The Influence of a Change in Farm Dairy Practice on the Bacterial Flora of Fresh and Stored Raw Milk

S ummary . The change in farm dairy practice described resulted in an increase in the percentage of pseudomonads isolated from milks stored at 22, 15 and 5° and in the numbers of Gram-negative rod cultures resistant to hypochlorite.     

Robustness of the Bacterial Community in the Cabbage White Butterfly Larval Midgut

Microbial communities typically vary in composition and structure over space and time. Little is known about the inherent characteristics of communities that govern various drivers of these changes, such as random variation, changes in response to perturbation, or susceptibility to invasion. In this study, we use 16S ribosomal RNA gene sequences to describe variation among bacterial communities in the midguts of cabbage white butterfly (Pieris rapae) larvae and examine the influence of community structure on susceptibility to invasion. We compared communities in larvae experiencing the same conditions at different times (temporal variation) or fed different diets (perturbation). The most highly represented phylum was Proteobacteria, which was present in all midgut communities. The observed species richness ranged from six to 15, and the most abundant members affiliated with the genera Methylobacteria, Asaia, Acinetobacter, Enterobacter, and Pantoea. Individual larvae subjected to the same conditions at the same time harbored communities that were highly similar in structure and membership, whereas the communities observed within larval populations changed with diet and over time. In addition, structural changes due to perturbation coincided with enhanced susceptibility to invasion by Enterobacter sp. NAB3R and Pantoea stewartii CWB600, suggesting that resistance to invasion is in part governed by community structure. These findings along with the observed conservation of membership at the phylum level, variation in structure and membership at lower taxonomic levels, and its relative simplicity make the cabbage white butterfly larval community an attractive model for studying community dynamics and robustness.     

The Development of Aerobic Spoilage Flora on Meat Stored at Chill Temperatures

In meat juice medium, aerobic spoilage bacteria utilized the following substrates in the order shown: Pseudomonos , glucose, amino acids, lactic acid; Acinetobacter , amino acids, lactic acid: Enterobacter , glucose, glucose-6-phosphate, amino acids; Microbacterium thermosphactum , glucose, glutamate. All the bacteria grew at their maximum rate utilizing the first and second substrates, but the growth rates declined when these were exhausted. The growth rate of Acinetobacter was reduced at pH 5·7 and below. All other species grew at their maximum rate within the pH range 5·5–7·0. On meat pseudomonads grew faster than the other species at all temperatures between 2° and 15°C. Interactions between any two species were observed only when one organism had attained its maximum cell density. Substrate exhaustion at the meat surface did not limit bacterial growth and it is suggested that the maximum cell density of aerobic spoilage cultures is determined by oxygen limitation of growth.     

The Bacterial Production of Glutamic Acid in Stored Comminuted Beef

S ummary . In meat stored at 4, 9 and 15°, the free glutamic acid produced from the deamidation of glutamine resulted from bacterial activity, meat glutaminase playing little or no part. The percentage of glutaminase active bacteria increased from 40 in fresh meat to 100 after storage for 65 h at 15°; Pseudomonas-Achromobacter spp. predominated after 41 h at 15°. The glutaminase of a typical pseudomonad was optimally active at 36° and at pH 5 and appeared to be constitutive in nature.     

秦岭药用真菌区系研究

旨在积累秦岭山区药用真菌资源的基础资料,同时,也是该地区野生真菌资源的开发、利用和保护前提。此次研究采用野外踏查、室内查对标本和校对相关文献资料的方法对秦岭山区药用真菌种质资源及其区系特点进行了初步的研究和探讨。结果显示,秦岭共有药用真菌196种,其中隶属于39科90属,含10种以上的科有4科,共107种,占全部种数的54.59%,分别为多孔菌科、红菇科、口蘑科和马勃科;含5种及5以上的属有8属,共5 9种,占总种数的30.09%,依次为红菇属、乳菇属、栓菌属、木层孔菌属、鬼伞属、马勃属、粘盖牛肝菌属、秃马勃属;从属的区系地理成分上可划分为广布成分(67.78%)、泛热带成分(4.44%)、热带亚洲-热带非洲成分(1.59%)和北温带成分(26.67%)4个分布型,其中以广布成分为主,表现典型温带区系特征。从其药理作用上分析,主要有抗癌、抗菌消炎、舒筋活络、止血、调节免疫力、养胃、补益等作用。     

The Development of the Anaerobic Spoilage Flora of Meat Stored at Chill Temperatures

In meat juice medium under anaerobic conditions, spoilage bacteria utilized the following substrates: Microbacterium thermosphactum , glucose; Enterobacter , glucose and glucose-6-phosphate; Lactobacillus , glucose and arginine. On meat stored anaerobically. Lactobacillus grew faster than the other species at all temperatures between 2° and 15 °C. Enterobacter had a greater affinity for glucose than M. thermosphactum. As a result, high numbers of Enterobacter inhibited growth of M. thermosphactum under the glucose limiting conditions at the meat surface. High numbers of Lactobacillus inhibited growth of both competing species, apparently by producing an inhibitory substance.     

