cellulase fusion protein was confirmed via staining assay for determining the extracellular cellulase and Western blotting method for the molecular weight (MW) of cellulase, which was estimated to be around 61.7 kDa. Cell fractionation and localization tests demonstrated that the INP-cellulase fusion protein was mostly present in the supernatant (47.5%) and outer membrane (19.4%), while the wild-type strain intracellularly retained enzymes within cytosol (>61%), indicating that the INP gene directed the cellulase expression on the bacteria cell surface. Further studies of the optimal enzyme activity were observed at 60 °C and pH 7.0, and at least 75% of maximal enzyme activity was preserved at 70 °C.

Catalytic Properties of Amylolytic Enzymes Produced by Gongronella butleri Using Agroindustrial Residues on Solid-State Fermentation

Amylases catalyze the hydrolysis of starch, a vegetable polysaccharide abundant in nature. These enzymes can be utilized in the production of syrups, alcohol, detergent, pharmaceutical products, and animal feed formulations. The aim of this study was to optimize the production of amylases by the filamentous fungus Gongronella butleri by solid-state fermentation and to evaluate the catalytic properties of the obtained enzymatic extract. The highest amylase production, 63.25 U g^-1 (or 6.32 U mL^-1), was obtained by culturing the fungus in wheat bran with 55% of initial moisture, cultivated for 96 h at 25°C. The enzyme presented optimum activity at pH 5.0 and 55°C. The amylase produced was stable in a wide pH range (3.5-9.5) and maintained its catalytic activity for 1 h at 40°C. Furthermore, the enzymatic extract hydrolyzed starches from different vegetable sources, presenting predominant dextrinizing activity for all substrates evaluated. However, the presence of glucose was observed in a higher concentration during hydrolysis of corn starch, indicating the synergistic action of endo- and exoamylases, which enables the application of this enzymatic extract to produce syrups from different starch sources.

Optimization of some fermentation conditions for the production of extracellular amylases by using Chryseobacterium and Bacillus isolates from organic kitchen wastes

Amylolytic bacterial isolates were obtained by starch-agar plate method from municipal solid wastes. Six amylolytic bacteria were isolated and the best two isolates, named as DY and W1, were selected based on clear zone ratio. The 16S rDNA sequence analysis identified DY and W1 isolates as Chryseobacterium sp. and Bacillus sp., respectively. Amylase production was optimized using basal media. The maximum level of amylase production was achieved from Chryseobacterium and Bacillus isolates after 60 h and 48 h of cultivation, respectively. The optimal temperature, initial pH of the media, agitation and inoculum size were determined for the both isolates. Increased amylase production was observed when basal media were substituted with organic carbon and nitrogen sources. The optimum pH and temperature for amylase activity of the crude amylase of Chryseobacterium sp. were 5.0 and 50 °C, respectively and those of amylase from Bacillus sp. were pH 7.0 and 50 °C, correspondingly. The crude amylase from the Chryseobacterium sp. was stable at pH 5.0-6.0 and up to 40 °C but that from Bacillus sp. was stable at pH 7.0 and up to 30 °C. Amylases from both the isolates lost ∼50% activity when stored at room temperature for two days. Under the optimized fermentation conditions both Chryseobacterium and Bacillus isolates produced almost the similar amount of amylase with organic kitchen wastes compared to the basal media. Results reported herein support the notion that Chryseobacterium sp. and Bacillus sp. can be used to produce industrially important amylases by utilizing organic kitchen wastes.

Expression and Characterization of Geobacillus stearothermophilus SR74 Recombinant α-Amylase in Pichia pastoris

Geobacillus stearothermophilus SR74 is a locally isolated thermophilic bacteria producing thermostable and thermoactive α-amylase. Increased production and commercialization of thermostable α-amylase strongly warrant the need of a suitable expression system. In this study, the gene encoding the thermostable α-amylase in G. stearothermophilus SR74 was amplified, sequenced, and subcloned into P. pastoris GS115 strain under the control of a methanol inducible promoter, alcohol oxidase (AOX). Methanol induced recombinant expression and secretion of the protein resulted in high levels of extracellular amylase production. YPTM medium supplemented with methanol (1% v/v) was the best medium and once optimized, the maximum recombinant α-amylase SR74 achieved in shake flask was 28.6 U mL(-1) at 120 h after induction. The recombinant 59 kDa α-amylase SR74 was purified 1.9-fold using affinity chromatography with a product yield of 52.6% and a specific activity of 151.8 U mg(-1). The optimum pH of α-amylase SR74 was 7.0 and the enzyme was stable between pH 6.0-8.0. The purified enzyme was thermostable and thermoactive, exhibiting maximum activity at 65°C with a half-life (t₁/₂) of 88 min at 60°C. In conclusion, thermostable α-amylase SR74 from G. stearothermophilus SR74 would be beneficial for industrial applications, especially in liquefying saccrification.