Secies Composition of Sulfur Oxidizing and Denitrifying Bacteria from the Tannery Wastewater Treatment Plant, Modjo, Ethiopia
No Thumbnail Available
Date
2000-03
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Ababa Universty
Abstract
The discharge of tannery effluents to different water bodies increase pollution because of heavy
accumulation of toxic compounds such as sulfur and nitrogen containing organic wastes, chromium,
arsenic etc. Thitty-six strains of Sulfur Oxidizing Bacteria (SOB) belonging to sixteen genera were
isolated fi'om the three tannery ponds of a Tannery Waste Treatment system at Modjo. They were
characterized on the basis of their cultural, morphological, and physiological characters. The genera
were Acidiphilium, Acromatium, Macromonas, Sulfolobus, Thermothrix, Thiobacilllls, Thiobacterium,
Thiomicrospira, Thiosphaera, Thiospira, Thiovullim Rhodobacfor, Rhodocyclus, Rhodomicrobillm,
Rhodopseudomonas, and Rhodosprillllm. Out of these isolates, twenty-one strains falling into twelve
genera were capable of denitrification. Bacterial enumeration based on MPN technique showed a
population number between 1.2 x 103 and 1.1 x 106
. The number of strains recovered from the different
ponds varies such that twenty, sixteen, and nine strains were isolated fi'om AFP, SFP, and MP,
respectively. The dominant strains isolated from different pond systems were the genera Thiobacilllls (S
strains), Rhodopselldomonas, (4 strains), and Rhodomicrobiulll (3 strains). The most frequently isolated
strains in the three different pond systems were Thiobacilllls (AUS9) and Rhodolllicl'obilllll (AU142).
Isolated strains showed variation in growth on different media and some such as Acidiphiliulll (AUS);
Slilfoloblis (AUl2); Thiobacillus (AUS9) Thiolllicrospira (AU62); Thiosphaera (AUS7)
Rhodolllicl'obilllll (AUl42, AU164, AUl76) failed to grow on denitrifYing medium but were capable of
growing on nitrogen free (nit) medium. Most of the isolates were found to be slow growers reaching to
their exponential stage between 4S-72 hours. In their spatial distribution, the anaerobic strains in AFP
system and the aerobic isolates in the SFP and MP systems were found to be dominant.
Description
Keywords
Oxidizing and Denitrifying Bacteria