The Bacterial Flora of the Rumen of Healthy and Bloating Calves

Rumen samples from five healthy milk-fed calves and one healthy calf given a milk-replacer diet containing yeast protein had pH values of 6.5–8.0, total counts of ca. 10¹⁰/ml and viable counts of 10⁸-10¹⁰/ml. The facultatively and strictly anaerobic, and obligately aerobic, components of the floras were enumerated and identified. Similar tests performed on samples from two calves bloating on the yeast diet had pH values of 4.8 and 5.3, and although total and viable counts were of the same order as those from healthy calves, obligately aerobic bacteria were not detected and counts of lactobacilli were elevated. Infusion of the rumen of a calf with yeast diet caused a reduction in pH from 7.3–5.1 and an increase of at least 100-fold in the numbers of organisms capable of forming copious gas from yeast diet. Results suggest that milk or milk-replacer diet normally does not enter the rumen to any extent but when it does, due perhaps to poor palatability, bloat may ensue.     

Mites as Selective Fungal Carriers in Stored Grain Habitats

Mites are well documented as vectors of micromycetes in stored products. Since their vectoring capacity is low due to their small size, they can be serious vectors only where there is selective transfer of a high load of specific fungal species. Therefore the aim of our work was to find out whether the transfer of fungi is selective. Four kinds of stored seeds (wheat, poppy, lettuce, mustard) infested by storage mites were subjected to mycological analysis. We compared the spectrum of micromycete species isolated from different species of mites (Acarus siro, Lepidoglyphus destructor, Tyrophagus putrescentiae, Caloglyphus rhizoglyphoides and Cheyletus malaccensis) and various kinds of stored seeds. Fungi were separately isolated from (a) the surface of mites, (b) the mites' digestive tract (= faeces), and (c) stored seeds and were then cultivated and determined. The fungal transport via mites is selective. This conclusion is supported by (i) lower numbers of isolated fungal species from mites than from seeds; (ii) lower Shannon–Weaver diversity index in the fungal communities isolated from mites than from seeds; (iii) significant effect of mites/seeds as environmental variables on fungal presence in a redundancy analysis (RDA); (iv) differences in composition of isolated fungi between mite species shown by RDA. The results of our work support the hypothesis that mite–fungal interactions are dependent on mite species. The fungi attractive to mites seem to be dispersed more than others. The selectivity of fungal transport via mites enhances their pest importance.     

The Bacterial Flora of the Gut Contents and Environment of Larval Lampreys

Rogers, P. A., Glenn, A. R., Potter, I. C. 1980. The bacterial flora of the gut contents and environment of larval lampreys. (School of Environmental and Life Sciences, Murdoch University, Australia.) — Acta zool. (Stockh.) 61(1): 23–27. The microbial flora of the contents of the intestine of larval lampreys, as well as of the water and substrate in the ammocoetes' habitat, have been cultured on Trypticase Soy Agar. The bacteria have been separated into taxonomic groups, using the scheme of Cowan and Steele (1974) and the API 20E system. The microbial flora of the gut contents of larval lampreys closely parallels that found in the environment in which the ammocoetes live. Bacillus, Aeromonas and Aeromonas-like organisms were by far the most abundant bacteria identified, followed by Pseudomonas and members of the Enterobacteriaceae. The only anaerobic components of the bacterial flora in the gut contents and the environment were Clostridium and a relatively uncommon and unidentified Gram-negative organism. Estimates of abundance of the microflora indicated that the concentration of bacteria was much greater in both the gut contents and the substrate than in the water overlying the animals' burrow.     

Fungal and Bacterial Activity in Northern Peatlands

Selective inhibition of substrate-induced respiration with antibiotics cycloheximide and streptomycin sulphate provided insight into eukaryotic versus prokaryotic activities in surface peat soil of three Canadian peatlands. Prokaryotic and eukaryotic communities in peatlands are important in the net sequestration of atmospheric carbon dioxide and therefore play a unique role in global carbon cycling. Selective inhibition techniques were generally successful, with a maximum non-target inhibition of only 17%. Assuming that eukaryotic and prokaryotic activities were dominated by fungi and bacteria respectively, across 3 ecologically and hydrologically diverse and spatially dispersed peatlands, we demonstrated bacterial dominance in a bog and a poor fen both with acidic and primarily Sphagnum derived peat soil and in a near pH neutral wetter rich fen with sedge peat (fungal to bacterial activity ratio = 0.31 to 0.68). These results differ in that in other acidic environments, such as conifer forest soils, fungal to bacterial activity ratios are mostly greater than 1 indicative of fungal dominance.     

