Phenols present in the wastewater discharged from many phenol based industries act as antimicrobial agents and hence biological treatment of phenol laden wastewater to a standard level prescribed by the Environmental Protection Agency is difficult. In the present investigation, a biocatalyst was developed by immobilizing cells of a mutant strain of Pseudomonas pictorum (MU 174) onto rice bran-based activated carbon. Phenol in wastewater was observed to be degraded up to 3g/l under batch studies. A removal of 99.9% of phenol in domestic wastewater was achieved at a hydraulic retention time (HRT) of 24h with a biocatalyst packed reactor under continuous flow studies. The biocatalyst had a reasonable shelf life after its preparation and had the desirable recycle capacity.
Two β-glucosidase (βG) components, βG1 and βG2, purified from extracellular culture filtrate of Trichoderma pseudokoningii S38 by chromatography techniques, showed transglycosylation activity, the character of which was previously believed to belong to the membrane-bound βG. βG1 also hydrolyzed cellobiose (and other β-linked disaccharides) to produce glucose, and could hydrolyze p-nitrophenyl-β-D-glucoside (PNPG). However, the activity of hydrolysis of disaccharides and PNPG of βG2 was lower than that of βG1, but it had higher transglycosylation activity, showing different substrate specificities. The transcosylation products originating from cellobiose by βGs, such as all of the other β-linked disaccharides and even cellotriose, were determined by HPLC. Among them, gentiobiose was believed to be the most effective inducer of cellulose biosynthesis in this strains. The induction ability of a certain disaccharide had a relationship with its amount in the traction mixture which was controlled by the dual activities of βG, hydrolysis and transglycosylation.
Geotrichum sp. FO 274A was isolated as a microorganism capable of assimilating sardine oil as the sole carbon source. Three FO 274A lipases were purified by ion exchange and hydrophobic interaction chromatographies and termed Lipases A, B and C. Lipases A and C hydrolyzed most of the ester bond of the fatty acids contained in sardine oil. Lipase B preferentially hydrolyzed the ester bond of the fatty acids of C16 or C18 having the cis double bond at the 9-position. The hydrolysis rate for sardine oil under indicated conditions increased when combinations of the purified lipases were used instead of each purified lipase. A combination of Lipases A and C showed the highest hydrolysis rate for sardine oil. The lipases from Geotrichum sp. FO 274A showed the highest hydrolysis rate for sardine oil compared with the lipases similarly isolated from other Geotrichum sp.
We cloned, sequenced and characterized the psbA2 gene of the cyanobacterium Microcystis aeruginosa K-81 strain. The deduced amino acid sequence of PsbA2 exhibited extensive similarity to the D1 protein, which is known to be a core protein in the reaction center of the photosynthetic Photosystem II in cyanobacteria. The N-terminal amino acid sequence of PsbA2 also showed that this protein is a Form II type of D1 protein, as defined for Synechococcus sp. strain PCC 7942. The psbA2 gene was transcribed as a 1.2kb monocistron, and the potential promoter had an Escherichia coli consensus sequence. The light-responsive psbA2 message exhibited rhythmicity under conditions of constant darkness after prior entrainment to light and dark cycles.
The effects of the sodium salts of acetic, propionic, butyric (volatile fatty acids, VFAs) and lactic acids on the growth of Streptococcus bovis JB1 were studied. Increasing concentrations (0.05-0.3M) of VFAs or lactic acid produced progressive drops in the S. bovis growth rate. With concentrations of 0.1M and higher, the inhibition was greater at pH 5.5 than at pH 6.5. Minimum relative growth rates of 0.65 and 0.56 were produced by 0.3M of butyric (at pH 6.5) and lactic (at pH 5.5) acids, respectively. The inhibitory potency at pH 6.5 decreased in the order butyrate>propionate>acetate=lactate, while at pH 5.5 the order was lactate=butyrate>propionate>acetate. The inhibition elicited by acetate and lactate at pH 6.5 was similar to the inhibition caused by NaCl, but at pH 5.5, all the acids were more inhibitory than NaCl. Ethyleneglycol did not affect growth in any case. The effects of VFAs in mixtures seemed to differ from their effects when tested separately. It is suggested that the inhibitions observed resulted from both the increased ionic strength in the medium and the ability of the acids to solubilize in the bacterial membrane and affect intracellular enzymes.
