Pectin Agar Research Articles

SCREENING OF PECTINASE PRODUCING THERMOPHILIC MUCOR SP. ISOLATED FROM DECOMPOSTING FRUITS AND VEGETABLES

A thermophilic fungal strain producing pectinases was isolated afterprimary screening of 12 different isolates on modified Pectin agar medium usingdifferent compost and decomposed matter collected from the vegetable and fruitmarkets of different cities of U.P. Selection of the fungus was done based on theclearance zones and pectinase enzyme production carried out in solid statefermentation. The fungal isolate was initially identified as a Mucor sp.

The Cellulase and Pectinase Activities Associated with the Virulence of Indigenous Sclerotinia sclerotiorum Isolates in Jordan Valley

Twenty five isolates of Sclerotinia sclerotiorum were recovered from different infested fields of vegetable along the heavily cultivated crops in Jordan valley. Cellulase and pectinase activities of those isolates were detected using CMC and pectin agar media, respectively. Diameter of the clearing zones on those media represented the level of such enzymatic activities, characteristic of each isolate. The virulence of those isolates was studied using a squash (Cucurbita pipo) cultivar under a greenhouse condition. The significance of correlating the enzymatic activity with the virulence of the isolates was ascertained and discussed.

Cloning of two pectate lyase genes from the marine Antarctic bacterium Pseudoalteromonas haloplanktis strain ANT/505 and characterization of the enzymes.

A marine Antarctic psychrotolerant bacterium (strain ANT/505), isolated from sea ice-covered surface water from the Southern Ocean, showed pectinolytic activity on citrus pectin agar. The sequencing of the 16S rRNA of isolate ANT/505 indicates a taxonomic affiliation to Pseudoalteromonas haloplanktis. The supernatant of this strain showed three different pectinolytic activities after growth on citrus pectin. By activity screening of a genomic DNA library of isolate ANT/505 in Escherichia coli, two different pectinolytic clones could be isolated. Subcloning and sequencing revealed two open reading frames (ORF) of 1,671 and 1,968 nt, corresponding to proteins of 68 and 75 kDa, respectively. The deduced amino acid sequence of the two ORFs showed homology to pectate lyases from Erwinia chrysanthemi and Aspergillus nidulans. The pectate lyases contain signal peptides of 17 and 26 amino acids that were correctly processed after overexpression in E. coli BL21. Both enzymes were purified by anionic exchange chromatography. Maximal enzymatic activities for both pectate lyases were observed at 30 degrees C and a pH range of 9 to 10. The Km values of both lyases for pectate and citrus pectin were 1 g l(-1) and 5 g l(-1), respectively. Calcium was required for activity on pectic substrates, whereas the addition of 1 mM ethylenediaminetetraacetic acid (EDTA) resulted in complete inhibition of the enzymes. These two enzymes represent the first pectate lyases isolated and characterized from a cold-adapted marine bacterium.

Colonization of Retama raetam seeds by fungi and their significance in seed germination

Examination by scanning electron microscopy and incubation on potato-dextrose agar medium showed that dry seeds ofRetama raetam were externally free of fungi. When planted in sandy loam soil, the seeds become colonized with eleven soil-borne fungal species. The fungi were isolated on cellulose agar, pectin agar and lignin agar media.Aspergillus flavus, A. niger, A. fumigatus, Penicillium capsolatum andFusarium oxysporum had broad occurrence and were recovered on all the three media. The production of hydrolytic enzymes by the isolated fungi depends on the substrate and species.Penicillium capsolatum, P. spinulosum andA. niger had wide enzymatic amplitude and they were able to produce cellulolytic, pectolytic and lignolytic activities on corresponding substrates as well as on seed-coat-containing media. The lignolytic activities of the isolated species exceptChaetomium bostrychodes andTrichoderma viride were enhanced by applying the seed-coat materials as C- source rather than lignin. SoakingR. raetam seeds in culture filtrates of most of the fungi grown on seed-coat-supplemented media induced a pronounced and distinct stimulating effect on seed germination. The most effective filtrates were those ofP. capsolatum, P. spinulosum andSporotrichum pulverulentum.

Research Note: The Presence of Yersinia enterocolitica and Other Yersinia Species on the Carcasses of Market Broilers

Sixty ready-to-cook broiler carcasses obtained from several local supermarkets were tested for the presence of Yersinia enterocolitica and other Yersinia species. In the present study, the authors used two enrichment broths, yeast-extract/rosebengal-bile oxalate sorbose (YER-BOS) and phosphate-buffered saline with a postenrichment KOH treatment (PBS-KOH), and two plating media, cefsulodin-irgasan-novobiocin (CIN) and pectin agar. Yersinia organisms were found on 34 of 60 carcasses (56.7%) and Y. enterocolitica, on 16 of 60 carcasses (26.7%). There was no significant difference between CIN and pectin agar; however, PBS-KOH yielded a significantly higher (P≤.05) detection rate than YER-BOS, regardless of the plating media used. In addition to Y. enterocolitica, Y. frederiksenii and Y. intermedia were also isolated from the market broilers. None of the Y. enterocolitica isolates were found to be presumptively virulent.

