Biofilm characteristics and evaluation of the sanitation procedures of thermophilic Aeribacillus pallidus E334 biofilms

The ability of Aeribacillus pallidus E334 to produce pellicle and form a biofilm was studied. Optimal biofilm formation occurred at 60 °C, pH 7.5 and 1.5% NaCl. Extra polymeric substances (EPS) were composed of proteins and eDNA (21.4 kb). E334 formed biofilm on many surfaces, but mostly preferred polypropylene and glass. Using CLSM analysis, the network-like structure of the EPS was observed. The A. pallidus biofilm had a novel eDNA content. DNaseI susceptibility (86.8% removal) of eDNA revealed its importance in mature biofilms, but the purified eDNA was resistant to DNaseI, probably due to its extended folding outside the matrix. Among 15 cleaning agents, biofilms could be removed with alkaline protease and sodium dodecyl sulphate (SDS). The removal of cells from polypropylene and biomass on glass was achieved with combined SDS/alkaline protease treatment. Strong A. pallidus biofilms could cause risks for industrial processes and abiotic surfaces must be taken into consideration in terms of sanitation procedures.

Anoxybacillus salavatliensis sp. nov., an α-glucosidase producing, thermophilic bacterium isolated from Salavatli, Turkey

A novel moderately thermophilic, Gram-positive staining, rod-shaped, spore-forming, motile, facultative anaerobic, and α-glucosidase producing strain A343(T), was isolated from a high temperature well-pipeline sediment sample in Salavatli province of Aydin, Turkey. Growth was observed at 37-69 ºC (optimum 60 °C), at pH 5.5-9.5 (optimum 8.0-9.0) and at salinities from 0 to 4.5% (w/v) (optimum 2%). Strain A343(T) was able to grow on a wide range of carbon sources. Gelatin and starch utilization, amylase, catalase and oxidase activities, reduction of nitrate to nitrite were all positive. The G+C content of the genomic DNA was 45.1 mol%. The major menaquinone was MK-7. The dominant cellular fatty acids were: iso-C15:0, C16:0, and iso-C17:0. The phylogenetic analysis based on the 16S rRNA gene sequence revealed that the strain A343(T) belonged to the genus Anoxybacillus. The 16S rRNA gene sequence similarity between strain A343(T) and the type strains of recognized Anoxybacillus species was ranged from 95.8 to 99.4%. DNA-DNA hybridization revealed low homology with its closest relative Anoxybacillus kamchatkensis (49.7%). In addition to the total cell protein profiles, the Rep-PCR and the intergenic 16S-23S rRNA gene fingerprinting profiles differentiated strain A343(T) from all of the reference Anoxybacillus species used. Based upon phenotypic, phylogenetic and chemotaxonomic evidence, strain A343(T) was assigned to a new species within the genus Anoxybacillus, A. salavatliensis sp. nov. (The type strain A343(T) = DSM 22626(T) = NCIMB 14579(T)). The 16S rRNA gene nucleotide sequence of strain A343(T) is available in the GenBank database under the accession number--EU326496. Weinheim).