Figure 1: Bi-weekly Degradation Rate of crude oil by Aspergillus flavipes as shown by Gravimetry
Code |
Colony morphology |
Microscopy |
Identity |
UBA |
Colonies on SDAwere dark green with yellowish tint, with cushion-shaped structures distributed.Needle-shaped crystals were characteristically formed in cultures. Reverse side was tan |
Conidiophores were hyaline, erect, branched, bearingspore masses apically at verticillate phialides: phialides were short andthick. Conidia werephialosporous, hyaline, globose, subglobose, or ovate, one-celled. Chlamydospores were brown and subglobose. |
Trichoderma sp |
UBD |
On SDA, colonies were floccose (cottony in texture), pale greyish-brown. Growth rate was rapid, thus, colonies filled the entire petri-dish in 3 days. Colour on the reverse side was yellow. Colonies were incubated at 30 oC for 5 days. |
Sporangiophores were hyaline, erect, non-septate and branched sympodially and circinate. Sporangia were terminal,dark-brown, finely echinulate to smooth and spherical (20- 80 µm in diameter). Sporangiospores were hyaline or pale-brown. Collumellae were ellipsoidal and 4.5-7 x3.5-5 µm in size. Chlamydospores were absent. |
Mucor sp |
UBE |
On SDA colonies displayed moderately slow growth on at 30ᵒC. texture is velutinous (soft, velvety surface) to floccose (woolly tufts of soft “hairs”). The colonial growth appeared radially sulcate (narrow, deep furrows or radial grooves –like spokes on a wheel). The mature colony had a central greyish-turquoise to greyish-orange colour with a white periphery (outer edge). Exudates (extrolites) were frequently produced which appeared as drops of liquid upon the surface of the colony, which appeared to be clear, to pale yellow, to reddish-brown in colour. The reverse was a pale yellow to a light yellow-brown. |
Organism produced septate, hyaline (clear, not pigmented) hyphae. Smooth-walled conidiophores stipes were rather long (100 – 300 µm) and is biverticillate. Metulae were 12 – 15 µm in length which were found in whorls of 3 – 5 divergent structures. Phialides were ampuliform (flask-shaped) and about 7 – 12 µm in length. Conidia (2.2 – 3.0 µm diameter) were globose to sub-globose (round to off-round) and were smooth or had a finely roughened surface. Conidia resist disruption and formed rather long chains. These characteristics: the metulae longer than the phialides and the conidia being both spherical and produced in well-defined chains, were distinguishing features of Penicilliumcitrinum. |
Penicillium citrinum |
OKA |
On SDA organisms were dull white to yellow to light yellow. Dark fluorescent yellow colour was observed on the reverse side. No sclerotia were observed and growth rate was good. |
Conidiophore length was 403-521 µm, breadth 7.3-8.7 µm. conidiophores were yellowish to pale brown and coarsely roughened. Conidiospore size was 2.5-2.7 µm, ellipsoid, smooth to finely roughened. Vesicle diameter is 20-24 µm. phialides are biseriate, 7-8 µm in length and and 2.2-2.4 µm in diameter. |
Aspergillus Ochraceus |
OKC |
On SDA, colonies were green with with white margins. The reverse side was cream to light cream-brown. Good growth rate observed.Coonial texture was velvety to floccose |
Conidiophores are echinulate/colourless. Vesicle is globose and covered by biseriate phialides with globose echinulate conidia.sclerotia were dark and bullet shaped, conidia were subglobose/ellipsoidalwith fine rough walls. |
Aspergillus nomius |
UA |
On SDA, colonies were slow growing, with dense aerial mycelium, initially greenish-grey, later becoming dark brown to grey-brown |
Hyphae were septate, pigmented, and irregularly shaped, with swollen segments up to 4 μm in diameter. |
Microsphaeropsisarundinis |
UB |
Colonies on SDA agar are velvety, pale grayish green on the surface. The colour on the reverse side is pale yellowish brown. Growth rate: 2–3 cm in diameter in 10 days after incubation at room temperature |
Conidiophores hyaline, erect, branched penicillately at the apexes with verticillate metula, terminal phialides and catenulate conidia on each phialide, forming rather divergent conidial heads: phialides pen-pointed with abruptly tapered tips. Conidia phialosporous, pale green, dark in mass, ellipsoidal or subglobose, 1-celled, smooth, apiculate at one end. |
Penicillium janthinellum |
UC |
On SDA,growth was moderately rapid and matured within 7 days of incubation. The colony diameter was 1-3 cm following incubation at 25°C for 7 days. Colonies were flat, smooth, resupinate, moist, yeast-like, mucoid to pasty, shiny and leathery in appearance. The surface was white, pale pink or yellow at the beginning and became brown to black and velvety with a grayish fringe by aging. Reverse was pale or black. |
Blastoconidia were pale in color. Synchronous development of blastoconidia in tufts was observed. Hyphae were septate appearing hyaline at the beginning and getting dark brown by aging. The width of the hyphae was 2-10 µm but may be as thick as 15-20 µm. Conidiogenous cells, which were not much differentiated, were either intercalary or located terminally in the hyphae. The conidia (4-6 x 2-3 µm in size) were one-celled, hyaline and oval to cylindrical in shape. They formed clusters or were located along the hyphae. Blastoconidia, chlamydoconidia and arthroconidia may also be observed. Thick-walled, one- to two-celled, phaeoid arthroconidia were produced in old, mature cultures. |
