(EP615998-A2)      A 2,4-polybenzooxazole having repeating units of formula (I) is new:    Pref. (I) is a homopolymer, or a copolymer with 3-amino-4-hydroxybenzoic acid, 4-amino-3-hydroxybenzoic acid or 2,3-diaminobenzoic acid.    A precursor cpd. 2,3-dihydro-3-hydroxyanthranilic acid (DHAA), is prepd. by aerobically fermenting an aq. nutrient medium with a mutant strain of microorganisms of the species Streptomyces aureofaciens, (Sa-652) by a method similar to that of US3038005. The spores are grown via Sa-652 at 28 deg.C and pH 6.8 on a vegetative medium comprising sucrose, corn sepp liquor and ammonium sulphate, to produce a vegetative inoculum. The fermentation medium contains sucrose, corn steep liquor or solids, soybean meal, carboxymethylcellulose, ammonium sulphate and chloride, Fe-, Mn- and Zn- sulphates, Co chloride and sigma antifoam B, at a pH of 6.5-7.1, a temp. of 25-37 deg.C and an agitation speed of 400 rpm. The conversion of DHAA to the AB monomer 3-hydroxyanthranilic acid (HAA) is effected by dehydrogenation in the presence of a Pd or C catalyst, opt. without isolation of pure DHAA from the fermentation broth.    The prepn. of 2,4-polybenzooxazole polymers is carried out by thermal (co)polymerisation or soln. (co)polymerisation in polyphosphoric acid using a P205 adjustment method.    USE/ADVANTAGE -   Used to prepare thermally stable, transparent coatings for solar cells that inhibit ionising radiation, and in blends as reinforcements in molecular composite technology. The polybenzoxazoles are produced by an inexpensive biochemical or biosynthetic route from renewable feed-stock nutrients. They possess high modulus and high strength properties and are environmentally resistant.    (JP7309946-A)      A 2,4-polybenzooxazole having repeating units of formula (I) is new:    Pref. (I) is a homopolymer, or a copolymer with 3-amino-4-hydroxybenzoic acid, 4-amino-3-hydroxybenzoic acid or 2,3-diaminobenzoic acid.    A precursor cpd. 2,3-dihydro-3-hydroxyanthranilic acid (DHAA), is prepd. by aerobically fermenting an aq. nutrient medium with a mutant strain of microorganisms of the species Streptomyces aureofaciens, (Sa-652) by a method similar to that of US3038005. The spores are grown via Sa-652 at 28 deg.C and pH 6.8 on a vegetative medium comprising sucrose, corn sepp liquor and ammonium sulphate, to produce a vegetative inoculum. The fermentation medium contains sucrose, corn steep liquor or solids, soybean meal, carboxymethylcellulose, ammonium sulphate and chloride, Fe-, Mn- and Zn- sulphates, Co chloride and sigma antifoam B, at a pH of 6.5-7.1, a temp. of 25-37 deg.C and an agitation speed of 400 rpm. The conversion of DHAA to the AB monomer 3-hydroxyanthranilic acid (HAA) is effected by dehydrogenation in the presence of a Pd or C catalyst, opt. without isolation of pure DHAA from the fermentation broth.    The prepn. of 2,4-polybenzooxazole polymers is carried out by thermal (co)polymerisation or soln. (co)polymerisation in polyphosphoric acid using a P205 adjustment method.    USE/ADVANTAGE -   Used to prepare thermally stable, transparent coatings for solar cells that inhibit ionising radiation, and in blends as reinforcements in molecular composite technology. The polybenzoxazoles are produced by an inexpensive biochemical or biosynthetic route from renewable feed-stock nutrients. They possess high modulus and high strength properties and are environmentally resistant.