The iron requirement of four strains of lactobacilli (L. acidophilus, L. delbrueckii subsp. bulgaricus, L. plantarum, and L. pentosus) was studied in a synthetic medium under aerobic or anaerobic conditions. Effects of iron salt and iron-chelated compounds were tested on bacterial growth in manganese-free or -supplemented media. No significant growth stimulation was observed in any condition. These results support the absolute manganese requirement for optimum growth of lactobacilli and the needless incorporation of iron in growth media.

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Pseudomonas maltophilia has been identified in the rhizosphere of several cultured plants: cabbage, rape, mustard, corn, beet. In comparison with nonrhizospheric soil, all the rhizospheric samples analysed contain more of this Pseudomonas and the most important stimulation is supplied by cruciferous plants. The possible relation with greater amounts of sulphur-containing amino acids in root secretion is suggested.

Aims: Knowledge on factors of Aeromonas caviae promoting the formation of biofilms on surfaces. Methods and Results: In nutrient broth under agitation, A. caviae LMG 13455 was able to form biofilms on the surfaces of glass flasks, but such biofilm formation was inconsistent. A derivative of this strain, called M12, promoted the rapid formation of reliable and strongly adherent biofilms with about half of the cells being adhered. In contrast with its parent, M12 was hydrophobic, displayed auto-aggregation in liquid medium, synthesized very little polysaccharides and was defective in swimming and swarming motilities, together with the appearence of a characteristic phenotype on motility soft agar. Further analyses demonstrated that most of these properties were related to a hyperpiliation of the cells through the presence of type IV pili, and suggested that a mechanism of genetic variation, by altering the nature of motility appendages, allows the variant bacteria to attach on inert surfaces. Conclusions: M12 is a stabilized variant of the parental strain, promoting strongly adherent biofilms through the type IV pili. Significance and Impact of the Study: The wild-type strain A. caviae LMG 13455 include subpopulations that are likely implicated in its adaptation to different environmental changes.

Biodegradation of natural and synthetic (melanoidin) humic acids by Phanerochaete chrysosporium BKM-F 1767 was demonstrated by decolorization in batch culture, reduction in molecular weight, and '4Co2 production from labeled melanoidin. This biodegradation occurred during secondary metabolism of the fungus in nitrogen-limited cultures; experimental results suggest that all or a part of the lignin-degrading system of BKM-F 1767 plays a part in biodegradation.