On the plant growth hormone produced by Rhizopus suinus

Since it was first discovered that cell elongation in the Avena coleoptile is controlled by a hormone, our understanding of the nature and rôle of this substance has progressed considerably. Apart from the elucidation of its functions in promoting growth, tropisms, and other reactions of the plant, the chemical nature of the substance has been extensively studied. The active substance produced by cultures of the mold Rhizopus suinus was shown by Nielsen (1930) to be ether-soluble, and by Dolk and Thimann (1932) to be an unsaturated organic acid, decomposed by strong acids but not by alkalies, and readily inactivated by oxidation. Its dissociation constant, as measured by Dolk and Thimann, is 10^-4.75. Previously, Went (1928) had shown the molecular weight of the active substance in Avena coleoptiles to be about 376. The active substance in human urine was isolated by Kögl and Haagen-Smit (1931) and by Kögl, Haagen-Smit, and Erxleben (1933), and shown to be an acid, C17H28O(OH)COOH (auxin A), whose lactone is also active, while from malt these workers later isolated (1933) a ketohydroxy acid, C17H28O(OH)COOH (auxin B), which had the same activity per unit weight. On account of the rather small amount of substance available from Rhizopus cultures, and also since the bulk of the partially purified product was lost through spontaneous inactivation (see section, “Concluding stages”), the chemical investigation of the active substance, begun earlier, was dropped. However, the many experiments on purification which had meanwhile been carried out showed that the active substance from Rhizopus did not behave in quite the same way as that from urine. Recently, however, it was shown by Kögl, Erxleben, and Haagen-Smit (1934) that there is in urine a second active substance, identical with β-indolylacetic acid, and Kögl and Kostermans (1934) showed that the molecular weight of the substance produced by Aspergillus and by Rhizopus is that of β-indolylacetic acid rather than that of the C18 compounds. Since preparations from Rhixopus have been extensively used for physiological work, both in this laboratory and elsewhere, the exact nature of the active substance is of considerable interest. The present paper will give evidence that the active substance produced by Rhizopus suinus is in fact β-indolylacetic acid. Identification by the preparation of derivatives and by mixed melting points with the pure synthetic substance was not possible on account of the small amount of material available. Nevertheless, the evidence given below is fairly conclusive. The method of purification, since it differs to some extent from that adopted by Kögl and his coworkers, will also be outlined. Finally, it will be shown that some of the peculiar conditions previously found to be necessary for the production of this growth substance (Thimann and Dolk, 1933) find a simple explanation on this basis

Conventional and molecular characterization of selected Lactic acid bacteria from fermented corn gruel (ogi) and fermented milk (nono)

Fermented foods have served as important vehicle for microbial flora that have overtime formed a niche as part of the human diet. One of such is the Lactic acid bacteria which are nonpathogenic, extensively disseminated and keenly included in most fermentative procedures. This research was conducted to isolate lactic acid bacteria from fermented food sources. Pour plate method was used for the isolation of bacteria on MRS media. The bacteria isolates obtained from fermented corn gruel (ogi) and fermented milk (nono) were characterized through conventional and molecular methods. A total of six (6) bacteria isolates were recovered and identified to reveal a community of bacteria dominated by Lactobacilli sp and Bacillus sp. Specie identification was based on sequence analysis of 16SrRNA gene resulting in 4 Lactobacilli sp made up of 1 L. plantarum, 2 L acidophilus, 1 L. fabifermentan and 1 Bacillus sp. However, one of the isolates was identified as coccobacilli due to its peculiar structure on the basis of its microscopy and biochemical reaction only. The mean total aerobic bacteria plate count ranged from 2.0×102 cfu/g to 6.5x104 cfu/g. Studies continue to portray lactic acid bacteria as the predominant group of microorganisms that have undergone several studies for food fermentation and have been used extensively as potential sources of probiotics for the production of functional foods

The role of two families of bacterial enzymes in putrescine synthesis from agmatine via agmatine deiminase