Detection of pectolytic activity andpel homologous sequences inFrankia

Using a cup-plate pectin agar assay, pectolytic activity was detected in nodule filtrates obtained fromAlnus rugosa (DuRoi) Spreng,A. glutinosa (L.) Gaertn andA. crispa (Ait.) Pursh seedlings after infection with twoFrankia strains (ACN1AG, CpI1). Pectolytic activity was also detected in cultures filtrates of the same twoFrankia isolates afterin vitro-cultivation on Qmod pectin liquid medium. When Southern blots of Frankia total DNAs from 3 isolates ofF. alni subsp.Pommerii (ACN1AG, ArI3, and CPX32b) and 3 isolates ofF. elaeagni (EUN1 pec, SCN 10a and TX31eHR) were hybridized withPelBDA probes fromErwinia chrysanthemi, positive signals were found in all 7 Frankiae tested.

Isolation of Pectinolytic Aeromonas hydrophila and Yersinia enterocolitica from Vacuum-Packaged Pork

A survey was made of commercially available vacuum-packaged fresh pork held at 5 C for 7, 14, 21 and 28 days. Also, four vacuum-packaged leg roasts were stored for 21 days at 5 C then for 90 days at −18 C before sampling. Surface cores of meat were enriched in sorbitol bile broth 21 days at 5 C to enhance recovery of Yersinia enterocolitica on pectin agar. Of the 54 samples surveyed, 20% yielded highly pectinolytic colonies of Aeromonas hydrophila that were cytotoxic to Y1 and HeLa cells, 6% yielded Y. enterocolitica and 6% yielded Yersinia intermedia. Yersinia was recovered from both fresh and frozen samples. This is believed to be the first report of pectinolysis by A. hydrophila and recovery of cytotoxic A. hydrophila from vacuum-packaged pork.

Vergleichende Anwendung von zwei Anreicherungsverfahren and fünf Selektivnährböden zur Isolierung von Yersinia enterocolitica aus Tonsillen von Schlachtschweinen

115 tonsils of healthy slaughter pigs were culturally examined for presence of Yersinia (Y.) enterocolitica. For this purpose each sample was enriched both in phosphate buffered saline solution (pH 7.6; stored at 4 °C and plated every week, thrice all together) and modified Rappaport broth (plated after an incubation of two days at 22 °C). Each such enrichment was plated on 5 different selective media: Yersinia selective agar proposed by Wauters (1973), deoxycholate-citrate-mannitol agar ( Saari and Jansen, 1979), pectin agar ( Bowen and Kominos), Mac Conkey and Leifson agar as used in the routine diagnostic of Enterobacteriaceae. Each agar plate was incubated at 28 °C for two days. By cold enrichment method were isolated 11 strains of human pathogenic Y. enterocolitica (9 X 0-group I syn. serotype O : 3 ; 2 X 0-group V syn. serotype O:9). With the modified Rappaport medium were recovered 33 strains (24 X O-group I, 9 X O-group V). The most recoveries were done over the Yersinia selective agar with 65.2%, then followed deoxycholate-citrate-mannitol agar with 57.6%, Leisfon agar with 45.5%, Mac Conkey agar with 42.3% and pectin agar only with 18.2% of the isolations. Not only the type of enrichment medium has a marked effect in the recovery efficiency of Y. enterocolitica out of samples but also number and type of the used selective media on which the enrichment is plated.

Evaluation of a Pectin Agar Medium for Isolation of Yersinia Enterocolitica within 48 Hours

A modified pectin agar medium was evaluated for the rapid isolation and presumptive identification of Yersinia enterocolitica. Of 118 isolates of Enterobacteriaceae tested, only the 13Y. enterocolitica and the three Klebsiella oxytoca strains produced colonies that depressed and sank into the agar. Yersinia enterocolitica was also easily identified in mixed cultures, even from inocula containing three times as many other Enterobacteriaceae organisms as Y. enterocolitica. The recovery of Y. enterocolitica was evaluated on Mueller-Hinton, pectin, Hektoen enteric, xylose lysine desoxycholate, Salmonella-Shigella, and MacConkey agars. Compared with Mueller-Hinton agar, the pectin agar showed a 100% recovery of Y. enterocolitica, with all strains having depressed colonies, while the other media showed lesser recoveries of only 5 to 25%, with no other discriminating colonial characteristic.

Pectolytic enzymes in Rhizobium.

A sensitive pectin agar plate assay was used to demonstrate low levels of pectolytic enzymes in infective and noninfective strains of Rhizobium. The possible relation of this characteristic to legume infection is discussed.