Aureobasidiumsp |
OA |
On SDA, green mycelium with yellowish, dull buff, aerial brownish with age. Slow growing colonies were observed. Reverse was orange-brown to red |
Largely tightly packed conidia chains were observed Vesicles were subglobose to elliptical, up to 30 by 40 µm in the largest forms, usually with diametertwice that of the conidiophore in smaller forms. Sterigmata were in two series,colourless or nearly so, closely packed over the apex of the vesicle in smallheads, and covering the vesicle in large heads, primary sterigmata about6 or 8 µm by 2 to 3 µm, secondary sterigmata 5 to 8 µm by 1.5 to 2 µm. Conidia were 2to 3 µm, smooth, subglobose, colorless or nearly so under high magnification,with chains aggregated to form columns as seen with a handlens in oldcultures. |
Aspergillus flavipes |
OD |
On SDA, Growth rate was moderate. Colour was blue-green to dark green to greyish-turquoise. Reverse was maroon to reddish-brown. Texture was as lanose(woolly) and velutinous (dense, silky hairy). Colonies produced rather long conidiophore stipes approximately up to 200 µm which gave the colony that woolly or hairy appearance. |
The long, smooth-walled stipes which bore the conidiophores were hyaline generally (translucent/colourless) or slightly brownish. The vesicles (7.0 µm - 17 µm wide) were sub-spherical, pyriform (pear or teardrop shaped) to somewhat clavate (club shaped). Conidiogenous structures were biserate with metulae (2 µm -3.5 µm by 4 µm -6 µm) and phialides (2 µm – 3 µm by 5 µm – 7 µm) in size. Diminutive conidial structures were produced by many isolates which may resemble penicillate (likePenicillium) heads. Conidia were spherical, echinulate or spinose (rough, jagged texture), and were about 2.5 µm to 4.0 µm in diameter. Hülle cells were also present. |
Aspergillus sydowi |
UE |
Cultures on SDA were fluffy, bright yellowish green with bluish green tint, funiculose with bundles of hyphae, reverse yellowish pink with reddish purple tint. Rather good in growth. |
Conidiophores were hyaline, erect, developed from aerial hyphae, branched penicillately at the apexes with primary and secondary metula. verticillate phialides and catenulate conidia in each phialide, were seenwith open-spaced yellowish green conidial heads: phialides lanceolate or abruptly sharpened. Conidia werephialosporous, pale green, dark in mass, globose to subglobose, one-celled, minutely echinulate on the surface. |
Penicillium sp |
OKB |
On SDA, colonies are fast growing, black to olivaceous-black or greyish, and are suede-like to floccose. Reverse was brown-black on reverse due to pigment production |
Microscopically, branched acropetal chains (blastocatenate) of multicellular conidia (dictyoconidia) were produced sympodially fromsimple, sometimes branched, short or elongate conidiophores. conidia are obclavate, obpyriform, ovoid to ellipsoidal, often with a short conical or cylindrical beak, pale brown, smooth-walled and/or verrucose. Alternaria produces the pigment melanin therefore structures appeared brown to black in colour with dark septate hyphae |
Alternaria sp |
OB |
On SDA, colonies were powdery, flat, white at first, then turned yellowish-brown with age. Colour on the reverse side was yellow. Colonies were incubated at 30 oC for 5 days |
Conidiophores appeared blue and terminated in a vesicle of uniseriate phialides. Conidia were one-celled, rough-walled and produced in long chains which were divergent. |
Aspergillus sp |
OKPb |
On SDA, the growth rate was moderately good at room temperature and the texture was velvety to powdery. The colour was olivaceous green to black from the front and black from the reverse. |
Conidia were elliptical to cylindrical in shape, pale to dark brown in colour and have dark hila. They occurred in branching chains that readily disarticulate. Conidial wall was smooth or occasionally echinulate. They produced unicellular conidia. |
Cladosporium sp |
Table 1: Phenotypic and Genotypic Characteristics of Fungal Isolates from Uburu and Okposi Salt Lakes
Slight Halophiles (1-5% Salt) |
Moderate Halophiles (5-20% Salt) |
Borderline Extreme Halophiles (9-23% Salt) |
Extreme Halophiles (15-30% Salt) |
|
Cladosporium sp. (7mm at 15%) |
Penicillium sp(20mm at 20%), |
Aspergillus flavipes (13mm at 40%) |
|
|
|
Penicilliumcitrinum (10mm at 40%) |
|
|
|
Aspergillus ochraceus(9mm at 40%) |
|
|
|
Aspergillus nomius(15mm at 35%) |
|
|
|
Microsphaeropsisarundinis(12mm at 35%) |
|
|
|
Aspergillus sydowi(28mm at 30%) |
|
|
|
Penicillium janthinellum(26mm at 30%) |
|
|
|
Mucor sp(13mm at 30%) |
|
|
|
Aureobasidiumsp(12mm at 30%) |
|
|
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Trichoderma sp (9mm at 30%) |
|
|
|
Alternaria sp. (22mm at 25%) |
|
|
|
Aspergillus sp (18mm at 25%) |
Table 2: Halophilic Classification of Isolates
Samples |
No. of colonies on plate |
Total fungal count(CFU/ml) 10-2 |
2% crude oil + Bushnell-Haas broth |
256 |
2.56x105 |
4% crude oil + Bushnell-Haas broth |
TFTC |
TFTC |
6% crude oil + Bushnell-Haas broth |
TFTC |
TFTC |
Table 3: Growth Tolerance of Aspergillusflavipes on different Percentages of Crude Oil
Tables at a glance
Figures at a glance