Putrescine, one of the main biogenic amines associated to microbial food spoilage, can be formed by bacteriafrom arginine via ornithine decarboxylase (ODC), or from agmatine via agmatine deiminase (AgDI). This study aims to correlate putrescine production from agmatine to the pathway involving N-carbamoylputrescine formation via AdDI (the aguAproduct) and N-carbamoylputrescine amidohydrolase (the aguB product), or putrescine carbamoyltransferase (the ptcA product) in bacteria. PCR methods were developed to detect the two genes involved in putrescine production from agmatine.Putrescine production from agmatine could be linked to the  aguA and  ptcA genes in  Lactobacillus hilgardii X1B,Enterococcus faecalis ATCC 11700, and Bacillus cereus ATCC 14579. By contrast Lactobacillus sakei 23K was unable toproduce putrescine, and although a fragment of DNA corresponding to the gene aguA was amplified, no amplification wasobserved for the ptcA gene. Pseudomonasaeruginosa PAO1 produces putrescine and is reported to harbour aguA and aguBgenes, responsible for agmatine deiminase and N-carbamoylputrescine amidohydrolase activities. The enzyme from P. aeruginosa PAO1 that converts N-carbamoylputrescine to putrescine (the aguB product) is different from other microorganismsstudied (the ptcA product). Therefore, the aguB gene from P. aeruginosa PAO1 could not be amplified with ptcA specificprimers. The aguB and ptcA genes have frequently been erroneously annotated in the past, as in fact these two enzymes areneither homologous nor analogous. Furthermore, the aguA, aguB and ptcA sequences available from GenBank were subjected to phylogenetic analysis, revealing that gram-positive bacteria harboured ptcA, whereas gram-negative bacteria harbouraguB. This paper also discusses the role of the agmatine deiminase system (AgDS) in acid stress resistance.&nbsp

Effect of riboflavin-producing bacteria against chemically induced colitis in mice

Aim: To assess the anti-inflammatory effect associated with individual probiotic suspensions of riboflavin-producing lactic acid bacteria (LAB) in a colitis murine model. Methods and Results: Mice intrarectally inoculated with trinitrobenzene sulfonic acid (TNBS) were orally administered with individual suspensions of riboflavin-producing strains: Lactobacillus (Lact.) plantarum CRL2130, Lact. paracasei CRL76, Lact. bulgaricus CRL871 and Streptococcus thermophilus CRL803; and a nonriboflavin-producing strain or commercial riboflavin. The extent of colonic damage and inflammation and microbial translocation to liver were evaluated. iNOs enzyme was analysed in the intestinal tissues and cytokine concentrations in the intestinal fluids. Animals given either one of the four riboflavin-producing strains showed lower macroscopic and histologic damage scores, lower microbial translocation to liver, significant decreases of iNOs+ cells in their large intestines and decreased proinflammatory cytokines, compared with mice without treatment. The administration of pure riboflavin showed similar benefits. Lact. paracasei CRL76 accompanied its anti-inflammatory effect with increased IL-10 levels demonstrating other beneficial properties in addition to the vitamin production. Conclusion: Administration of riboflavin-producing strains prevented the intestinal damage induced by TNBS in mice. Significance and Impact of the Study: Riboflavin-producing phenotype in LAB represents a potent tool to select them for preventing/treating IBD.Fil: Levit, Romina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Centro de Referencia Para Lactobacilos; ArgentinaFil: Savoy, Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Centro de Referencia Para Lactobacilos; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia; ArgentinaFil: de Moreno, Maria Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Centro de Referencia Para Lactobacilos; ArgentinaFil: Leblanc, Jean Guy Joseph. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Centro de Referencia Para Lactobacilos; Argentin

Preliminary characterization of a Moroccan honey with a predominance of Bupleurum spinosum pollen

Honey with Bupleurum spinosum (zandaz) as a main pollen source has not been the subject of previous detailed study. Therefore, twelve Moroccan samples of this honey were subjected to melissopalynological, physicochemical and microbiological quality characterization, as well as antioxidant activity assessment. From a quality point of view, almost all samples were within the limits established by Codex Alimentarius, and/or the European legislation. All samples presented predominance of B. spinosum pollen (more than 48%). Relatively high levels of trehalose (1.3-4.0 g/100 g) and melezitose (1.5-2.8 g/100 g) were detected. Those sugars, not common in monofloral honeys, could be used as an important factor to discriminate zandaz honey. Flavonoid content correlated positively with the honey color, melanoidin and polyphenol content, and negatively with the IC50 values of scavenging ABTS (2,2' - azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) free radicals, while proline amount correlated negatively with IC50 values of nitric oxide scavenging activity and chelating power. This correlation supports the use of anti-oxidant activities as important variables for PCA (principal component analysis). Both components explained 70% from the given data, and showed certain homogeneity upon analyzed samples independent of the region, suggesting the importance of B. spinosum nectar in the resulting honey characteristics.Fundacao para a Ciencia e Tecnologia for Research Center [UID/BIM/04773/2013 CBMR 1334, UID/AGR/00239/2013, UID/BIA/04050/2013 (POCI-01-0145-FEDER-007569)]; ERDF through the COMPETE - Programa Operacional Competitividade e Internacionalizacao (POCI

