EMCB-ENVIS Node ENVIRONMENTAL BIOTECHNOLOGY

EMCB-ENVIS Centre
activation of the metabolism that leads to purine degradation in the filamentous freshwater
cyanobacterium Planktothrix sp. FP1. The purine catabolic pathway is related to the nitrogen
microcycle in water environments, in which cyanobacteria use traces of purines and ureides as a
nitrogen source for growth. Thus, the activity of allantoicase, a key inducible enzyme of this
metabolism, was used as tool for assaying the activation of the purine degradation pathway. The
enzyme and the pathway were induced by allantoic acid, the direct substrate of allantoicase, as
well as by adenine and, to a lower degree, by urea, one of the main products of purine
catabolism. Crude cell extract of Escherichia coli was also employed and showed the best
induction of allantoicase activity. In culture, Planktothrix sp. FP1 showed a differential
accumulation of PST in consequence of the induction with different substrates. The
cyanobacterial culture induced with allantoic acid accumulated 61.7% more toxins in comparison
with the control. On the other hand, the cultures induced with adenine, urea, and the E. coli
extract showed low PST accumulation, respectively, 1%, 38%, and 5% of the total toxins content
detected in the noninduced culture. A degradation pathway for the PSTs can be hypothesised: as
suggested for purine alkaloids in higher plants, saxitoxin (STX) and derivatives may also be
converted into xanthine, urea, and further to CO2 and NH4+ or recycled in the primary
metabolism through the purine degradation pathway.
Friedrich Widdel and Ralf Rabuszx. (Max-Planck-Institut für Marine Mikrobiologie,
Celsiusstrasse 1, D-28359 Bremen, Germany). Anaerobic biodegradation of saturated
and aromatic hydrocarbons. Current Opinion in Biotechnology, 12(3) (2001), 259-276.
Saturated and aromatic hydrocarbons are wide-spread in our environment. These compounds
exhibit low chemical reactivity and for many decades were thought to undergo biodegradation
only in the presence of free oxygen. During the past decade, however, an increasing number of
microorganisms have been detected that degrade hydrocarbons under strictly anoxic conditions.
G. M. Walker, L. R. Weatherley. (School of Chemical Engineering, The Queen's University of
Belfast, Belfast BT9 5AG, Northern Ireland, UK. Department of Chemical and Process
Engineering, University of Canterbury, Christchurch, New Zealand). Biodegradation and
biosorption of acid anthraquinone dye. Environmental Pollution, 108(2) (2000), 219-
223.
The acid anthraquinone dye Tectilon Blue (TB4R) is a major coloured component from the
aqueous effluent of a carpet printing plant in Northern Ireland. The aerobic biodegradation of
TB4R has been investigated experimentally in batch systems, using three strains of bacteria,
namely, Bacillus gordonae (NCIMB 12553), Bacillus benzeovorans (NCIMB 12555) and
Pseudomonas putida (NCIMB 9776). All three strains successfully decolourised the dye, and
results were correlated using Michaelis–Menten kinetic theory. A recalculation of the reaction
rate constants, to account for biosorption, gave an accurate simulation of the colour removal over
a 24-h period. Up to 19% of the decolorisation was found to be caused by biosorption of the dye
onto the biomass, with the majority of the decolorisation caused by utilisation of the dye by the
bacteria. The reaction rate was found to be intermediate between zero and first order at dye
concentrations of 200–1000 mg/l.
Hanumanthanaik P Doddamani, Harichandra Z Ninnekar. (Department of Biochemistry,
Karnatak University, Dharwad-580 003, India). Biodegradation of Carbaryl by a
Micrococcus Species. Current Microbiology, 43(1) (2001), 0069 – 0073.
A bacterium capable of utilizing carbaryl as sole source of carbon was isolated from garden soil
and identified as a Micrococcus species. The organism also utilized carbofuran, naphthalene, 1naphthol,
and several other aromatic compounds as growth substrates. The organism degraded
carbaryl by hydrolysis to yield 1-naphthol and methylamine. 1-Naphthol was further metabolized
via salicylate by a gentisate pathway, as evidenced by oxygen uptake and enzymatic studies.
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