Microorganisms, including those living in sea water, are a rich source of various organic compounds. Nocardia sp. isolated from residues of marine macrophytes of the Sea of Japan was growing in a culture medium, where substance (I) was detected. Substance (I) was obtained as an amorphous powder by column chromatography on Sephadex G-25 and silica gel (eluent: chloroform-ethanol-water = 10:10:1) and purified by high-performance liquid chromatography on Whatman ODS columns (eluent: water). UV, mass, ¹H NMR, and ¹³C NMR spectra were used for analysis. Methylation of (I) with diazomethane yielded dimethyl derivative (II), and decarboxylation of the Na salt of (I) at 300-350°C gave hydroxypyridine (III). The hydroxy group position was determined by comparing (III)'s UV spectrum with literature, and the carboxy group position by analyzing (I) and (II)'s ¹H NMR spectra. Atomic absorption spectrometry showed Na content (14.2%, calculated for C₆H₄NO₃Na: 14.0%). Thus, (I) was identified as the Na salt of 5-hydroxypicolinic acid. To our knowledge, a hydroxypicolinic acid has not previously been described in a microorganism's culture medium. Additionally, pears are rich in free amino acids; 16 of 20 common amino acids (7 essential) were identified in two pear varieties, and amino acid changes during 50-day storage were studied via 85% ethanol extraction from skin and flesh.