Allochthonous bioaugmentation in ex situ treatment of crude oil-polluted sediments in the presence of an effective degrading indigenous microbiome.

Oil-polluted sediment bioremediation depends on both physicochemical and biological parameters, but the effect of the latter cannot be evaluated without the optimization of the former. We aimed in optimizing the physicochemical parameters related to biodegradation by applying an ex-situ landfarming set-up combined with biostimulation to oil-polluted sediment, in order to determine the added effect of bioaugmentation by four allochthonous oil-degrading bacterial consortia in relation to the degradation efficiency of the indigenous community. We monitored hydrocarbon degradation, sediment ecotoxicity and hydrolytic activity, bacterial population sizes and bacterial community dynamics, characterizing the dominant taxa through time and at each treatment. We observed no significant differences in total degradation, but increased ecotoxicity between the different treatments receiving both biostimulation and bioaugmentation and the biostimulated-only control. Moreover, the added allochthonous bacteria quickly perished and were rarely detected, their addition inducing minimal shifts in community structure although it altered the distribution of the residual hydrocarbons in two treatments. Therefore, we concluded that biodegradation was mostly performed by the autochthonous populations while bioaugmentation, in contrast to biostimulation, did not enhance the remediation process. Our results indicate that when environmental conditions are optimized, the indigenous microbiome at a polluted site will likely outperform any allochthonous consortium.

Isolation, identification and analysis of antibacterial activity of soil streptomycetes isolates from north Jordan.

A total of 90 different Streptomyces isolates were recovered from 36 soil samples and assessed for their antibacterial activity. Nine isolates were identified by the absence of an aerial mycelium. The rest were grouped into six colour series, namely grey, white, yellow, green, red and polymorphic colours (pink, orange or violet) with total numbers of 29, 18, 14, 8, 3 and 9, respectively. The isolates (68%) showed a reverse side culture pigmentation, 30% produced melanin and 25% produced other soluble pigments. Isolates (48%) were characterized by flexuous spore chains, 21% with spiral and 10% for each of the rectus and retinaculum apertum arrangement. The antibiotic activity against a wide range of bacteria was exhibited by 54% of the isolates which were effective against Bacillus subtilis (57%), Staphylococcus aureus (47%), Escherichia coli (24%), Klebsiella spp (16%), and Shigella spp (12%). The lowest activity (8%) was exhibited against Pseudomonas spp and Salmonella spp. The antibacterial activity of the isolates was divided into four groups according to the diameter of the inhibition zone produced. Groups 3 and 4 with larger inhibition zones indicated their potential as a possible source of novel antibiotics.

Molecular typing of multiresistant Klebsiella pneumoniae isolated from children from northern Jordan.

Twenty-nine clinical isolates of community acquired Klebsiella pneumoniae obtained from 17 children with malnutrition were characterized by antibiotic susceptibility, plasmid analysis, and random amplified polymorphic DNA (RAPD) techniques. Disc diffusion methodology was used to test the susceptibility of the isolates to 13 antibiotics: amoxycillin, cephapirin, ceftazidime, cefoxitin, cefotaxime, aztreonam, gentamicin, ciprofloxacin, chloramphenicol, erythromycin, nalidixic acid, trimethoprim and amoxycillin-clavulanic acid. All the isolates showed multiresistance patterns (15 patterns) ranging from resistance to two antibiotics to resistance to 10 antibiotics. All isolates were resistant to amoxycillin and erythromycin. Ten K. pneumoniae isolates producing extended-spectrum beta-lactamases (ESBLs) as evidenced by the double-disc diffusion synergy test were isolated sporadically from six patients. Six of these 10 isolates were hyperproducers of ESBL, which resulted in increased resistance to the beta-lactam-beta-lactamase inhibitor combination amoxycillin-clavulanic acid. Plasmid analysis showed plasmid ranging in size from 48 kilobases (kb) to 1.4 kb. All the 29 isolates shared the same plasmid 26 kb. There was a consistent relationship between antibiotype and plasmid profiles for each pair of isolates obtained from five individual patients. RAPD analysis using a single (10-mer) primer demonstrated that the isolates that have the same antibiotype and the same plasmid profile had different RAPD fingerprint patterns. These results demonstrate that the RAPD technique is better than antibiotype characterization and a plasmid analysis profile for typing K. pneumoniae as well as for revealing strain differences.

Detection of genetic polymorphism by RAPD-PCR among isolates of Bacillus thuringiensis.

Sixteen isolates of Bacillus thuringiensis recovered from different Jordanian habitats were compared using random amplification of polymorphic DNA (RAPD) to determine whether they could be differentiated at the molecular level. Total genomic DNA from each isolate and three reference strains were amplified using 10-mer primers. Electrophoretic analysis of the amplification products revealed the incidence of polymorphism among the isolates. Pair-wise comparisons of polymorphic products were used to construct a dendrogram applying the cluster analysis. Fifteen of the isolates were all in one major cluster which was divided into six small groups. Such analysis showed some regional variation among the isolates, but did not indicate a clearly defined habitat locational pattern of the DNA polymorphism.

Use of RAPD-PCR fingerprinting to detect genetic diversity of soil Streptomyces isolates.

Random amplified polymorphic DNA (RAPD) was used for identification and assessment of genetic diversity between isolates of Streptomyces from soil. Genomic DNA from 18 Streptomyces isolates and 2 reference strains were amplified using four different 10-mer primers. Different DNA fingerprinting patterns were obtained for all the isolates. Electrophoretic and cluster analysis of the amplification products revealed incidence of polymorphism among the isolates and none of them was identical to the reference strains although there were some common amplification bands. Two highly divergent groups were determined among the isolates. The results indicate that RAPD is an efficient method for discriminating and studying genetic diversity of Streptomyces isolates.

Antibiotic susceptibility testing and plasmid profiles of Escherichia coli isolated from diarrhoeal patients.

The antibiotic resistance pattern and plasmid profiles were studied for a total of 89 Escherichia coli (E. coli) isolates recovered from faecal specimens of children hospitalized with diarrhoea in Rahma hospital for children, Irbid-Jordan. Twenty-four of these were identified as diarrhoeagenic E. coli by the polymerase chain reaction (PCR) procedure. Seventy-one E. coli isolates showed a multiple resistance pattern (to 10 antibiotics) and 13 isolates were susceptible to all antibiotics tested. All the 89 isolates were sensitive to nalidixic acid. Plasmid content and profile studies showed that the 76 E. coli drug resistant isolates (including 6 and 12 isolates that showed single resistance to tetracycline and ampicillin respectively) carried plasmids ranging from 54.0 kb to 1.5 kb in size. The number of plasmids in each of these isolates ranged from one to six of different sizes. All the E. coli isolates contained a common plasmid with a molecular weight of 25.0 kb which proved to confer resistance to ampicillin, kanamycin, tetracycline, and possibly chloramphenicol.