Enzyme là chất xúc tác sinh học có khối lượng phân tử lớn, enzyme được sử dụng rộng rãi trong công nghiệp thực phẩm. Mới đây, các nhà nghiên cứu đã sử dụng một phương pháp đơn giản để tổng hợp các peptide có hoạt tính sinh học bằng cách thủy phân protein bằng enzyme, đặc biệt là bằng enzyme cố định. Peptide có hoạt tính sinh học là một nhóm các phân tử sinh học nằm trong cấu trúc của protein và trở nên hoạt động sau khi phân tách khỏi protein. Trong bài báo này, nhóm nghiên cứu đã chế tạo được enzyme Bacillus protease cố định trên gel Ca-alginate. Ở điều kiện hoạt động tối ưu (pHop = 7, top = 50°C, τop = 35 phút), hoạt độ enzyme cố định đo được là 180,03 IU/mg, hiệu suất cố định Bacillus protease lên chất mang là 84,34 %. Kết quả cố định enzyme Bacillus protease trên Ca-alginate sẽ được sử dụng để tổng hợp các peptide ngắn có hoạt tính sinh học trong sữa đậu nành.

Water usage increased alongside its competitiveness due to its finite amount. Yet, many industries still rely on this finite resource thus recalling the need to recirculate their water for production. Circular bioeconomy is presently the new approach emphasizing on the 'end-of-life' concept with reusing, recycling, and recovering materials. Microalgae are the ideal source contributing to circular bioeconomy as it exhibits fast growth and adaptability supported by biological rigidity which in turn consumes nutrients, making it an ideal and capable bioremediating agent, therefore allowing water re-use as well as its biomass potential in biorefineries. Nevertheless, there are challenges that still need to be addressed with consideration of recent advances in cultivating microalgae in wastewater. This review aimed to investigate the potential of microalgae biomass cultivated in wastewater. More importantly, how it'll play a role in the circular bioeconomy. This includes an in-depth look at the production of goods coming from wastes tattered by emerging pollutants. These emerging pollutants include microplastics, antibiotics, ever-increasingly sewage water, and heavy metals which have not been comprehensively compared and explored. Therefore, this review is aiming to bring new insights to researchers and industrial stakeholders with interest in green alternatives to eventually contribute towards environmental sustainability.

Production of indole-3-acetic acid (IAA) is well documented in various studies for the bacteria that inhabit the rhizosphere of plants, but with roots of wet rice, the outstandings have been not yet elucidated. This study began with the isolation of bacteria type strain Azospirillum sp. and developed the investigation to a screening of their ability in IAA production. This screening conducted a selection of only bacteria that was capable of the production of IAA with its content of over 25 µg. mL-1 for sequencing. Of 10 isolates only one resulted from the type strain Azospirillum brasilense (A. brasilense) with a similarity of 100%. Various factors that influence A. brasilense in biosynthesizing IAA such as temperature, pH, nitrogen presence and concentration of tryptophan in the culture medium were examined. The results indicated that the culture conditions were suitable for IAA biosynthesis at pH 6.5, 30 °C, culture media with nitrogen, and 0.1% trytophan. The next survey on the role of the immobilization of this bacteria with microalgae in alginate was highlighted to its support in microalgal growth. With the co-immobilization of bacteria and microalgae, the density of Chlorella vulgaris was significantly increased during 15-day culture, inducing 2.2 times of cell content in culture batch microalgae immobilized A. brasilense higher than that free-bacteria.

Co-culture of microalgae and microorganisms, supported with the resulting synergistic effects, can be used for wastewater treatment, biomass production, agricultural applications and etc. Therefore, this study aimed to explore the role of Bacillus subtilis (B. subtilis) in tolerance against the harsh environment of seafood wastewater, at which these microalgal-bacterial flocs were formed by microalgae cultivation. In this present study, B. subtilis isolated from the cultivation medium of Chlorella vulgaris and exposed to different salinity (0.1-4% w/v sodium chloride) and various pH range to determine the tolerant ability and biofilm formation. Interestingly, this bacteria strain that isolated from microalgae cultivation medium showed the intense viability in the salt concentration exceeding up to 4% (w/v) NaCl but demonstrated the decrease in cell division as environmental culture undergoing over pH 10. Cell viability was recorded higher than 71% and 92% for B. subtilis inoculum in media with salt concentration greater than 20 gL-1 and external pH 6.5-9, respectively. This showed that B. subtilis isolated from microalgal-bacteria cocultivation exhibited its tolerant ability to survive in the extremely harsh conditions and thus, mitigating the stresses due to salinity and pH.

Nattokinase, which is an extracellular enzyme synthesized by Bacillus subtilis natto, is a medication for cardiovascular disease treatment. In this study, soybean seed was used as a substrate for culturing Bacillus subtilis natto in solid-state fermentation to produce nattokinase. The optimal culture parameters for solid-state fermentation to synthesize nattokinase by Bacillus subtilis natto were 2:50 (v:w) of the ratio of Bacillus subtilis natto pre-culture to the substrate, 42 h of fermentation time, and 3 cm of the thickness of the substrate. At this optimal culture parameter of solid-state fermentation by using Bacillus subtilis natto, the enzymatic activity of crude nattokinase was 7.13 ± 0.2, 16.24 ± 0.33, and 16.55 ± 0.06 (specific activity/mL), respectively. Furthermore, we aim to apply this study with large scale production initially. Thus, the ratio of reusing Bacillus subtilis natto in fermentation product to substrate for a new process of solid-state fermentation and circulation time of reusing Bacillus subtilis natto in new solid fermentation process were screened. The maximal enzymatic activity of crude nattokinase of 14.10 ± 0.18 (specific activity/mL) was found at 3:100 (w:w) of reusing Bacillus subtilis natto in fermentation product to substrate for a new process of solid-state fermentation. The suggestion for the circulation time of reusing Bacillus subtilis natto for new solid fermentation process was 2nd. The results of this study had provided the necessary information for further research on nattokinase.

