Ecophysiology and molecular phylogeny of bacteria isolated from alkaline two-phase olive mill wastes.
The use of two-phase centrifugal decanters has been widely adopted in the olive oil extraction industry in order to reduce the huge quantities of wastewaters produced during the traditional three-phase extraction process. The resulting sludge-like byproduct, widely known as "alpeorujo", has a pH of 4-6, low water activity (a(w)) and high phytotoxicity. Addition of Ca(OH)(2) to alpeorujo, which is commonly performed at the olive oil mill to handle disposal problems related to acidic pH and odor emissions, creates an alkaline secondary waste (alkaline alpeorujo). Bacteria isolated from alkaline alpeorujo were cultured in order to investigate their physiological and phylogenetic characteristics. The bacterial population at neutral pH was estimated to be 6.0+/-0.4 x 10(7) cells g(-1) dw, while the bacterial population at pH 11 reached 2.1+/-0.3 x 10(5) cells g(-1) dw. Fourteen strains isolated from alkaline pH were halotolerant alkaliphiles, while seven isolates from neutral pH were moderate to extreme halotolerant or/and alkalitolerant bacteria. Based on 16S rRNA gene sequence analysis, four of the halotolerant alkaliphilic isolates showed 98.4-99.2% similarity to known sequences of Bacillus alcalophilus and Nesterenkonia lacusekhoensis, whereas ten isolates demonstrated low percentage similarities (94.4-96.9%) to the genera Idiomarina, Halomonas and Nesterenkonia. As concerns bacteria isolated from neutral pH, four isolates were associated with Corynebacterium, Novosphingobium, Serratia marcescens and Pseudomonas aeruginosa (98.3-99.9% similarities), while three isolates presented 96.5-97.2% sequence similarities to Rhodobacter, Pseudomonas and Ochrobactrum. At least six groups of isolates represent novel phylogenetic linkages among Bacteria.
Ntougias
Spyridon
S
Institute of Environmental Biotechnology, National Agricultural Research Foundation, Lakonikis 87, 24100 Kalamata, Greece. sntougias@in.gr
Zervakis
Georgios I
GI
Ehaliotis
Constantinos
C
Kavroulakis
Nektarios
N
Papadopoulou
Kalliope K
KK
D001419:Bacteria / Q000145:classification* / Q000235:genetics / Q000378:metabolism; D002126:Calcium Hydroxide; D004783:Environmental Microbiology; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste / Q000032:analysis*; D000069463:Olive Oil; D010636:Phenols / Q000378:metabolism; D010802:Phylogeny; D010938:Plant Oils / Q000737:chemistry*; D012336:RNA, Ribosomal, 16S / Q000235:genetics
D007220:Industrial Waste; D000069463:Olive Oil; D010636:Phenols; D010938:Plant Oils; D012336:RNA, Ribosomal, 16S; D002126:Calcium Hydroxide