Assembly of the bacterial flagellar filament requires a type III export pathway for ordered delivery of structural subunits from the cytosol to the cell surface. This is facilitated by transient interaction with chaperones that protect subunits and pilot them to dock at the membrane export ATPase complex. We reveal that the essential export protein FliJ has a novel chaperone escort function in the pathway, specifically recruiting unladen chaperones for the minor filament-class subunits of the filament cap and hook-filament junction substructures. FliJ did not recognize unchaperoned subunits or chaperone-subunit complexes, and it associated with the membrane ATPase complex, suggesting a function postdocking. Empty chaperones that were recruited by FliJ in vitro were efficiently captured from FliJ-chaperone complexes by cognate subunits. FliJ and subunit bound to the same region on the target chaperone, but the cognate subunit had a Ϸ700-fold greater affinity for chaperone than did FliJ. The data show that FliJ recruits chaperones and transfers them to subunits, and indicate that this is driven by competition for a common binding site. This escort mechanism provides a means by which free export chaperones can be cycled after subunit release, establishing a new facet of the secretion process. As FliJ does not escort the chaperone for the major filament subunit, cycling may offer a mechanism for export selectivity and thus promote assembly of the junction and cap substructures required for initiation of flagellin polymerization.protein secretion ͉ secretion pilots ͉ type III export

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Listeria monocytogenes, the causative agent of human listeriosis is widely distributed in nature and a major threat to human health. Aiming to investigate the environmental distribution of this pathogen in Bangladesh, the current study conducted an initial investigation on 30 soil samples and 20 surface water samples for the presence of the pathogenic Listeria monocytogenes. Based on cultural, morphological, biochemical tests and presence of the virulent gene hly, 7 (14%) Listeria monocytogenes were obtained of which, surface water samples contained four Listeria monocytogenes (15%) while, three Listeria spp. (13.33%) were isolated from soil samples. Antibiotic resistance profile of the Listeria isolates showed that 100% isolates were resistant to erythromycin and resistance to oxacillin, ampicillin, sulphamethoxazole-trimethoprim and penicillin was 71%, 57%, 43% and 43% respectively. 71% Listeira monocytogenes isolates were sensitive to vancomycin and 100% sensitivity was observed to imipenem. This study shows that multi-drug resistant pathogenic Listeria monocytogenes is widely spread in soil and water samples in Dhaka and imposes great risk to public health. Bangladesh J Microbiol, Volume 33, Number 1-2, June-Dec 2016, pp 39-42

Pollution of the environment with toxic heavy metals is spreading throughout the world along with industrial progress. Removal of these toxic heavy metals by using bacteria has achieved growing attention in recent years. The present study focuses on isolation of lead and chromium tolerant Bacillus spp., from the Buriganga and the Shitalkhya, the two major rivers surrounding Dhaka. A total of 25 Bacillus spp. isolates tolerant to 50 ppm lead and chromium were preliminarily identified based on morphological and biochemical analysis. Further investigation revealed that all isolates were also able to grow at 1000 ppm lead and 400 ppm chromium, while tolerance to 1500 ppm lead and 500 ppm chromium was observed among 48% and 76% isolates, respectively. All isolates were also able to grow at 50 ppm copper and 50 ppm zinc, while 72% grew at 100 ppm copper. The heavy metal tolerant Bacillus spp were also multi drug resistant and showed resistance to Tetracycline (100%), Ceftazidime (100%), Ceftriaxone (100%), Ampicillin (28%) and Nalidixic acid (24%).

Pollution of the environment and food with toxic heavy metals is being intensified in Bangladesh with industrial development. Consumption of foods and water contaminated with heavy metals imposes threat to human health. Aiming to find a solution to this problem, the present study focuses on probiotic Lactobacillus spp. with potential to remove heavy metals from environment as well as human body. A total of three Lactobacillus spp were isolated from curd samples and were identified based on their morphological and biochemical properties. These isolates were tolerant to low pH and bile salt which aids in their application in human gut. All isolates could tolerate 600 ppm chromium, 400 ppm lead, 400 ppm copper and 400 ppm zinc. The heavy metal tolerant Lactobacillus spp were also multi drug resistant and showed 100% resistance to Azithromycin, Cloxacillin, Gentamicin, Vancomycin, Streptomycin, Nalidixic acid, Trimethoprim-Sulfamethoxazole and Penicillin, while 100% sensitivity was observed to Imipenem. Bangladesh J Microbiol, Volume 34 Number 1 June 2017, pp 43-46