A pilot microbial assessment of beef sold in the Ashaiman market, a suburb of Accra, Ghana

Food safety is a matter of great public health concern worldwide and particularly crucial if the environment in which the food is handled is heavily contaminated. Most fresh foods particularly that of animal origin like beef is highly susceptible to microbial invasion and food poisoning. In poorly managed market environment particularly in Ghana, unhygienic practice is the major cause for food contamination. This study observed the hygienic practices and microbiological food safety standards of butchers who specifically sold beef in the Ashaiman market in Accra, Ghana. Hygienic practices of sixteen (16) butchers were randomly selected in a cross sectional study using an eight point scale checklist weekly over a period of four weeks. The microbial quality of one hundred and twenty-eight (128) fresh beef samples were aseptically collected and analysed using standard microbiological techniques. It was observed that majority of the butchers did not practice safe hygiene standards as recommended by the Ghana Food and Drugs Board and the Ghana Standards Board. The beef samples were contaminated with Aerobic mesophiles (189-23000 cfu/g), Staphylococcus aureus (22-59 cfu/g), Bacillus cereus (17-41 cfu/g), Clostridium perfringens (21-48 cfu/g) and Escherichia coli (31-2200 cfu/g). The pH of the beef samples were between 6.50 and 6.90. The butchers in Ashaiman market supplied fairly contaminated beef to the general public. Escherichia coli , which is a sign of faecal contamination, was the predominant microbial contaminant in the samples examined. The result of unhygienic practices and poor handling of beef by butchers in the Ashaiman market is the major cause of contaminated beef. There are chances that other meat sold by virtually the same group of persons could equally or even more be contaminated by food borne pathogens. Hence food industry and consumers should be made aware of the potential risk of food borne pathogens in beef sold by butchers in Ashaiman market

Growth and metabolic characteristics of fastidious meat-derived Lactobacillus algidus strains

Lactobacillus algidus is a meat spoilage bacterium often dominating the bacterial communities on chilled, packaged meat. Yet, L. algidus strains are rarely recovered from meat, and only few studies have focused on this species. The main reason limiting detailed studies on L. algidus is related to its poor growth on the media routinely used for culturing food spoilage bacteria. Thus, our study sought to develop reliable culture media for L. algidus to enable its recovery from meat, and to allow subculturing and phenotypic analyses of the strains. We assessed the growth of meat-derived L. algidus strains on common culture media and their modifications, and explored the suitability of potential media for the recovery of L. algidus from meat. Moreover, we determined whether 12 meat-derived L. algidus strains selected from our culture collection produce biogenic amines that may compromise safety or quality of meat, and finally, sequenced de novo and annotated the genomes of two meat-derived L. algidus strains to uncover genes and metabolic pathways relevant for phenotypic traits observed. MRS agar supplemented with complex substances (peptone, meat and yeast extract, liver digest) supported the growth of L. algidus, and allowed the recovery of new L. algidus isolates from meat. However, most strains grew poorly on standard MRS agar and on general-purpose media. In MRS broth, most strains grew well but a subset of strains required supplementation of MRS broth with additional cysteine. Supplementation of MRS broth with catalase allowed growth in aerated cultures suggesting that the strains produced hydrogen peroxide when grown aerobically. The strains tested (n = 12) produced ornithine from arginine and putrescine from agmatine, and two strains produced tyramine from tyrosine. Our findings reveal that L. algidus populations are underestimated if routine culture protocols are applied, and prompt concerns that L. algidus may generate tyramine or putrescine in meat or fermented meat products.Peer reviewe

Developments in the fermentation process and quality improvement strategies for mead production

Mead is a traditional alcoholic drink derived from the fermentation of diluted honey in the presence of appropriate yeast. Its modern production, in general terms, involves the addition of nutrients to initial diluted honey, pasteurization, yeast inoculation, fermentation and removal of impurities. Undesirable events along the process have been reported; among them, we highlight: delayed or arrested fermentations, modified and unpleasant sensory and quality parameters of the final product. These problems have been linked to the inability of yeasts to accomplish their role in extreme growth conditions. Emphasis has also been placed on the long fermentation times required, ranging from weeks to months, particularly when traditional procedures are applied and when the honey concentration is low. A series of alterations to the must and technological changes have been proposed in order to optimize the mead production process. In this context, this review examines the evidence that aims to improve meads’ quality and make the production process easier and more efficient, by clarifying the source of unexpected events, describing the implementation of different fermentative microorganisms and using new methodologies