Isolation and characterization of filamentous bacteria from paper mill slimes

The composition of filamentous bacteria in paper machine systems has received little scientific scrutiny, even though these organisms have been associated with many problems that affect machine efficiency and paper quality. The objective of the study was to isolate and characterize filamentous bacteria in paper mill slimes using conventional microbiological techniques, fatty acid methyl ester (FAME) analysis, and 16S rRNA gene sequencing. Filamentous or long, thread-like bacteria from different genera were observed. Pink or red-pigmented filamentous bacteria identified as Flectobacillus sp. were commonly isolated from pink slime deposits, but they were also obtained from deposits that did not appear pink or red. Two organisms had certain characteristics that were different from similar organisms previously described. One was a Gram-negative, filamentous bacterium with golden yellow colonies. This organism was esculin positive, and hydrolyzed starch but did not produce hydrogen sulfide. A BLAST search of GenBank database produced an identity of 92% with Cytophaga sp. or Flavobacterium columnare. A Gram-positive bacterium that produced very long or filamentous structures was also observed. On tryptic soy agar, this organism produced yellow colonies, but on plate count agar, the colonies were white. The plate count agar-grown cells were atypical with many of them having bulbs either in the middle or at the ends of the cell. In indole nitrite broth, the organism produced a very extensive filamentous structure. The FAME and 16S rRNA gene analyses of this organism showed that the organism was a Bacillus sp., but no spores were produced in any of the media studied, including a sporulating medium. Various spore-formers, identified as Bacillus psychrophilus and Paenibacillus sp., also had long continuous chains of cells. Two species of Chryseobacterium produced long filaments. Actinomycetes with branched mycelia and identified as Norcardiopsis alba and Streptomyces albidoflavus were isolated from wet lap pulp samples. These actinomycetes produced a very strong earthy odor both in culture and in field samples. Information, such as growth requirements and presence or absence of endospores, gained about these organisms will help in their control. (C) 2002 David Oppong. Published by Elsevier Ltd. All rights reserved.