This study aimed to evaluate the growth, survival rate, and resistance to acute hepatopancreatic necrosis disease (AHPND) of white leg shrimp (Penaeus vannamei) by using Lactobacillus plantarum, Lactobacillus fermentum, and Pediococcus pentosaceus mixed with feed, and at the same time supplying CNP in a ratio of 15:1:0.1 to the water. As a result, the treatments that shrimp were fed with feed containing lactic acid bacteria (LAB), especially L. plantarum, have increased shrimp growth, total hemocyte cells, granulocyte cells, and hyaline cells significantly (p < 0.05) in comparison to the control group. The supply of CNP to the water has promoted the intensity of V. parahaemolyticus effects on shrimp health and significantly decreased total hemocyte cells, granulocyte cells, and hyaline cells by 30–50% in the period after three days of the challenge, except in L. plantarum treatment, which had only a 20% decrease compared to other treatments. In CNP supplying treatments, the AHPND infected rate and mortality of shrimp were higher than those in other treatments. In summary, the supply of CNP had significantly reduced the shrimp’s immune response and promoted the susceptibility of shrimp to AHPND in both cases of use with and without LAB-containing diets.

High lipid (fats and oils) concentration contained in wastewater inhibits the activity of microbes in biological wastewater treatment systems. The lipids degradation capability of lipid-degrading bacteria was investigated for possible application in treatment of lipids-contaminated wastewater. One hundred and two bacterial isolates were isolated from 43 vegetable oil- contaminated wastewater samples of many food processing plants and restaurants in 5 districts of Can Tho city, Vietnam on LB medium. There were sixty-one isolates produced clear zones on Tw20 medium, only eleven of which were found to have the high ability to degrade vegetable oil in the contaminated wastewater. These eleven isolates were identified by PCR technique and DNA sequencing. The results of DNA sequencing were compared with GenBank database of NCBI by BLAT N software. The sequences from selected isolates showed high degrees of similarity to those of the GenBank references (between 97% and 99%). Two isolates belonged to Bacilli (18.18%) and nine isolates belonged to Gammaproteobacteria (81.82%). Based on Pi value (nucleotide diversity), Gammaproteobacteria group had the highest Theta values. Theta value (per sequence) from S of SNP for DNA polymorphism were calculated for each group and 11 strains of lipid-degrading bacteria had high genetic diversity. The results propose Acinetobacteria soli strain AL3 a potential bioproduct for wastewater treatment because of its high ability of lipid degradation and biosafety.

Nitrogen-fixing and phosphate-solubilizing bacterial diversity and population dynamics in the Acrisol and Ferrasol rhizosphere of sugarcane grown in Dong Nai province, the eastern of South Vietnam was studied. Soil rhizosphere samples were taken in three districts (sites) of this region. Physical and chemical characteristics of soil samples and total nitrogen-fixing and phosphate-solubilizing bacteria counts were determined by drop plate count method together with 16S rRNA gene fragments amplified from DNA using eubacterial universal primers (27F and 1492R). A total of 31 isolates were isolated on two media (Burk’s N-free and NBRIP) and all of them have ability of nitrogen fixation and phosphate solubilization together with IAA biosynthesis. Population of nitrogen-fixing and phosphate-solubilizing bacteria correlated with N total concentration and organic matter content in soil closely (P<0.05). The sequences from selected nitrogen-fixing and phosphate-solubilizing bacteria (12 isolates) showed high degrees of similarity to those of the GenBank references strains (between 98% and 99%). From 12 isolates, 7 belonged to Bacilli, while 2 were Beta-Proteobacteria, 1 was Acidobacteria and 2 were Bacteroides. Based on Pi value (nucleotide diversity), Bacilli group had the highest theta value and Theta values (persequence) from S of SNP for DNA polymorphism were calculated for each group and Bacilli group had the highest values in comparison to three groups. From these results showed that two strains (Bacillus megaterium B6 (Ferrasols) and Sphingomonas sp. P14 (Acrisols)) revealed promising candidates with multiple beneficial characteristics and they have the potential for application as inoculants adapted to poor soils and sugarcane tree because they are not only famous strains but also are safety strains for agricultural sustainable.

Nghiên cứu được thực hiện để phân lập, tuyển chọn vi khuẩn từ dạ cỏ cừu có khả năng tổng hợp phytase và tinh sạch phytase bao gồm phương pháp kết tủa protein bằng muối ammonium sulphate 80% và kết hợp sắc ký trao đổi ion trên gel DEAE-cellulose. Khối lượng phân tử protein được đánh giá bằng phương pháp điện di SDS-PAGE. Trong 16 chủng vi khuẩn dạ cỏ cừu có khả năng phân giải phytate, dòng vi khuẩn C8 được xác định có hàm lượng protein và phosphate cao nhất lần lượt là 0,320 mg/mL, 11,76 mg/mL. Kết quả giải trình tự vùng 16S rDNA của dòng vi khuẩn C8 khi so sánh với ngân hàng gen NCBI và đặc điểm vi khuẩn phân lập được từ dạ cỏ cừu cho thấy dòng vi khuẩn C8 xác định được mức tương đồng với dòng vi khuẩn Bacillus rugosus strain SPB7 ở mức tương đồng 93,16%. Phân đoạn phytase F1 thu được đạt hiệu suất thu hồi là 13,2 %, độ tinh sạch gấp 3,04 lần, hoạt tính tổng 8.733 U, hoạt tính đặc hiệu là 280 U/mg protein và khối lượng phân tử 34,9 kDa.

Một trăm chín mươi mốt dòng vi khuẩn được phân lập từ 93 mẫu nốt sần, rễ, thân cây đậu phộng (lạc) trồng tại 03 huyện miền núi tỉnh Bình Định (Vân Canh, Vĩnh Thạnh, An Lão). Các dòng vi khuẩn phân lập được đều tạo màng mỏng (pellicle), đều có khả năng cố định đạm, hòa tan lân và tổng hợp IAA. Trong nghiên cứu, 15 dòng vi khuẩn có đặc tính tốt được tuyển chọn để nhận diện bằng kỹ thuật PCR. Kết quả cho thấy 15 dòng này đều là vi khuẩn nội sinh. Các dòng vi khuẩn được nhận diện thuộc 6 chi, bao gồm chi Acinetobacter (5 dòng), chi Bacillus (4 dòng), chi Burkholderia (2 dòng), chi Klebsiella (2 dòng), chi Enterobacter (1 dòng) và chi Sphingomonas (1 dòng) với tỷ lệ tương đồng DNA từ 98-99%.