Hexavalent chromium is resistant to degradation and sever toxic substance to environment and community health.

Overview

This source page is a mechanical bulk-ingest record for a PDF in the methylmercury infant-formula research pull. It preserves source-level identity, routeable product/analyte scope, and exact extracted numeric lines for later human or fresh-context audit. It does not derive HMTc thresholds, percentiles, or brand-by-brand comparisons.

Key numbers

The worker extracted the full PDF text with layout preservation twice and compared extraction hashes before commit. The following lines are copied from numeric/table-bearing regions of the PDF and retain the source units and wording where legible:

• License:   This work is licensed under a Creative Commons Attribution 4.0 International License. Read Full License
• utilization and chemical sensitivity test. The result revealed that 11 yeast species was identified from effluent waste
• and farm soil based on their probability >75% and similarity index >0.5 as well as their hexavalent chromium tolerance
• ability up to 2500ppm. These are Yarrowia lipolytica (100%,0.7) Cryptococcus luteolus(100%,0.64), Rhodotorula
• aurantiaca A (100%,0.62), Ustilago maydis (100%,0.58) Trichosporon beigelii B (100%,0.51),Cryptococcus terreus A
• (100%,0.62), Zygosaccharomyces bailii (98%,0.65), Nadsoniafulvenscens (90%,0.62), Schizoblastosporon starkeyi
• henricii (89%,0.56), Endomycopsis vivi (84%,0.62), Rhodotorula pustula (Sim 0.59). Two yeast species Yarrowia
• lipolytica and Nadsonia fulvenscens show the highest mean Optical density (OD) measure (0.953+0.43), (0.96+0.400)
• respectively at pH4 &25OC. Cr (VI)-tolerance ability of these yeast strains used after further HPLC analysis& molecular
• waste (Nakkeeran et al., 2018; Lian et al., 2019). Those industries built near the river side in Addis Ababa and different
• irrigating of the urban vegetable farming activities in Addis Ababa and neighboring area. CSA (2017) reported that
• chemical contamination in water bodies are very high where about 13% are estimated to be water free from chemical
• contamination. Cr+ 6 is water soluble and highly mobile which is bio-available in all environment therefore farmlands,
• 2020). The accumulation of potentially toxic elements(PTEs) in the environment and on the edible parts of vegetables
• with high concentrations could have a direct impact on the community health (Aschale et al., 2019).The primary health
• reproductive and developmental problems and death (Chatterjee,2015). According to the U.S. Environmental Protection
• human carcinogen (Dhal et al. 2013).
• When the concentration of Cr(VI) reach 5 to 100mg kg− 1in the soil, it is very toxic to most plants, as the result of Cr6+
• 2012). Different study carried out in Ethiopia where the level of heavy metal in farmland, water body and vegetables are
• vegetable farming area the level of chromium and other heavy metal are very high (Ewers 1991; Kabata-Pendias and
• Pendias 1992; Weldegebriel et al., 2012). Other studies reaffirmed that Akaki river was highly contaminated because of
• (Aregawi, 2014, Amare, 2019). In another study the physicochemical analysis of effluents from Sabata river and
• industries around Addis Ababa showed that beyond the safe limits of World Health Organization (Gemeda et al.,2020).
• 2355 meters above sea level. Some of the soil sample was collected from part of Rift valley at geographic coordinate
• 10g of soil from vegetable farm and 10mL wastewater samples from effluent waste was collected and kept in sterilized
• falcon tube (45mL) from Addis Ababa urban farming site, polluted rivers, effluent outlets and rift valley area. Totally
• 150 sample were collected. Sampling point were clustered depending on vegetable types and polluted rivers, these
• and 10gram of soil from each farm and effluent were taken. A total of 150gram soil were kept in 500mL Erlenmeyer
• flask 300mL distil water and 100mL potassium dichromate(K2Cr2O7) solution (500-2500ppm) were added within 3
• source of hexavalent chromium and kept at rotary shaker at 150rpm for 15days.
• After 15days from enriched soil sample & effluent, 10mL was transferred into 90 mL distil water and 1 mL
• subsequently transferred into 9mL distils water containing test tube. Serial dilution was prepared from 10-1 to 10-6mL.
• From each test tube using micropipette 0.1mL diluted sample were spread on potato dextrose agar (PDA) aseptically &
• isolates cultures will be maintained in PDA slant agar and kept at 4oC until further analysis employed.
• The interactions of three independent variables: temperature (25oC, 30oC, and 35oC), pH (values 4, 7, and 9) and
• hexavalent chromium concentration (500 ppm, 1000 ppm and 1500 ppm, 2000ppm, 2500ppm) were investigated using
• PDA media was amended with different concentration of K2Cr2O7 ranging from 500-2500 ppm and evaluated at
• different pH (4, 7 and 9) and Temperature range (150C, 250C, 350C) A loop full of fresh yeast isolates was transferred
• to this growth mediaand incubated at 260C for 48–72 hours. The plates were observed visually for any yeast colony
• 100mL Potato dextrose broth (PDB) in 250mL Erlenmeyer flask was amended by 500,1000,1500,2000, 2500ppm
• K2Cr207 and antibiotic. Each PDB concentration was adjusted at pH (4, 7 and 9) and Temperature (15OC, 250C, &35oC).
• 1ml of yeast culture 1.5x108CFU/mL was inoculated each flask and incubated on incubator shaker at 200 rpm. Potato

Methods (brief)

• respectively at pH4 &25OC. Cr (VI)-tolerance ability of these yeast strains used after further HPLC analysis& molecular
• Soil and effluent sample were collected from Addis Ababa urban farming site particularly from Pickok, German Goffa,
• 2355 meters above sea level. Some of the soil sample was collected from part of Rift valley at geographic coordinate
• Sample size and collection method
• 10g of soil from vegetable farm and 10mL wastewater samples from effluent waste was collected and kept in sterilized
• 150 sample were collected. Sampling point were clustered depending on vegetable types and polluted rivers, these
• were, Sald, Cabbage, Carrot, Potato, Garlic, Cauli flower, Swiss chard farm and forest . The collected samples were
• 150 soil and effluent samples were pooled into 15 composite samples depending on similar property from each site
• After 15days from enriched soil sample & effluent, 10mL was transferred into 90 mL distil water and 1 mL
• From each test tube using micropipette 0.1mL diluted sample were spread on potato dextrose agar (PDA) aseptically &
• Yeast species Code Probability Similarity Distance Specific Sample Type
• Barnettozyma, Candida, Hanseniapora, Lachancea, Lodderomyces, Metschnikowia, Pichia, Rhodotorula,
• for bioinnoculant formulation in chrome waste treatment after further HPLC analysis and molecular characterization.
• The authors are highly appreciate to acknowledge Addis Ababa urban area farmers willing to give soil sample from
• 12. Central statistical agency (2017) Agricultural sample survey 2016/2017 (2009 E.C).volume I report on area and
• waste collected from Sidama and Gedio zone. J Yeast Fungal Res 7(6):47–53

Implications

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