Annals of Microbiology

A novel cold-adapted amylase-producing bacterium was isolated from seawater collected from Gaogong island of Jiangsu Province, China. The isolate was identified based on its phenotypes, biochemical test, and 16 S rRNA gene sequence as Pseudoalteromonas arctica and named GS230. The optimal activity temperature of isolate GS230 amylase was 30°C, and the activity decreased dramatically at temperatures above 40°C. Compared with the amylase from mesophiles and thermophiles, the cold-adapted amylase showed higher enzyme activity at low temperature and a greater degree of heat sensitivity at temperatures higher than 40°C. Ca2+ showed a significant effect on maintaining the activity of the enzyme. The α-amylase could have important applications in the food industry. A number of factors affecting the production of the extracellular amylase were investigated. Soluble starch and beef extract were the most promising carbon and nitrogen sources, respectively. When the strain was cultured at 20°C, pH 8.0 for 24 h, the amylase activity peaked at 780.4 U/ml.

Burkholderia phytofirmans PsJN is a well-known plant growth-promoting bacterium that establishes rhizospheric and endophytic colonization in different plants. PsJN inoculation promotes growth of different horticultural crops. L-Tryptophan (L-TRP) application may further improve its effectiveness, due to substrate (L-TRP)-dependent inoculum (PsJN)-derived auxins in the rhizosphere. In the present study, the substrate (L-TRP)-dependent response of PsJN inoculation to maize growth and auxin biosynthesis was evaluated under pot conditions. In vitro auxin biosynthesis by PsJN was determined in the absence and presence of L-TRP, a physiological precursor of auxins. Surface-disinfected seeds were treated with peat-based inoculum and L-TRP solutions (10−4 and 10−5 M). Results revealed that L-TRP application and PsJN inoculation, when applied separately, significantly increased the growth parameters of maize compared to untreated control. However, PsJN inoculation supplemented with L-TRP (10−5 M) gave the most promising results and significantly increased plant height, photosynthesis, chlorophyll content, root biomass and shoot biomass up to 18, 16, 45, 62 and 55 %, respectively, compared to the uninoculated control. Similarly, higher values of N, P and IAA content were observed with precursor (L-TRP)–inoculum (PsJN) interaction. The inoculant strain efficiently colonized maize seedlings and was recovered from the rhizosphere, root and shoot of plants. The results imply that substrate (L-TRP)-derived IAA biosynthesis in the rhizosphere by PsJN inoculation could be a useful approach for improving the growth, photosynthesis and nutrient content of maize plants.

A new succinic acid and lactic acid production bioprocess by Corynebacterium crenatum was investigated in mineral medium under anaerobic conditions. Corynebacterium crenatum cells with sustained acid production ability and high acid volumetric productivity harvested from the glutamic acid fermentation broth were used to produce succinic acid and lactic acid. Compared with the first cycle, succinic acid production in the third cycle increased 120% and reached 43.4 g/L in 10 h during cell-recycling repeated fermentations. The volumetric productivities of succinic acid and lactic acid could maintain above 4.2 g/(L·h) and 3.1 g/(L·h), respectively, for at least 100 h. Moreover, wheat bran hydrolysates could be used for succinic acid and lactic acid production by the recycled C. crenatum cells. The final succinic acid concentration reached 43.6 g/L with a volumetric productivity of 4.36 g/(L·h); at the same time, 32 g/L lactic acid was produced.

In the last decade, the number and diversity of nosocomial Candida infections has increased significantly, resulting in an emergent need for rapid and accurate methods for Candida identification. Therefore, the aim of this study was to evaluate the performance of three biochemical systems (Auxacolor, ID32C, and Vitek 2 YST) for the identification of Candida species, comparing them with molecular identification (polymerase chain reaction and gel agarose electrophoresis). These methods were used to assess Candida spp. (229 clinical isolates) prevalence and distribution among clinical specimens. The biochemical methods with higher percentages of correct identification were Vitek 2 YST (79.6%) and Auxacolor (78.6%). However, overall the biochemical methods assayed differed from the molecular identification. Thus, due to their rapid and precise identification, molecular methods are promising techniques for Candida species identification in clinical laboratories. Candida albicans and Non Candida albicans Candida species had a similar prevalence (50.4 and 49.6%, respectively), corroborating the epidemiological shift observed for these pathogens in the recent years.

Indigenous rhizobia were isolated from root nodules of lentil plants collected from various agro-climatic regions of India. These isolates together with four standard lentil Rhizobium strains were screened for sensitivity against eight phages. Four strains, USDA 2431, BHULR 104, BHULR 113 and BHULR 115 having restricted sensitivity to lytic phages LRP-1, LRP-4, LRP-13 and LRP-15 respectively, were characterized for both physiological and molecular characters. All strains had a generation time of between 3.8 and 5.6 h in yeast extract–mannitol (YM) broth, and colonies on YM agar plates showed an acidic reaction. Compared to other strains, strain USDA 2431 grew poorly when sucrose was the sole carbon source and showed maximum growth in arabinose-containing medium. The intrinsic antibiotic resistance level in all strains was tested against seven antibiotics and found to be high with ampicillin and kanamycin (50–60 μg ml-1) but very low with neomycin (0.03 μg ml-1). With the exception of strain BHULR 113, all strains expressed ex planta nitrogenase activity, with strain USDA 2431 showing the maximum activity (26.8 nmol C2H4 h-1 mg-1 protein) after 6 h of incubation. Genomic and phylogenetic relationships among the strains were examined by randomly amplified polymorphic DNA and 16S rRNA sequence analysis. Genetic distance varied from 0.09 to 0.23 among the strains, and the primer OPL-11 was found to be suitable for the discrimination of these strains. The 16S rRNA sequence analysis revealed 99–100% similarity with Rhizobium leguminosarum bv. viciae. These results clearly indicate that phage sensitivity is a useful marker for discriminating locally soil-adapted rhizobial strains forming effective nodules in lentil.

The genomes of Staphylococcus phages S25-3 and S25-4 (family Myoviridae, genus Twort-like viruses) were sequenced and analyzed from an evolutionary perspective. The genome-based phylogeny and genome analyses of phages S25-3 and S25-4 showed that they had diverged evolutionarily from the majority of this viral genus based on the presence of mobile genetic elements, i.e., a putative transposase and the homing endonuclease I-MsaI. These results suggest that genetic elements such as transposases and homing endonucleases are likely to be involved with the evolution of some Twort-like phages, including phages S25-3 and S25-4.

Fermentation is one of the oldest ways of processing food. Some fermented food is produced industrially, but can also be produced in an artisanal way by certain ethnic groups, called traditional fermented foods. In Mexico, there are a variety of traditional fermented beverages which are produced in an artisanal way. They include those made with maize (atole agrio, pozol, and tesgüino), fruit (tepache and colonche), and obtained by plant fermentation (pulque, tuba, and taberna). These beverages have been used since ancient times for religious and medicinal purposes. The medicinal effect may be due to fermented microorganisms. The presence of beneficial microorganisms known as probiotics provides beneficial effects to consumer health, improving the balance of intestinal host, and reducing the risk of gastrointestinal diseases, mainly. Most probiotics belong to the genus Lactobacillus, but Bifidobacterium, Bacillus, and yeast are also found. Therefore, it is important that the microbiological diversity of the beverages is studied and documented. This review includes information on the microbial diversity and probiotic potential of the most important traditional fermented beverages from Mexico.