Pathotyping and antimicrobial susceptibility testing of Escherichia coli isolates from neonatal calves

Neonatal calf mortality is a major concern to livestock sector worldwide. Neonatal calf diarrhoea (NCD), an acute severe condition causes morbidity and mortality in calves. Amongst various pathogens involved in NCD, E. coli is considered as one of the major causes. The study was targeted to characterize E. coli isolates from neonatal calves for diarrhoeagenic Escherichia coli (DEC) types (pathotyping), antimicrobial resistance (AMR) profiling and to correlate with epidemiological parameters. From neonates, a total of 113 faecal samples were collected, out of that 308, lactose fermenting colonies were confirmed as E. coli. Pathotypable isolates (12.3%) were represented by STEC (6.1%), EPEC (2.9%), ETEC (1.9%), EAEC (0.9%) and EHEC (0.3%). Occurrence of STEC was more in non-diarrhoeic calves, whereas ETEC was observed more in diarrhoeic calves. EPEC occurrence was observed in both diarrhoeic and non-diarrhoeic calves. Fishers extract test showed no significant association for occurrence of DEC types to type of dairies, health status, species, breed, age and sex of neonatal calves. Two hundred and eighty isolates were tested for antimicrobial susceptibility. The isolates showed maximum resistance towards ampicillin (55.4%) followed by tetracycline (54.3%), while minimum resistance was observed towards meropenem (2.5%). Multidrug resistant E. coli isolates were found to be 139 (49.6%), and Extended-spectrum beta-lactamase (ESBL) producers were 120 (42.9%). DEC pathotypes like STEC, ETEC, EHEC and EAEC that are also multidrug resistant present in neonatal calves have zoonotic potential and hence are of public health significance.

     

Litter production and decomposition dynamics in moist deciduous forests of the Western Ghats in Peninsular India

A field study was conducted in the moist deciduous forests of the Western Ghats (India) to test the following three hypotheses: (1) Litter production in tropical forests is a function of the floristic composition, density, basal area and disturbance intensity; (2) Decay rate constants of tropical species is an inverse function of the initial lignin/nitrogen ratio; (3) Decomposition rates in tropical forests are faster than temperate forests.

Litter fall was estimated by installing 63 litter traps in the moist deciduous forests of Thrissur Forest Division in the Western Ghats at three sites. Litter fall followed a monomodal distribution pattern with a distinct peak during the dry period from November–December to March–April.Dillenia pentagyna, Grewia tiliaefolia, Macrosolen spp.,Xylia xylocarpa, Terminalia spp.,Lagerstroemia lanceolata, Cleistanthus collinus, Bridelia retusa, andHelicteres isora were the principal litter producing species at these sites. The annual litter fall ranged from 12.18 to 14.43 t ha⁻¹. Structural attributes of vegetation such as floristic composition, basal area, density and disturbance intensity did not directly influence litter fall rates.

Leaf litter decay rates for six dominant tree species were assessed following the standard litter bag technique. One hundred and eight litter bags per species containing 20 g samples were installed in the forest floor litter layer at the same three sites selected for the litter fall quantification exercise. The residual litter mass decreased linearly with time for all species. In general, less disturbed sites and species adapted to higher nitrogen availabilities exhibited relatively higher decay rate coefficients (k). The rapid organic matter turnover observed in comparison with published temperate forest litter decay rates confirms that tropical moist deciduous forest species are characterised by faster decomposition rates.

Mean concentrations of N, P and K in the litter were profoundly variable amongst the dominant species. Initial nitrogen content of the leaf litter varied from 0.65 to 1.6%, phosphorus from 0.034 to 0.077% and potassium from 0.25 to 0.62%.C. collinus, an understorey shrub consistently recorded the lowest litter concentrations for all nutrients. The overriding pattern is one of higher nutrient levels in the overstorey leaf litter and lower concentrations in the understorey litter. Furthermore, as decomposition proceeded, the nitrogen concentration of the residual biomass increased.     

Root distribution pattern of the wild jack tree (Artocarpus hirsutus Lamk.) as studied by 32P soil injection method

Root distribution of the wild jack tree (Artocarpus hirsutus) was determined by selective placement of ³²P at various depths and lateral distances from the tree, in Kerala, India. In eight-and-a-half-year-old trees growing on a lateritic site, absorption of ³²P from a lateral distance of 75 cm and 30 cm depth was much greater than from 150 and 225 cm lateral distance and 60 and 90 cm depth. Root activity declined with increasing depth and lateral distance. Most of the physiologically active roots were concentrated within a radius of 75 cm and 30 cm depth, although the tap root might reach even deeper. Possibly, surface accumulation of feeder roots may cause considerable overlap of the tree and crop root zones in intercropping situations. However, as the tree roots seldom extend beyond 2.25 m laterally from the trunk, the effect of overlapping root zones and the associated competitive effects may not be a serious problem for intercropping during the first few years (<10 years after planting) of tree growth.     

