Glucose-ammonium Sulphate Research Articles

Pentachlorophenol removal by Rhizopus oryzaeCDBB‐H‐1877 using sorption and degradation mechanisms

AbstractBACKGROUNDPentachlorophenol (PCP) is a pollutant of soil and water and it is very toxic to humans and aquatic life. The use of PCP is now restricted or prohibited in development countries, but many areas of the world remain contaminated. Fungi, mainly basidiomycetes, have been studied as a means to remove PCP. However, little is known of the mechanisms used by zygomycetes to remove PCP.RESULTSThe effect of two initial amounts of PCP and of two carbon and nitrogen sources on the metabolic response was assayed by determining kinetic and stoichiometric parameters of fungal growth, intermediates, sorption capacity, and abiotic losses of PCP. Independently from carbon sources, sorption was observed. Cultures with glucose–ammonium sulfate and 2 mg PCP yielded 0.116 µg of pentachloroanisole and 10.46 µg of chlorinated compounds. Cultures with glutamic acid–sodium nitrate and 2 mg PCP yielded 6.81 µg of pentachloroanisole and 2.89 µg of chlorinated compounds. Other unidentified metabolites were produced, some of them probably at high concentration.CONCLUSIONSorption is the principal mechanism used by Rhizopus oryzae CDBB‐H‐1877 to remove PCP from culture broth. However, a small fraction of sorbed PCP is degraded by means of methylation and dechlorination reactions. This biodegradation is mainly intracellular and depends on the carbon source. © 2014 Society of Chemical Industry

Production of polyesters consisting of medium chain length 3-hydroxyalkanoic acids by Pseudomonas mendocina 0806 from various carbon sources.

Pseudomonas mendocina strain 0806 was isolated from oil-contaminated soil and found to produce polyesters consisting of medium chain length 3-hydroxyalkanoates (mclPHAs). The monomers of mclPHAs contained even numbers of carbon atoms, such as 3-hydroxyhexanoate (HHx or C6), 3-hydroxyoctanoate (HO or C8), and/or 3-hydroxydecanoate (HD or C10) as major components when grown on many carbon sources unrelated to their monomeric structures, such as glucose, citric acid, and carbon sources related to their monomeric structures, such as myristic acid, octanoate, or oleic acid. On the other hand, PHA containing both even and odd numbers of hydroxyalkanoates (HA) monomers was synthesized when the strain was grown on tridecanoic acid. The molar ratio of carbon to nitrogen (C/N) had a significant effect on PHA composition: the strain produced PHAs containing 97-99% of HD monomer when grown in a glucose ammonium sulfate medium of C/N<20, and 20% HO, and 80% of the HD monomer when growth was conducted in media containing C/N>40. It was demonstrated that the HO/HD ratio in the polymers remained constant in media with a constant C/N ratio, regardless of the glucose concentration. Up to 3.6 g/L cell dry weight containing 45% of PHAs was produced when the strain was grown for 48 h in a medium containing 20 g/L glucose with a C/N ratio of 40.

Inhibitory effects of ethidium bromide on the growth kinetics of Klebsiella aerogenes, adaptation to ethidium and cross-resistance to proflavine.

The aerobic growth ofKlebsiella aerogenes adapted to a chemically defined glucose ammonium sulphate medium was studied in this medium containing ethidium bromide (EB). The viability of sensitive bacteria on solid medium decreased markedly with EB above 150 mg/liter, and only a fraction of the viable inhabitants of a colony grown with EB at 500 mg/liter survived after a second transfer on to this concentration. In liquid medium containing EB above 30 mg/liter, the logarithmic phase was composite, consisting of a slower first mode followed by a faster second mode, and with EB above 50 mg/ liter composite growth was preceded by a lag. This lag was preceded by a mass doubling and one cell division with EB below 100 mg/liter; at higher concentrations only a mass doubling occurred, and the bacteria became elongated.