Fish protein hydrolysate, which is released to the environment as tuna processing waste during the hydrolysis reaction of Sarda Orientalis’ black muscle, could be used as a nutritional source of nitrogen for food products because of its valuable properties in antioxidant effects. This study used Protamex protease (endopeptidase) to hydrolyze the tuna’s black muscle (TBM) and to produce fish protein hydrolysate (FPH) for producing nutritional food powder. To access the FPH production, optimized conditions of reaction in hydrolyzing TBM were determined by factorial experimental design with the Box–Behnken model at a ratio of 0.45% enzyme/substrate, 100% added water content and temperature of 56 °C for 4.0 h. Consequently, the FPH obtained with the optimized condition resulted in an average degree of hydrolysis of 7.72% in response to the required range of 5–20%. Moreover, this FPH was detected for compositions of amino acids and peptides with low molecular weight less than 14 kDa and was tested in high antioxidant activity of 70% at its concentration of 500 µg mL−1. This study has provided an efficient procedure to solve the solid waste of TBM from the seafood manufacturing factories and transformed it into valuable products in the food industry.

1Research Institute For Marine Fisheries, Ministry of Agriculture and Rural Development, 224 Le Lai Street, May Chai Ward, Ngo Quyen District, Hai Phong City 04218, Viet Nam. 2The University of Da Nang University of Science and Technology, 54 Nguyen Luong Bang Street, Hoa Khanh Bac Ward, Lien Chieu District, Da Nang City 50608, Viet Nam. 3Nguyen Tat Thanh University, 298A-300A Nguyen Tat Thanh Street, Ward 13, District 4, Ho Chi Minh 72820, Viet Nam. 4National Institute of Nutrition, 48B Tang Bat Ho Street, Pham Dinh Ho Ward, Hai Ba Trung District, Hanoi 11611, Viet Nam.

Red meat of Sarda orientalis is one of by-products of tuna processing industry, the source of Sarda orientalis red meat is abundant in Vietnam. Red meat of Sarda orientalis contained 27 % of protein and 0.53 % of lipid, thus, it was classified into lean fish meat and a perfect resource for protein hydrolysate production. The purpose of this research is to hydrolyze Sarda orientalis red meat by using protamex enzyme to obtain protein hydrolysates. The suitable parameters for hydrolysis reaction were reaction time of 4 h, ratio of Protamex enzyme to red meat of 0.4 % (based on the weight of red meat, w/w), and reaction temperature of 55 °C with the maximal value of degree of hydrolysis of 7.03 %. The highest degree of hydrolysis in this research can compare to previous researches.

Mục đích của nghiên cứu này sử dụng cơ thịt đỏ cá ngừ sọc dưa (Sarda Orientalis) để sản xuất protein thủy phân bằng phản ứng thủy phân với xúc tác NaOH. Cơ thịt đỏ cá ngừ sọc dưa là nguyên liệu thích hợp để sản xuất protein thủy phân khi hàm lượng protein (22,42 ± 0,26%) cao hơn so với các nguyên liệu và phụ phẩm thủy sản khác. Điều kiện phản ứng thủy phân tối ưu tương ứng với từng yếu tố ảnh hưởng được xác định: Nồng độ xúc tác NaOH 0,45 M; tỉ lệ cơ chất:thể tích xúc tác NaOH 1:18 (w:v); thời gian phản ứng 50 phút và nhiệt độ phản ứng 30°C. Hiệu suất thu hồi protein đạt giá trị cực đại 73,32 ± 1,29% ở điều kiện phản ứng thủy phân tối ưu. Nghiên cứu đã cung cấp những thông tin quan trọng cho ứng dụng xúc tác NaOH để thủy phân nguyên liệu và phụ phẩm thủy sản nhằm thu dịch protein thủy phân. Từ khóa: Cơ thịt đỏ cá ngừ sọc dưa, phản ứng thủy phân, xúc tác NaOH, hiệu suất thu hồi protein

Enzymes are catalysts for biochemical reactions in the cell's metabolism. Enzymes are highly specific in their action on substrates. Lipase (triacylglycerol acylhydrolase) is an unique enzyme which can catalyze various types of reactions such as hydrolysis, esterification, alcoholysis… In recent days, studying and applying immobilized lipase in catalyzing transesterification of biodiesel production has been receiving much attention. The increased demand for biodiesel and the difficulties in obtaining enough quantities of raw materials for its production are stimulating the search for alternative feedstocks. Among the various possibilities, the utilization of residual fatty materials, in particular oils and animal fat residues from the meat and fish processing industries, are increasingly seen as viable options for biodiesel production. This paper presents the results of producing fixed lipase enzyme on microparticle chitosan-Fe3O4. Microparticle is a complex of nano particles Fe3O4 being absorbed on chitosan so it has magnetic property. Enzyme links to microparticle through an intermediate bridge – glutaraldehyde. Free enzyme which is used to fix is commercical lipase enzyme of Sigma (Germany) being extracted from pancreas of pig. Under the optimum conditions (pH 6, 40oC), after 3 hours reaction, immoblized enzyme activity measured 185 IU/mg and the productivity of attaching lipase to the carrier ratio was 75.1%. With immobilized lipase, the result of testing the biodiesel synthesized by lipid from wastewater of the surimi fish fillets manufacturing. The fuel properties of the biodiesel were further analyzed. The characterizations of the produced biodiesel showed that it met Vietnam standart (TCVN 7717:2007). Also discussed are the questions related to the viability of using this type of feedstocks in biodiesel production.