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Hassan ME, Ibrahim GE, Abdella MAA. Enhancement of β-galactosidase catalytic activity and stability through covalent immobilization onto alginate/tea waste beads and evaluating its impact on the quality of some dairy products. Int J Biol Macromol 2024; 278:134810. [PMID: 39154676 DOI: 10.1016/j.ijbiomac.2024.134810] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2024] [Revised: 08/04/2024] [Accepted: 08/14/2024] [Indexed: 08/20/2024]
Abstract
The current study aimed to evaluate the hydrolysis of whole fat milk (WFM) and sweet whey (SW) using β-galactosidase (β-gal) after covalent immobilization onto activated alginate/tea waste (Alg/TW) beads as a novel carrier. The optimum temperature for free and Alg/TW/β-gal was 40 °C and the ideal pH was 7.0. However, Alg/TW/β-gal displayed better stabilities at high temperatures and a wide pH range. Additionally, the value of Km and Vmax for Alg/TW/β-gal was higher than the free enzyme. The Alg/TW/β-gal showed better residual activity (78.6 %) after 90 storage days at 4 °C. The reusability of Alg/TW/β-gal was very good as it conserved its full activity after 15 consecutive cycles and conserved 93 % of its initial activity after 10 cycles with ONPG (O-nitrophenyl-β-D-galactopyranoside) and lactose as a substrate, respectively. The impact of Alg/TW/β-gal on WFM and SW using HPLC analysis revealed a remarkable decrease in lactose concentration and increase of glucose and galactose concentrations. The SW exhibited higher degree of lactose hydrolysis (97.3 %) compared to WFM (62.4 %). Besides, SW had a prominent increase in total phenolic content (96.8 mg/L) compared to WFM (54.3 mg/L). The antioxidant activity had increased after enzyme treatment in both WFM and SW. The GC-MS analysis for volatile compounds identified twenty-five flavour constituents. Finally, Alg/TW/β-gal has a potential application for obtaining healthy, acceptable, and commercial dairy products of low lactose.
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Affiliation(s)
- Mohamed E Hassan
- Chemistry of Natural and Microbial Products Department, Pharmaceutical and Drug Industries Research Institute, National Research Centre, Dokki, Giza 12622, Egypt; Centre of Excellence, Encapsulation Nanobiotechnology Group, National Research Centre, Dokki, Giza 12622, Egypt
| | - Gamil E Ibrahim
- Chemistry of Flavour and Aroma Department, Food Industries and Nutrition Research Institute, National Research Centre, Dokki, Giza 12622, Egypt
| | - Mohamed A A Abdella
- Chemistry of Natural and Microbial Products Department, Pharmaceutical and Drug Industries Research Institute, National Research Centre, Dokki, Giza 12622, Egypt.
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Zhou Z, He N, Han Q, Liu S, Xue R, Hao J, Li S. Characterization and Application of a New β-Galactosidase Gal42 From Marine Bacterium Bacillus sp. BY02. Front Microbiol 2021; 12:742300. [PMID: 34759900 PMCID: PMC8573354 DOI: 10.3389/fmicb.2021.742300] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 09/16/2021] [Indexed: 12/04/2022] Open
Abstract
β-Galactosidase plays an important role in medicine and dairy industry. In this study, a new glycoside hydrolase family 42 (GH42) β-galactosidase-encoding gene, gal42, was cloned from a newly isolated marine bacterium Bacillus sp. BY02 and expressed in Escherichia coli. Structural characterization indicated that the encoding β-galactosidase, Gal42, is a homotrimer in solution, and homology modeling indicated that it retains the zinc binding sites of the Cys cluster. The reaction activity of Gal42 was significantly increased by Zn2+ (229.6%) and other divalent metal ions (Mn2+, Mg2+, and Co2+), while its activity was inhibited by EDTA (53.9%). Meanwhile, the thermo-stability of the Gal42 was also significantly enhanced by 5 and 10 mM of zinc ion supplement, which suggested that the “Cys-Zn” motif played important roles in both structural stability and catalytic function. Furthermore, Gal42 showed effective lactose hydrolysis activity, which makes the enzyme hydrolyze the lactose in milk effectively. These properties make Gal42 a potential candidate in food technology.
