Microbiology

The aim of this study was to determine the degree of contamination caused by Cryptosporidium oocyts
in regularly consumed salad vegetables sold at various wholesale and retail markets in northern part of Bangladesh.
A  total  number of  165  samples  of  salad  vegetables  collected  from  different  wholesale  and  retail  markets  were examined  for  detection of  Cryptosporidium  oocysts  using  sucrose  flotation medium  of  1.18  specific  gravity  and Ziehl Neelsen staining technique with some modifications. Cryptosporidium oocysts were detected in 47 (30%) of the total examined samples. About 40 Tomato, 35 Cucumber, 20 Lettuce, 35 Carrot and 35 Mint’s leaf samples were examined  while  Lettuce had the highest  (40%)  contamination rate  followed by  Tomato  (32.5%), Carrot (31.4%), Cucumber (25.7%),  and  Mint’s  leaf  (22.8%).  There  was  no  significant  difference  (x2  =  2.278;  p  <0.05)  among occurrences of Cryptosporidium oocysts in usually consumed salad vegetables sold at market. This study has shown that  salad  vegetables  sold  at  wholesale  and retail  markets  in northern part  of  Bangladesh  are  contaminated  with Cryptosporidium  oocysts,  may  pose  a  health risk  to  consumers  of  such products.  This  reveals  food  safety  and significance of public health.

Composting is one of the most successful biological processes for treatment of wastes residues. Microorganism’s activity during composting of waste materials were influenced by initial carbon/nitrogen ratios and physicochemical changes, e.g., electrical conductivity, temperature, pH, organic matter (OM) degradation, and total nitrogen (TN) losses. Compost heap was formed from mixture of rice straw, sugar beet straw and chicken manure. Also, total count of bacteria, fungi, actinomycetes, detection of pathogenic bacteria such as total and faecal coliform bacteria and salmonella were determined. Some physical and chemical analysis of compost during process was determined to determine compost maturity such as phytotoxicity and nitrification index. Thermophilic phase during composting process was decreased numbers of pathogenic microorganisms and after one month disappeared. Also, at the end of process E.C values were decreased after 4 months and germination index recorded 88.1% for maturity of compost.

Ford describes his historic discovery of then original specimens sent to London by Antony van Leeuwenhoek, 1674-1686.  These are the earliest known specimens from the dawn of microscopy, and are examined both by conventional light and scanning electron microscopy.

Nine Burkholderia cepacia complex (Bcc) bacteria were isolated during environmental surveys for the ecological niche of Burkholderia pseudomallei, the aetiological agent of melioidosis, in the Northern Territory of Australia. They represented two multi-locus sequence analysis-based clusters, referred to as Bcc B and Bcc L. Three additional environmental and clinical Bcc B isolates were identified upon deposition of the sequences in the PubMLST database. Analysis of the concatenated nucleotide sequence divergence levels within both groups (1.4 and 1.9 %, respectively) and towards established Bcc species (4.0 and 3.9 %, respectively) demonstrated that the two taxa represented novel Bcc species. All 12 isolates were further characterized using 16S rRNA and recA gene sequence analysis, RAPD analysis, DNA base content determination, fatty acid methyl ester analysis and biochemical profiling. Analysis of recA gene sequences revealed a remarkable diversity within each of these taxa, but, together, the results supported the affiliation of the two taxa to the Bcc. Bcc B strains can be differentiated from most other Bcc members by the assimilation of maltose. Bcc L strains can be differentiated from other Bcc members by the absence of assimilation of N-acetylglucosamine. The names Burkholderia stagnalis sp. nov. with type strain LMG 28156T ( = CCUG 65686T) and Burkholderia territorii sp. nov. with type strain LMG 28158T ( = CCUG 65687T) are proposed for Bcc B and Bcc L bacteria, respectively.

Four PGPR isolates of bacteria, designated as AK1, AK2, AK3
and AK4 were successfully isolated and characterized.
To investigate the effects of PGPR isolates on the growth of cauliflower, a pot culture experiment was conducted.
Isolates AK1, AK2, AK3
and AK4 showed the production of indole acetic acid (IAA), whereas the isolates AK2
, AK3
and AK4 isolate were able to solubilize phosphorus. All the isolates resulted in a significant increase in plant
height, root length and dry matter production of shoot and root of cauliflower plant compared to the control.
PGPR were characterized based on its cultural, morphological and biochemical characters. Pot experiments
showed that the PGPR treated seeds grew better than the untreated seeds. The present work suggests that the use
of PGPR isolates AK1
, AK2
, AK3
and AK4
as inoculants biofertilizers might be beneficial for cauliflower cultivation
as they enhanced growth of cauliflower by inducing IAA production and phosphorus solubilization.

Enhanced biological phosphorus removal
(EBPR) from wastewater relies on the preferential selection
of active polyphosphate-accumulating organisms (PAO) in
the underlying bacterial community continuum. Efficient
management of the bacterial resource requires understanding
of population dynamics as well as availability of bioanalytical
methods for rapid and regular assessment of relative
abundances of active PAOs and their glycogen-accumulating
competitors (GAO). A systems approach was adopted here
toward the investigation of multilevel correlations from the
EBPR bioprocess to the bacterial community, metabolic, and
enzymatic levels. Two anaerobic-aerobic sequencing-batch
reactors were operated to enrich activated sludge in PAOs and
GAOs affiliating with “Candidati Accumulibacter and Competibacter
phosphates”, respectively. Bacterial selection was
optimized by dynamic control of the organic loading rate and
the anaerobic contact time. The distinct core bacteriomes
mainly comprised populations related to the classes
Betaproteobacteria, Cytophagia, and Chloroflexi in the PAO
enrichment and of Gammaproteobacteria, Alphaproteobacteria,
Acidobacteria, and Sphingobacteria in the GAO enrichment. An
anaerobic metabolic batch test based on electrical conductivity
evolution and a polyphosphatase enzymatic assay were developed for rapid and low-cost assessment of the active
PAO fraction and dephosphatation potential of activated
sludge. Linear correlations were obtained between the PAO
fraction, biomass specific rate of conductivity increase under
anaerobic conditions, and polyphosphate-hydrolyzing activity
of PAO/GAO mixtures. The correlations between PAO/
GAO ratios, metabolic activities, and conductivity profiles
were confirmed by simulations with a mathematical model
developed in the aqueous geochemistry software PHREEQC.