The Effect of Antibiotics on Associated Bacterial Community of Stored Product Mites

Background

Bacteria are associated with the gut, fat bodies and reproductive organs of stored product mites (Acari: Astigmata). The mites are pests due to the production of allergens. Addition of antibiotics to diets can help to characterize the association between mites and bacteria.

Methodology and Principal Findings

Ampicillin, neomycin and streptomycin were added to the diets of mites and the effects on mite population growth (Acarus siro, Lepidoglyphus destructor and Tyrophagus putrescentiae) and associated bacterial community structure were assessed. Mites were treated by antibiotic supplementation (1 mgg⁻¹ of diet) for 21 days and numbers of mites and bacterial communities were analyzed and compared to the untreated control. Bacterial quantities, determined by real-time PCR, significantly decreased in antibiotic treated specimens from 5 to 30 times in A. siro and T. putrescentiae, while no decline was observed in L. destructor. Streptomycin treatment eliminated Bartonella-like bacteria in the both A. siro and T. putrescentiae and Cardinium in T. putrescentiae. Solitalea-like bacteria proportion increased in the communities of neomycin and streptomycin treated A. siro specimens. Kocuria proportion increased in the bacterial communities of ampicillin and streptomycin treated A. siro and neomycin and streptomycin treated L. destructor.

Conclusions/Significance

The work demonstrated the changes of mite associated bacterial community under antibiotic pressure in pests of medical importance. Pre-treatment of mites by 1 mgg⁻¹ antibiotic diets improved mite fitness as indicated accelerated population growth of A. siro pretreated streptomycin and neomycin and L. destructor pretreated by neomycin. All tested antibiotics supplemented to diets caused the decrease of mite growth rate in comparison to the control diet.     

The Aerobic Flora of Stored Meat with Particular Reference to the Use of Selective Media

The changes in the aerobic flora of meats stored at 15, 9 and 4° have been compared by means of selective media and by screening representative isolates. By both methods the predominant spoilage flora at the three temperatures belonged to the genus Pseudomonas . Using the medium of Masurvosky, Goldblith & Voss (1963) preliminary investigations have been made into the numbers of pseudomonads in meats.     

The Bacterial Flora of some Queensland Fish and its Ability to cause Spoilage

The bacterial flora were determined qualitatively and quantitatively on samples taken at various stages of handling several species of fish of commercial importance in Queensland. There was an overall increase in the number of bacteria during handling and processing; both the composition and quantity of the bacterial flora of individual samples taken at each stage of handling varied widely. Members of the genus Micrococcus formed the major proportion of the flora of freshly caught fish. Pseudomonas and Moraxella spp. were predominant amongst the bacterial flora able to grow at 2° and constituted the bulk of the population in samples with high bacterial counts. This psychrophilic population was markedly reduced at the filleting stage. A medium prepared by the action of trypsin on a fish muscle homogenate was used to test bacterial isolates for their ability to produce odours. Forty-three per cent of the pseudomonad isolates produced sulphydryl odours at 5°. Only small proportions of the other groups produced detectable odours. Members of the genus Pseudomonas were considered the most important fish spoilage bacteria under the conditions found in Queensland.     

长白山森林土壤真菌区系研究

本研究对长白山自然保护区不同海拔、林型、土壤剖面的森林土壤真菌进行分离鉴定,从而为建立森林真菌资源库提供种质资源,并为森林生物资源管理提供科学依据。在该地区6个不同林型中,采用“之”形路线及土壤剖面取样法多点采集土壤样品,按照标准方法初步分离鉴定出真菌28个属,其中包括1个中国新纪录属,即球壳属(Sphaerodes)。研究结果表明,土壤真菌区系与森林(植被)类型、土壤剖面层次密切相关:美人松落叶松林、红松阔叶林和红松云冷杉林土壤真菌的种类明显多于鱼鳞云冷杉林、岳桦林和高山苔原带;土壤不同剖面层次上的真菌种群数量高低依次为落叶层>腐殖质层>土壤层;同一林型下不同土壤层面上优势菌属的组成也具有一定的差异,且不同层面上也存在着其特有的优势菌属。