V 730 bio uv visible spectrophotometer

The total contents of phenolic compounds of the respective algae were found using a modified Folin–Ciocalteu method [25 (link)]. Briefly, the fresh algal bodies were freeze-dried before the experiment. The dried bodies (0.2 g) were powdered with a mixer. Then the powder (0.2 g) was extracted with 5 mL of 80% ethanol for 24 h at room temperature. After the supernatant was collected following shaking and centrifugation by 700× g for 10 min, the extract was stored at −10 °C until further analysis.
To 0.2 mL of the sample solution, we added 0.4 mL of 10% Folin–Ciocalteu phenol reagent. After 3 min, 0.8 mL of 10% sodium carbonate was added. The mixture was allowed to stand for 30 min. The absorbance was measured at 750 nm by V-730 BIO UV-visible spectrophotometer (JASCO International Co., Ltd., Tokyo, Japan). The phenolic compound contents are expressed as pirogallol equivalent.

The genomic DNA of M. xanthus was isolated with the QIAamp DNA Mini Kit (Qiagen, Hilden, Germany). The 5TA fragment was amplified from the myxovirescin A biosynthetic gene ta-1 of M. xanthus with the primer pair loTA Gib F/R. The vector pTA-Kan^R [32 (link)] was linearized by PCR using the primer pair ploTA F/R. The PCR products were purified via electrophoresis on 1% agarose gel followed by extraction from the gel using a FavorPrep GEL/PCR Purification Mini Kit (Favorgen Biotech Corp., Taiwan, China). The concentration of the DNA solutions was measured on a V-730BIO UV/visible spectrophotometer (JASCO, Tokyo, Japan). The DNA fragment “5TA” was assembled to the linearized vector using NEBuilder^® HiFi DNA Assembly Master Mix (NEW ENGLAND BioLabs Inc., Ipswich, MA, USA) at the DNA molar ratio of 3:1 (0.2 pmol in total) to generate the plasmid p5TA-Kan^R according to the manufacturer’s manual. A portion (2 µL) of the assembled product was transformed into Competent high DH5α (TOYOBO) according to the manufacturer’s manual. The resulting colonies were verified by PCR using the primer pair ploTA check F/R located at one end of the assembly site. The Red/ET recombination modification cassette 5TA-Kan^R was amplified by PCR using the assembled plasmid p5TA-Kan^R as the template.