IntroductionPresenceof microorganisms in the wastewater treatment plants pays a major role in thetreatment process. According to ( Gerardi, 2007), the archaebacteriaand eubacteria are considered the mostimportant microorganisms in a biological Wastewater treatment plants. The twoprokaryotes are commonly referred to as bacteria. Wastewater treatment rolesattributed to bacteria include biologicalphosphorus removal, degradation of soluble CBOD, floc formation, andnitrification, denitrification, methanogens and fermentative processes.Zooglea Ramigera haslong been considered the typically activated sludge bacterium responsible forthe floc formation.
Itis capable of producing cellular components that enable flocs to “stick”together or agglutinate.Accordingto (Unz, 2017), since its discovery, Zooglea ramigera has been identified primarily from thecharacteristic tree-like Zooglea which are frequently observed in polluted environments.However, determination of its taxonomic position has been complicated due toinsufficient data in its physiology, biochemical and nutritional data toaccurately characterize and distinguish its species.
The generic name Zooglea originates from the Greek language meaning the “living glue'” because of its ability to attract nutrientsfrom the water. Based onthis description this organism obtained its name. Initially the only recognizedspecies of the genus Zooglea, Zooglea ramigera.This report, therefore, focuses on its morphological characteristics,metabolism, environment,relation with other organisms and its significance in society or in a specificecosystem that is relevant in water technology.
Morphological characteristicsZoogloea ramigera are extremelylarge, non-motile bacteria and can grow usually as “amorphous” clumps or”fingered” like a tree as shown in figure (1). These bacteria are arranged insharply demarcated columns or fingers which protrude from clusters. Its cells are straightto slightly curved rod-shaped and are nonspore forming bacteria (Dugan, Stoner, & Pickrum, 2006).Figure 1:Rod-shaped Zooglea ramigera(Adaptedfrom(Duganet al., 2006) Thisbacteria’s staining is Gram-negative(Friedman, Dugan, Pfister, & Remsen, 1968). They are Neissernegative. (Neisser positive turnspurple, while Neisser negative turns yellow).
With this feature they can bedifferentiated from filamentous. Zoogloea ramigera forms characteristic cell aggregates surrounded by gellatinousmatrices, the zoogloeal matrices. This matrix is composed of extracellular polymer strandsof polysaccharides(Friedman et al., 1968). The polysaccharide coating of Zoogleal bacteria is always high orexcessive, see figure (2) below. Figure 2: Zooglea ramigera clusters Figure 3: Excessive polysaccharide coating ofZooglea ramigera (www.EnvironmentalLeverage.com)EcosystemZoogloea ramigeralive freely in organically polluted fresh waters or waste water treatment , (Duganet al.
, 2006). Usually,its environment is characterized by a high food to mass ratio where there are readilybio-degradable soluble organic compounds such as wastewater. It can also can bein selector systems such as activated sludge(Williams & de los Reyes, 2006).
Figure 2: Habitat of Zooglea ramigera’s (Dugan et al., 2006)MetabolismStructureand composition of the zoogloeal matrix and consider it in relation tometabolic activities of the Zoogloearamigera (Madigan M; Martinko J, eds. ,2005).
It possesses an extremelyactive oxidative metabolism in the natural habitat. They are aerobic andchemoorganotrophic.Zoogloearamigera 1-16-M was found toZoogloea ramigera hasbeen found to contain two stereospecific acetoacetyl CoA reductases; 1)NADP+-linkedwith D-?-fi-hydroxybutyryl-CoA specific,2) NAD+-linked and L(+)-isomer specific(Saito, Fukui, Ikeda, Tanaka, & Tomita, 2000). The NADP +-linkedenzyme has a pH optimum for the reduction of acetoacetyl CoA at PH of 8.1, howeverfor the oxidation of hydroxybutyryl –CoA, optimum PH is non -definite.Zoogloeais not choosy nutritionally, thus a variety of organic carbon sources in asimple defined media may be used to culture it (Gerardi, 2007).Poly-?-hydroxybutyrate(PHB) is produced whenever both a carbon source is highly present as well asB-ketothiolase.
PHB synthesis and intracellular degradation is partiallycontrolled by NADPH and availability through glucose 6-phosphate dehydrogenase enzymewith optimum operating PH of 8.5 .The species is also known to use Mn-oxidationmetabolism because the matrix made by Zoogloea takes in and concentrated metalin water sources.Range forpH, temperature, salt concentrationThe preferred temperature for growth is 28-37degrees C. Zooglea ramigera flourishin an environment with a PH of 7.0-7.
5. The formation of flocs and films inliquid media at late stages of growth are distinguished by treelike orfingerlike morphology. Colonies on C4 agar, at 3-4 days, reach 1mm in diameterare circular, raised, & translucent with opaque centers of gray or white.Mature colonies are tenacious and cohesive and can be lifted from agar surfaceintact with a needle. Control of the environment for Zooglea ramigera can be achieved viaPH and temperature. Similar to itsmetabolic activities, the preferred temperature for growth is 28-37 degrees.
Zooglea ramigera flourish in anenvironment with a PH of 7.0-7.5 because a decrease in PH of the activatedsludge process favors the proliferation of filamentous fungi and disfavors thegrowth of bacteria(Angelbeck& Kirsch, 1969). Nutrient type, addition, andcontrol is usually recommended. Zoogleal bulking occurs when the bacteria takestoo long to access nutrients in an environment with high BOD loading ornutrient slug feeding rate is not consistent or when the nutrient is notsufficient.According to((Richard& Ph, 2003)) conditions that favor Zooglea orother microbes responsible for viscous bulking are: High levels of soluble organics in theinfluent and imbalance in macronutrient (C:N:P) favoring organisms that an uptake scarcenutrients such as Zooglea ramigera.