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Foxing of paper is a deterioration phenomenon occurring in the form of brown-yellowish spots, the abiotic and/or biotic causes of which are not yet completely understood. Nevertheless, microbiological infection has been recognized that may contribute to paper damage and therefore it becomes important to know the taxonomic position and the degradative activity of the potential infectious biological agents which mostly are fungi, but also bacteria and yeasts. A cellulolytic bacterial strain isolated from a foxed paper sample exhibited morphological and physiological characteristics of the Bacillus genus. To study its taxonomic position, different identification methods were used: the Biolog system, the direct amplified polymorphic DNA-polymerase chain reaction analysis (DAPD-PCR) and the partial sequencing of the 16S rDNA gene. Biolog system and partial sequencing of 16S rDNA gene assigned the strain to the Paenibacillus polymyxa species. DAPD-PCR analysis indicated a high similarity with Bacillus circulans, by comparing the isolated strain with some closely related Bacillus species.

The organochlorine pesticide γ-hexachlorocyclohexane (γ-HCH, lindane) and its non-insecticidal isomers α-, β-, and δ- continue to pose serious environmental and health concerns, although their use has been restricted or completely banned for decades. The present study reports the first results on the ability of two Arthrobacter strains, not directly isolated from a HCH-polluted site, to grow in a mineral salt medium containing α-, β-, or γ-HCH (100 mgl(-1)) as sole source of carbon. Growth of cultures and HCHs degradation by Arthrobacter fluorescens and Arthrobacter giacomelloi were investigated after 1, 2, 3, 4, and 7 days of incubation by enumerating colony forming units and GC with ECD detection, respectively. Both bacteria are able to metabolize the HCHs: A. giacomelloi is the most effective one, as after 72 h of incubation it produces 88 % degradation of α-, 60 % of β-, and 56 % of γ-HCH. The formation of possible persistent compounds was studied by GC/MS and by HPLC analysis. Pentachlorocyclohexenes and tetrachlorocyclohexenes have been detected as metabolites, which are almost completely eliminated after 72 h of incubation, while no phenolic compounds were found.

Growth, acetylene reduction, and respiration rate were studied in batch and continuous cultures of Arthrobacter fluorescents at different oxygen partial pressures. The optimum pO2 values for growth and acetylene reduction were 0.05 and 0.025 atm, respectively, but microorganisms can tolerate higher pO2 values. The growth of cultures provided with combined nitrogen was dependent on oxygen availability, and strict anaerobic conditions did not support growth. Acetylene reduction of a population grown in continuous culture and adapted to low pO2 (0.02 atm) was much more sensitive to oxygenation than that of a population adapted to high pO2 (0.4 atm). Their maximum nitrogenase activity, at their optimal pO2 values, were quite different. The respiratory activity of nitrogen-fixing cultures increased with increasing oxygen tensions until a pO2 of 0.2 atm. At higher pO2 values, the respiration rate began to decrease.