Antimicrobial activity of Memecylon malabaricum leaves

The petroleum ether, chloroform and methanol extracts of Memecylon malabaricum leaves were tested for antimicrobial activity. Only methanol extract has shown activity against bacteria both Gram (+) and Gram (-), and fungi.     

Antibacterial activity of Mappia foetida leaves and stem

Successive petroleum ether, chloroform and methanol extracts of Mappia foetida leaves and stem were tested for their antibacterial activity. The methanol fractions were found to be most effective against all the tested organisms.     

Status of floor vegetation under some monoculture and mixculture plantations in North India

A study conducted to assess the floor vegetation shows the presence of 17 species underPopulus deltoides in comparison to 28, 29 and 35 underAlbizia lebbeck, Dalbergia sissoo and mix-culture plantations, respectively. Further, the biomass and density of floor vegetation is considerably reduced underP. deltoides compared to other plantations. In addition, the indices for species richness, evenness, dominance and diversity are also reduced underP. deltoides showing some inhibitory mechanism being operative under these plantations. Based on available literature, allelopathy is speculated to be responsible for this reduction.     

Establishment and growth of coniferous seedlings in an altered forest floor after long-term exclusion of deer

We evaluated differences between the forest floors and the establishment and growth of coniferous seedlings in fenced (13 years) and unfenced plots on Mt Ohdaigahara where the sika deer (Cervus nippon) population density is high. Large coniferous seedlings (height > 0.05 m) were less abundant in the unfenced plot, as a result of deer browsing. Small coniferous seedlings (height < 0.05 m), however, were more abundant in the unfenced plot, where most seedlings of Abies homolepis were found on bare ground and those of Picea jezoensis var. hondoensis were found on buttresses and fallen logs. The large area of bare ground in the unfenced plot was caused by deer browsing. Deer therefore have an indirect effect on the emergence and growth of small coniferous seedlings by modifying the forest floor.     

Establishment of Prosopis cineraria (L.) druce in the hot deserts of India

Prosopis cineraria (L.) Druce, commonly known as Jandi, is a deep rooted, nitrogen fixing, multipurpose tree endemic to the hot deserts of India. These trees are the essential component of the agroforestry land use system in these parts of India. The shade-intolerant tree reproduces poorly in nature and is difficult to propagate vegetatively. Germination up to 86.6% was observed after 15 days in seeds soaked in water at room temperature for 72 h. In another treatment, pouring of boiling water twice (at 0 and 6 h) over seeds and germinating after 12 h produced germination rates of 92.6%. Field establishment of containerized transplants in polythene bags (22×10 cm; 150 gauge) gave 90.3% survival after 6 months and 75.4% survival after 24 months. Seedlings were irrigated once during transplanting with 15 1 water. Bare root transplants and manual direct seeding after 6 months had a survival of 30.8 and 45.0%, respectively. Increased levels of nutrients (N, P and K), moisture content and organic carbon were observed under plantations as compared to open areas.     

New gingerdione from the rhizomes of Zingiber officinale

A new gingerdione has been isolated from the rhizomes of Zingiber officinale and identified as 1-dehydrogingerdione (1).     

Floristic attributes of small cardamom (Elettaria cardamomum (L.) Maton) growing areas in the Western Ghats of peninsular India

A field study was conducted in the Western Ghats of peninsular India to test the following two hypotheses: (1) lower floristic diversity for the cardamom hill reserves (CHR —a traditional agroforestry system of the tropics) compared to undisturbed evergreen forests and (2) a truncated vegetation structure for shade trees in the cardamom areas. The experimental sites involved three CHRs and an evergreen forest site.The CHRs, regardless of their locations, were characterized by lower floristic diversity and density than the evergreen forest site. The undisturbed forest site at Ayyappancoil registered the highest floristic richness and diversity (Simpson's floristic diversity index, D=0.93), followed by the well-managed CHR site, suggesting that managerial interventions may have a strong bearing on the floristic diversity of CHRs. The current suite of species in the CHRs included both heliophilic as well as shade-tolerant components. However, dominant tree species, their density and relative abundance exhibited marked variations among the CHR sites, albeit about one-third of the species were common at all sites.Stand physiognomy was characterized by the dominance of a single layer of trees in the CHRs, while the wet evergreen forest exhibited a multilayered canopy structure. Some of the lower height classes were poorly represented in the cardamom areas, whereas the evergreen forests depicted an inverse J shaped height distribution pattern. Implicit in the truncated stand structure of the CHR is the poor regeneration status, due to systematic removal of the lower size classes.