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Affiliation(s)
- Zihan Zhou
- School of Basic Medicine, Qingdao University, Qingdao, China
| | - Ningning He
- School of Basic Medicine, Qingdao University, Qingdao, China
| | - Qi Han
- School of Basic Medicine, Qingdao University, Qingdao, China
| | - Songshen Liu
- School of Basic Medicine, Qingdao University, Qingdao, China
| | - Ruikun Xue
- School of Basic Medicine, Qingdao University, Qingdao, China
| | - Jianhua Hao
- Key Laboratory of Sustainable Development of Polar Fishery, Ministry of Agriculture and Rural Affairs, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, China.,Jiangsu Collaborative Innovation Center for Exploitation and Utilization of Marine Biological Resource, Lianyungang, China
| | - Shangyong Li
- School of Basic Medicine, Qingdao University, Qingdao, China
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Critical thresholds of 1-Octen-3-ol shape inter-species Aspergillus interactions modulating the growth and secondary metabolism. Sci Rep 2020; 10:11116. [PMID: 32632328 PMCID: PMC7338521 DOI: 10.1038/s41598-020-68096-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Accepted: 06/16/2020] [Indexed: 12/12/2022] Open
Abstract
In fungi, contactless interactions are mediated via the exchange of volatile organic compounds (VOCs). As these pair-wise interactions are fundamental to complex ecosystem, we examined the effects of inter-species VOCs trade-offs in Aspergillus flavus development. First, we exposed A. flavus to the A. oryzae volatilome (Treatment-1) with highest relative abundance of 1-Octen-3-ol (~ 4.53 folds) among the C-8 VOCs. Further, we examined the effects of gradient titers of 1-Octen-3-ol (Treatment-2: 100–400 ppm/day) in a range that elicits natural interactions. On 7-day, VOC-treated A. flavus displayed significantly reduced growth and sclerotial counts (p < 0.01) coupled with higher conidial density (T2100-200 ppm/day, p < 0.01) and α-amylase secretion (T2200 ppm/day, p < 0.01), compared to the untreated sets. Similar phenotypic trends except for α-amylases were evident for 9-day incubated A. flavus in T2. The corresponding metabolomics data displayed a clustered pattern of secondary metabolite profiles for VOC-treated A. flavus (PC1-18.03%; PC2-10.67%). Notably, a higher relative abundance of aflatoxin B1 with lower levels of most anthraquinones, indole-terpenoids, and oxylipins was evident in VOC-treated A. flavus. The observed correlations among the VOC-treatments, phenotypes, and altered metabolomes altogether suggest that the distant exposure to the gradient titers of 1-Octen-3-ol elicits an attenuated developmental response in A. flavus characterized by heightened virulence.
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Fountain JC, Yang L, Pandey MK, Bajaj P, Alexander D, Chen S, Kemerait RC, Varshney RK, Guo B. Carbohydrate, glutathione, and polyamine metabolism are central to Aspergillus flavus oxidative stress responses over time. BMC Microbiol 2019; 19:209. [PMID: 31488075 PMCID: PMC6727485 DOI: 10.1186/s12866-019-1580-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 08/25/2019] [Indexed: 01/08/2023] Open
Abstract
Background The primary and secondary metabolites of fungi are critical for adaptation to environmental stresses, host pathogenicity, competition with other microbes, and reproductive fitness. Drought-derived reactive oxygen species (ROS) have been shown to stimulate aflatoxin production and regulate in Aspergillus flavus, and may function in signaling with host plants. Here, we have performed global, untargeted metabolomics to better understand the role of aflatoxin production in oxidative stress responses, and also explore isolate-specific oxidative stress responses over time. Results Two field isolates of A. flavus, AF13 and NRRL3357, possessing high and moderate aflatoxin production, respectively, were cultured in medium with and without supplementation with 15 mM H2O2, and mycelia were collected following 4 and 7 days in culture for global metabolomics. Overall, 389 compounds were described in the analysis which encompassed 9 biological super-pathways and 47 sub-pathways. These metabolites were examined for differential accumulation. Significant differences were observed in both isolates in response to oxidative stress and when comparing sampling time points. Conclusions The moderately high aflatoxin-producing isolate, NRRL3357, showed extensive stimulation of antioxidant mechanisms and pathways including polyamines metabolism, glutathione metabolism, TCA cycle, and lipid metabolism while the highly aflatoxigenic isolate, AF13, showed a less vigorous response to stress. Carbohydrate pathway levels also imply that carbohydrate repression and starvation may influence metabolite accumulation at the later timepoint. Higher conidial oxidative stress tolerance and antioxidant capacity in AF13 compared to NRRL3357, inferred from their metabolomic profiles and growth curves over time, may be connected to aflatoxin production capability and aflatoxin-related antioxidant accumulation. The coincidence of several of the detected metabolites in H2O2-stressed A. flavus and drought-stressed hosts also suggests their potential role in the interaction between these organisms and their use as markers/targets to enhance host resistance through biomarker selection or genetic engineering. Electronic supplementary material The online version of this article (10.1186/s12866-019-1580-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jake C Fountain
- USDA-ARS, Crop Protection and Management Research Unit, Tifton, GA, 31793, USA.,Department of Plant Pathology, University of Georgia, Tifton, GA, 31793, USA
| | - Liming Yang
- Department of Plant Pathology, University of Georgia, Tifton, GA, 31793, USA.,College of Biology and Environmental Science, Nanjing Forestry University, Nanjing, 210037, China
| | - Manish K Pandey
- International Crop Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana, 502324, India
| | - Prasad Bajaj
- International Crop Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana, 502324, India
| | | | - Sixue Chen
- Department of Biology, Genetics Institute, and Plant Molecular & Cellular Biology Program, University of Florida, Gainesville, FL, 32611, USA
| | - Robert C Kemerait
- Department of Plant Pathology, University of Georgia, Tifton, GA, 31793, USA
| | - Rajeev K Varshney
- International Crop Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana, 502324, India
| | - Baozhu Guo
- USDA-ARS, Crop Protection and Management Research Unit, Tifton, GA, 31793, USA.
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