We designed a simple method that assesses the ability of aerobic microorganisms in soils to degrade 4-chlorobiphenyl (4-CB) to 4-chlorobenzoic acid. We screened bacteria in 46 soil samples collected from fields, paddy fields and gardens for strains that grew on biphenyl and degraded 4-CB. Sixty-five strains that utilized biphenyl were isolated from 21(46%) of 46 soil samples, a high frequency. A simple screening method that used high-pressure liquid chromatography showed that 62 (95%) of the 65 strains that used biphenyl also degraded 4-CB. The results of metabolite analysis indicated that each isolate, without exception, produced 4-chlorobenzoic acid in a, culture medium with a transitory yellow tinge. Metabolites of 4-CB were further investigated in an assay that used resting cells of Bacillus sp. strain TH 1171. The yellow metabolite was found to be 2-hydroxy-6-oxo-6-(4′-chlorophenyl)hexa-2, 4-dienoic acid from the mass spectrum of its trimethylsilyl derivative. We examined the ability of the resting cells of strain TH 1171 incubated for 24h with a mixture of PCB congeners to degrade PCB by gas chromatography-mass spectrometry. Congeners 2-, 3-, and 4-chlorobiphenyl completely disappeared during incubation. 2, 2′-, 2, 3′-, and 2, 4′-Dichlorobiphenyl and 2, 4-, 2, 5-, and 2, 6-dichlorobiphenyl were transformed into mono- and dichlorobenzoic acids, respectively. The resulting degradation of 2, 2′-, 2, 3′-, and 2, 4′-dichlorobiphenyl indicates that strain TH 1171 degrades chlorophenyl moieties of the PCB congeners. A possible biodegradation pathway of 4-CB via 2, 3-dihydroxy-4′-chlorobiphenyl is proposed.
Homospermidine synthase (HSS) catalyses the formation of the polyamine homospermidine from 2mol of putrescine. The general and kinetic properties of purified HSS from Rhodopseudomonas viridis are given and compared with those of the respective enzymes from other sources. The R. viridis enzyme is shown to catalyse a number of side reactions: (I) In the presence of putrescine or spermidine as donors of the 4-aminobutyl moiety, various homologous diamines are transformed into the respective N-(4-aminobutyl)derivatives. (II) In the absence of putrescine, spermidine as a substrate yields homospermidine, putrescine and diaminopropane as reaction products. The mechanism of the reactions catalysed by HSS and its role in the formation of uncommon bacterial polyamines are discussed. Overexpression of the homospermidine synthase (hss) gene in Escherichia coli revealed the formation of two HSS-products, homospermidine and N-(4-aminobutyl)-cadaverine, which are absent from wild-type E. coli. Expression of the hss gene in E. coli does not dramatically affect the pool concentrations of the cellular polyamines.
Small subunit ribosomal RNA gene sequences were determined in six species of the genus Tilletiopsis, in addition to Tilletiaria anomala. The phylogenetic trees were constructed for the species of the genus Tilletiopsis, in addition to T. anomala and related taxa by neighbor-joining and maximum likelihood methods. The phylogenetic trees showed that the basidiomycetous yeasts and related taxa were divided into three main clusters. Six species of the genus Tilletiopsis, in addition to T. anomala, constituted a cluster with Sympodiomycopsis paphiopedili, Tilletia caries, Ustilago hordei and U. maydis (cluster 1). In cluster 1, Tilletiopsis species and T. anomala constituted a subcluster with S. paphiopedili and T. caries (cluster 1b). The reliability of cluster lb was statistically well supported. On the other hand, Sporobolomyces roseus, the type species of the genus Sporobolomyces, was located at cluster 2 together with Bensingtonia species, Erythrobasidium hasegawianum, Kondoa malvinella, Leucosporidiumscottii, Rhodosporidium toruloides and Sporidiobolus johnsonii. This result clearly showed the phylogenetic divergence between the genera Tilletiopsis and Sporobolomyces; whereas the genera Tilletiopsis and Sporobolomyces have common chemotaxonomic characteristics, i.e., the lack of xylose in the cells and the possession of Q-10 as the major ubiquinone.