Cultural and biochemical diversity of pink-pigmented bacteria isolated from paper mill slimes

A study of 25 paper mill slime deposits and one additive revealed nine pink-pigmented bacterial isolates, eight of which were different from pink-pigmented bacteria identified in the paper industry in the middle 1900s. The pink-pigmented bacteria described previously in pulp and paper included Micrococcus agilis, Bacillus subtilis, Serratia sp. and Alcaligenes viscosus. With the exception of one isolate, Micrococcus sp., these isolates possessed many cultural, biochemical and chemical properties which were different from the ones previously reported for paper mills. Eight of these bacteria were Gram-negative rods or filamentous, aerobic and positive for catalase production. Two isolates were methylotrophic, oxidizing methanol and identified as Methylobacterium zatmanii. Cellular fatty acid analysis and other characteristics showed one isolate to be Roseomonas sp. Using 16S rRNA gene sequencing, one isolate which was a Gram-negative rod was identified as Deionococcus grandis. Four bacteria had cells that were long or filamentous and these were isolated from mills with pink slime problems. The identity of one of the filamentous bacteria was determined by 16S rRNA gene sequencing to be close to Flectobacillus sp. strain MWH38. Most of the isolates were susceptible to 11 industrial biocides. Journal of Industrial Microbiology & Biotechnology (2000) 25, 74–80. Received 28 January 2000/ Accepted in revised form 09 June 2000