Nostoc sp. VICCR1-1 was induced in order to form akinetes on the basis of nutrient modification. Phosphorus and iron were found to be the critical for akinete differentiation, especially when both elements were omitted. The number of akinete cells increased up to 20% when compared with culturing in BG11 0 medium (without N source). In addition, CaCl 2 played a role in heterocyst differentiation, and was able to induce heterocyst ranging between 30% and 46%. In order to prepare akinetes as inoculum, the dried form of akinetes was prepared by mixing it with montmorillonite clay. The inoculum with the amount of 2.8×10 6 cells m −2 was applied to rice (Oryza sativa) fields. After harvesting, the grain yields from chemical N fertilizer, vegetative cells, and akinete inoculum treatments were not significantly different. To monitor the persistence of Nostoc sp. VICCR1-1 after harvesting, the most probable number-denaturing gradient gel electrophoresis technique using 16S rRNA gene was employed. The results indicated that the remaining population is at 2.5× 10 5 and 1.62×10 6 cells m −2 in treatments supplied with vegetative cells and akinete inocula, respectively. Akinete induction might be one of the appropriate approaches for producing cyanobacterial inoculum.

This study aimed to evaluate the γ-aminobutyric acid (GABA) production and antioxidant activity during fresh cheese processing with single and co-fermentation processes of the high-GABA producing strain, Lactobacillus plantarum L10-11. For a mini-batch of fresh cheese, milk with 0.1% monosodium glutamate was fermented for 18 h and GABA production was monitored by thin layer chromatography and ion chromatography. GABA could be detected in co-L10-11 at 12 h of fermentation and at greater amounts after 18 h. The 18 h fermented milk of co-L10-11 and single-L10-11 contained GABA at 11.30 and 1.21 mg/100 mL, respectively, while GABA was not detected in the control. After whey separation, GABA remained in the cheese curd portion, resulting in 14.91 mg/100 g being found in the co-L10-11 cheese curd. ABTS antioxidant and metal chelating activities significantly increased during 18 h of fermentation and were retained in the cheese curd in the range of 783.11-922.00 μmol TE/kg and 216.71-266.98 μmol EDTA equivalents/kg cheese, respectively. Moreover, there were no significant difference in the textural characteristic between co-L10-11 and the control cheese curd. These results suggested that Lb plantarum L10-11 could be exploited as adjunct to improve health-promoting effects of the GABA in fresh cheese.

Keywords: Denaturing gradient gel electrophoresis (DGGE), DNA dependent RNA polymerase (rpoC1), Microcystis viridis, rRNA intergenic spacer analysis (RISA), Terminal restriction fragment length polymorphism (T-RFLP) SummaryMicrocystis, which are toxic microcystin-producing cyanobacteria, normally bloom in summer and drop in numbers during the winter season in Senba Lake, Japan. Recently, this lake has been treated by ultrasonic radiation and jet circulation which were integrated with flushing with river water. This treatment was most likely sufficient for the destruction of cyanobacterial gas vacuoles. In order to confirm whether Microcystis viridis was still present, a molecular genetic monitoring technique on the basis of DNA direct extraction from the sediment was applied. Three primer sets were used for polymerase chain reaction (PCR) based on rRNA intergenic spacer analysis (RISA), the DNA dependent RNA polymerase (rpoC1) and a Microcystis sp.-specific rpoC1 fragment. The results from each primer were demonstrated on the basis of single strand conformation polymorphisms (SSCP). Using the RISA primer showed different results from the rpoC1 and Microcystis sp.-specific rpoC1 fragment; meanwhile, the rpoC1 Microcystis sp.-specific fragment was more specific than the RISA primer. Therefore, the Microcystis sp.-specific rpoC1 fragment was further analysed by denaturing gradient gel electrophoresis (DGGE). The DNA pattern representing M. viridis could not be detected in any of the sediment samples. However, the results were confirmed with another technique, terminal restriction fragment length polymorphisms (T-RFLP). Although T-RFLP patterns of 16S rDNA in sediment at 91 bp and 477 bp lengths were matched with the T-RFLP of M. viridis (HhaI and MspI endonuclease digestion, respectively), the T-RFLP pattern of 75 bp length was not matched with M. viridis (both of HhaI and MspI endonuclease digestion) which were the major T-RFLP pattern of M. viridis. Therefore, the results most likely indicated that M. viridis seems to have disappeared because of the addition of the ultrasonic radiation and jet circulation to the flushing treatment.

Although there are a number of raw milk collection centers in Nakhon Ratchasima, there is a lack of information with regard to the process of isolation and characterization of foodborne pathogens in raw milk. Therefore, the purpose of this research was to investigate the prevalence and characterization of foodborne pathogens, including Bacillus cereus, Escherichia coli, Listeria monocytogenes, Salmonella spp. and Staphylococcus aureus from 33 raw milk samples from 9 different raw milk collection centers located in 8 districts in Nakhon Ratchasima, Thailand. This study was conducted from January to March 2016. Results revealed that the contaminations of L. monocytogenes and Salmonella spp. were not detected in any of the raw milk samples tested. The prevalence of B. cereus, E. coli, and S. aureus in raw milk samples was found to be 9 % (10 - 2.0 ×104 CFU/ml), 42.4 and 54 % (85 - 2.7 ×104 CFU/ml), respectively. The distribution of virulence genes was tested in B. cereus and S. aureus using gene specific primers by polymerase chain reaction. Out of the 29 analyzed coagulase-positive S. aureus isolates, 27 isolates (93 %) were positive for eap gene amplification and 14 isolates (48 %) showed amplicon of eap gene and all 5 enterotoxin genes, including seG, seGV, seI, seIV, and seM genes. All 8 B. cereus isolates tested showed positive PCR result with enterotoxin FM (entFM) gene but they showed negative with hemolysin gene (hblA and hblD genes) amplifications. It was inferred from these findings that bulk tank milk is a potential source of S. aureus and B. cereus in milk.

No abstract